User Guide

• 1: Pepr CLI
• 2: Pepr SDK
• 3: Pepr Modules
• 4: Actions
• 4.1: Mutate
• 4.2: Validate
• 4.3: Reconcile
• 4.4: Watch
• 4.5: Finalize
• 4.6: Using Alias Child Logger in Actions
• 5: Pepr Capabilities
• 6: Pepr Store
• 7: Custom Resources
• 8: OnSchedule
• 9: RBAC Modes
• 10: Metrics Endpoints
• 11: WASM Support
• 12: Customization
• 13: Pepr Filters

1 - Pepr CLI

npx pepr init

Initialize a new Pepr Module.

Options:

• --skip-post-init - Skip npm install, git init and VSCode launch.
• --confirm - Skip verification prompt when creating a new module.
• --description <string> - Explain the purpose of the new module.
• --name <string> - Set the name of the new module.
• --skip-post-init - Skip npm install, git init, and VSCode launch.
• --errorBehavior <audit|ignore|reject> - Set an errorBehavior.

npx pepr update

Update the current Pepr Module to the latest SDK version. This command is not recommended for production use, instead, we recommend Renovate or Dependabot for automated updates.

Options:

• --skip-template-update - Skip updating the template files

npx pepr dev

Connect a local cluster to a local version of the Pepr Controller to do real-time debugging of your module. Note the npx pepr dev assumes a K3d cluster is running by default. If you are working with Kind or another docker-based K8s distro, you will need to pass the --host host.docker.internal option to npx pepr dev. If working with a remote cluster you will have to give Pepr a host path to your machine that is reachable from the K8s cluster.

NOTE: This command, by necessity, installs resources into the cluster you run it against. Generally, these resources are removed once the pepr dev session ends but there are two notable exceptions:

• the pepr-system namespace, and
• the PeprStore CRD.

These can’t be auto-removed because they’re global in scope & doing so would risk wrecking any other Pepr deployments that are already running in-cluster. If (for some strange reason) you’re not pepr dev-ing against an ephemeral dev cluster and need to keep the cluster clean, you’ll have to remove these hold-overs yourself (or not)!

Options:

• -h, --host [host] - Host to listen on (default: “host.k3d.internal”)
• --confirm - Skip confirmation prompt

npx pepr deploy

Deploy the current module into a Kubernetes cluster, useful for CI systems. Not recommended for production use.

Options:

• -i, --image [image] - Override the image tag
• --confirm - Skip confirmation prompt
• --pullSecret <name> - Deploy imagePullSecret for Controller private registry
• --docker-server <server> - Docker server address
• --docker-username <username> - Docker registry username
• --docker-email <email> - Email for Docker registry
• --docker-password <password> - Password for Docker registry
• --force - Force deploy the module, override manager field

npx pepr monitor

Monitor Validations for a given Pepr Module or all Pepr Modules.

Usage:

npx pepr monitor [options] [module-uuid]

Options:

• -h, --help - Display help for command

npx pepr uuid

Module UUID(s) currently deployed in the cluster with their descriptions.

Options:

• [uuid] - Specific module UUID

npx pepr build

Create a zarf.yaml and K8s manifest for the current module. This includes everything needed to deploy Pepr and the current module into production environments.

Options:

• -e, --entry-point [file] - Specify the entry point file to build with. (default: “pepr.ts”)
• -n, --no-embed - Disables embedding of deployment files into output module. Useful when creating library modules intended solely for reuse/distribution via NPM
• -r, --registry-info [<registry>/<username>] - Registry Info: Image registry and username. Note: You must be signed into the registry
• -o, --output-dir [output directory] - Define where to place build output
• --timeout [timeout] - How long the API server should wait for a webhook to respond before treating the call as a failure
• --rbac-mode [admin|scoped] - Rbac Mode: admin, scoped (default: admin) (choices: “admin”, “scoped”, default: “admin”)
• -i, --custom-image [custom-image] - Custom Image: Use custom image for Admission and Watcher Deployments.
• --registry [GitHub, Iron Bank] - Container registry: Choose container registry for deployment manifests.
• -v, --version <version>. Example: '0.27.3' - The version of the Pepr image to use in the deployment manifests.
• --withPullSecret <imagePullSecret> - Image Pull Secret: Use image pull secret for controller Deployment.
• -z, --zarf [manifest|chart] - The Zarf package type to generate: manifest or chart (default: manifest).

npx pepr kfc

Execute a kubernetes-fluent-client command. This command is a wrapper around kubernetes-fluent-client.

Usage:

npx pepr kfc [options] [command]

If you are unsure of what commands are available, you can run npx pepr kfc to see the available commands.

For example, to generate usable types from a Kubernetes CRD, you can run npx pepr kfc crd [source] [directory]. This will generate the types for the [source] CRD and output the generated types to the [directory].

You can learn more about the kubernetes-fluent-client here.

2 - Pepr SDK

To use, import the sdk from the pepr package:

import { sdk } from "pepr";

containers

Returns list of all containers in a pod. Accepts the following parameters:

• @param peprValidationRequest The request/pod to get the containers from
• @param containerType The type of container to get

Usage:

Get all containers

const { containers } = sdk;
let result = containers(peprValidationRequest)

Get only the standard containers

const { containers } = sdk;
let result = containers(peprValidationRequest, "containers")

Get only the init containers

const { containers } = sdk;
let result = containers(peprValidationRequest, "initContainers")

Get only the ephemeral containers

const { containers } = sdk;
let result = containers(peprValidationRequest, "ephemeralContainers")

getOwnerRefFrom

Returns the owner reference for a Kubernetes resource as an array. Accepts the following parameters:

• @param kubernetesResource: GenericKind The Kubernetes resource to get the owner reference for
• @param blockOwnerDeletion: boolean If true, AND if the owner has the “foregroundDeletion” finalizer, then the owner cannot be deleted from the key-value store until this reference is removed.
• @param controller: boolean If true, this reference points to the managing controller.

Usage:

const { getOwnerRefFrom } = sdk;
const ownerRef = getOwnerRefFrom(kubernetesResource);

writeEvent

Write a K8s event for a CRD. Accepts the following parameters:

• @param kubernetesResource: GenericKind The Kubernetes resource to write the event for
• @param event The event to write, should contain a human-readable message for the event
• @param eventType The type of event to write, for example “Warning”
• @param eventReason The reason for the event, for example “ReconciliationFailed”
• @param reportingComponent The component that is reporting the event, for example “uds.dev/operator”
• @param reportingInstance The instance of the component that is reporting the event, for example process.env.HOSTNAME

Usage:

const { writeEvent } = sdk;
writeEvent(
  kubernetesResource,
  event,
  "Warning",
  "ReconciliationFailed",
  "uds.dev/operator",
  process.env.HOSTNAME,
);

sanitizeResourceName

Returns a sanitized resource name to make the given name a valid Kubernetes resource name. Accepts the following parameter:

• @param resourceName The name of the resource to sanitize

Usage:

const { sanitizeResourceName } = sdk;
const sanitizedResourceName = sanitizeResourceName(resourceName)

See Also

Looking for information on the Pepr mutate helpers? See Mutate Helpers for information on those.

3 - Pepr Modules

What is a Pepr Module?

A Pepr Module is a collection of files that can be used to create a new Pepr Project. A Pepr Module can be used to create a new Pepr Project by using the npx pepr init command.

4 - Actions

Overview

An action is a discrete set of behaviors defined in a single function that acts on a given Kubernetes GroupVersionKind (GVK) passed in during the admission controller lifecycle. Actions are the atomic operations that are performed on Kubernetes resources by Pepr.

For example, an action could be responsible for adding a specific label to a Kubernetes resource, or for modifying a specific field in a resource’s metadata. Actions can be grouped together within a Capability to provide a more comprehensive set of operations that can be performed on Kubernetes resources.

Actions are Mutate(), Validate(), Watch(), Reconcile(), and Finalize(). Both Mutate and Validate actions run during the admission controller lifecycle, while Watch and Reconcile actions run in a separate controller that tracks changes to resources, including existing resource; the Finalize action spans both the admission & afterward.

Let’s look at some example actions that are included in the HelloPepr capability that is created for you when you npx pepr init:

In this first example, Pepr is adding a label and annotation to a ConfigMap with the name example-1 when it is created. Comments are added to each line to explain in more detail what is happening.

// When(a.<Kind>) filters which GroupVersionKind (GVK) this action should act on.
When(a.ConfigMap)
  // This limits the action to only act on new resources.
  .IsCreated()
  // This limits the action to only act on resources with the name "example-1".
  .WithName("example-1")
  // Mutate() is where we define the actual behavior of this action.
  .Mutate(request => {
    // The request object is a wrapper around the K8s resource that Pepr is acting on.
    request
      // Here we are adding a label to the ConfigMap.
      .SetLabel("pepr", "was-here")
      // And here we are adding an annotation.
      .SetAnnotation("pepr.dev", "annotations-work-too");

    // Note that we are not returning anything here. This is because Pepr is tracking the changes in each action automatically.
  });

In this example, a Validate action rejects any ConfigMap in the pepr-demo namespace that has no data.

When(a.ConfigMap)
  .IsCreated()
  .InNamespace("pepr-demo")
  // Validate() is where we define the actual behavior of this action.
  .Validate(request => {
    // If data exists, approve the request.
    if (request.Raw.data) {
      return request.Approve();
    }

    // Otherwise, reject the request with a message and optional code.
    return request.Deny("ConfigMap must have data");
  });

In this example, a Watch action on the name and phase of any ConfigMap.Watch actions run in a separate controller that tracks changes to resources, including existing resources so that you can react to changes in real-time. It is important to note that Watch actions are not run during the admission controller lifecycle, so they cannot be used to modify or validate resources. They also may run multiple times for the same resource, so it is important to make sure that your Watch actions are idempotent. In a future release, Pepr will provide a better way to control when a Watch action is run to avoid this issue.

When(a.ConfigMap)
  // Watch() is where we define the actual behavior of this action.
  .Watch((cm, phase) => {
    Log.info(cm, `ConfigMap ${cm.metadata.name} was ${phase}`);
  });

There are many more examples in the HelloPepr capability that you can use as a reference when creating your own actions. Note that each time you run npx pepr update, Pepr will automatically update the HelloPepr capability with the latest examples and best practices for you to reference and test directly in your Pepr Module.

In some scenarios involving Kubernetes Resource Controllers or Operator patterns, opting for a Reconcile action could be more fitting. Comparable to the Watch functionality, Reconcile is responsible for monitoring the name and phase of any Kubernetes Object. It operates within the Watch controller dedicated to observing modifications to resources, including those already existing, enabling responses to alterations as they occur. Unlike Watch, however, Reconcile employs a Queue to sequentially handle events once they are returned by the Kubernetes API. This allows the operator to handle bursts of events without overwhelming the system or the Kubernetes API. It provides a mechanism to back off when the system is under heavy load, enhancing overall stability and maintaining the state consistency of Kubernetes resources, as the order of operations can impact the final state of a resource.

When(WebApp)
  .IsCreatedOrUpdated()
  .Validate(validator)
  .Reconcile(async instance => {

    const { namespace, name, generation } = instance.metadata;

    if (!instance.metadata?.namespace) {
      Log.error(instance, `Invalid WebApp definition`);
      return;
    }

    const isPending = instance.status?.phase === Phase.Pending;
    const isCurrentGeneration = generation === instance.status?.observedGeneration;

    if (isPending || isCurrentGeneration) {
      Log.debug(instance, `Skipping pending or completed instance`);
      return;
    }

    Log.debug(instance, `Processing instance ${namespace}/${name}`);


    try {
      // Set Status to pending
      await updateStatus(instance, { phase: Phase.Pending });

      // Deploy Deployment, ConfigMap, Service, ServiceAccount, and RBAC based on instance
      await Deploy(instance);

      // Set Status to ready
      await updateStatus(instance, {
        phase: Phase.Ready,
        observedGeneration: instance.metadata.generation,
      });
    } catch (e) {
      Log.error(e, `Error configuring for ${namespace}/${name}`);

      // Set Status to failed
      void updateStatus(instance, {
        phase: Phase.Failed,
        observedGeneration: instance.metadata.generation,
      });
    }
  });

4.1 - Mutate

Mutating admission webhooks are invoked first and can modify objects sent to the API server to enforce custom defaults. After an object is sent to Pepr’s Mutating Admission Webhook, Pepr will annotate the object to indicate the status.

After a successful mutation of an object in a module with UUID static-test, and capability name hello-pepr, expect to see this annotation: static-test.pepr.dev/hello-pepr: succeeded.

Helpers

SetLabel

SetLabel is used to set a lable on a Kubernetes object as part of a Pepr Mutate action.

For example, to add a label when a ConfigMap is created:

When(a.ConfigMap)
  .IsCreated()
  .Mutate(request => {
    request
      // Here we are adding a label to the ConfigMap.
      .SetLabel("pepr", "was-here")

    // Note that we are not returning anything here. This is because Pepr is tracking the changes in each action automatically.
  });

RemoveLabel

RemoveLabel is used to remove a label on a Kubernetes object as part of a Pepr Mutate action.

For example, to remove a label when a ConfigMap is updated:

When(a.ConfigMap)
  .IsCreated()
  .Mutate(request => {
    request
      // Here we are removing a label from the ConfigMap.
      .RemoveLabel("remove-me")

    // Note that we are not returning anything here. This is because Pepr is tracking the changes in each action automatically.
  });

SetAnnotation

SetAnnotation is used to set an annotation on a Kubernetes object as part of a Pepr Mutate action.

For example, to add an annotation when a ConfigMap is created:

When(a.ConfigMap)
  .IsCreated()
  .Mutate(request => {
    request
      // Here we are adding an annotation to the ConfigMap.
      .SetAnnotation("pepr.dev", "annotations-work-too");

    // Note that we are not returning anything here. This is because Pepr is tracking the changes in each action automatically.
  });

RemoveAnnotation

RemoveAnnotation is used to remove an annotation on a Kubernetes object as part of a Pepr Mutate action.

For example, to remove an annotation when a ConfigMap is updated:

When(a.ConfigMap)
  .IsUpdated()
  .Mutate(request => {
    request
      // Here we are removing an annotation from the ConfigMap.
      .RemoveAnnotation("remove-me");

    // Note that we are not returning anything here. This is because Pepr is tracking the changes in each action automatically.
  });

See Also

Looking for some more generic helpers? Check out the Module Author SDK for information on other things that Pepr can help with.

4.2 - Validate

After the Mutation phase comes the Validation phase where the validating admission webhooks are invoked and can reject requests to enforce custom policies.

Validate does not annotate the objects that are allowed into the cluster, but the validation webhook can be audited with npx pepr monitor. Read the monitoring docs for more information.

4.3 - Reconcile

Reconcile functions the same as Watch but is tailored for building Kubernetes Controllers and Operators because it processes callback operations in a Queue, guaranteeing ordered and synchronous processing of events, even when the system may be under heavy load.

Ordering can be configured to operate in one of two ways: as a single queue that maintains ordering of operations across all resources of a kind (default) or with separate processing queues per resource instance.

See Configuring Reconcile for more on configuring how Reconcile behaves.

4.4 - Watch

Kubernetes supports efficient change notifications on resources via watches. Pepr uses the Watch action for monitoring resources that previously existed in the cluster and for performing long-running asynchronous events upon receiving change notifications on resources, as watches are not limited by timeouts.

4.5 - Finalize

A specialized combination of Pepr’s Mutate & Watch functionalities that allow a module author to run logic while Kubernetes is Finalizing a resource (i.e. cleaning up related resources after a deleteion request has been accepted).

This method will:

1. Inject a finalizer into the metadata.finalizers field of the requested resource during the mutation phase of the admission.

2. Watch appropriate resource lifecycle events & invoke the given callback.

3. Remove the injected finalizer from the metadata.finalizers field of the requested resource.

4.6 - Using Alias Child Logger in Actions

You can use the Alias function to include a user-defined alias in the logs for Mutate, Validate, and Watch actions. This can make for easier debugging since your user-defined alias will be included in the action’s logs. This is especially useful when you have multiple actions of the same type in a single module.

The below example uses Mutate, Validate, and Watch actions with the Alias function:

When(a.Pod)
  .IsCreatedOrUpdated()
  .Alias("mutate")
  .Mutate((po, logger) => {
    logger.info(`alias: mutate ${po.Raw.metadata.name}`);
  });
When(a.Pod)
  .IsCreatedOrUpdated()
  .Alias("validate")
  .Validate((po, logger) => {
    logger.info(`alias: validate ${po.Raw.metadata.name}`);
    return po.Approve();
  });
When(a.Pod)
  .IsCreatedOrUpdated()
  .Alias("watch")
  .Watch((po, _, logger) => {
    logger.info(`alias: watch ${po.metadata.name}`);
  });
When(a.Pod)
  .IsCreatedOrUpdated()
  .Alias("reconcile")
  .Reconcile((po, _, logger) => {
    logger.info(`alias: reconcile ${po.metadata.name}`);
  });

This will result in log entries when creating a Pod with the that include the alias:

Logs for Mutate When Pod red is Created:

{"level":30,"time":1726632368808,"pid":16,"hostname":"pepr-static-test-6786948977-6hbnt","uid":"b2221631-e87c-41a2-94c8-cdaef15e7b5f","namespace":"pepr-demo","name":"/red","gvk":{"group":"","version":"v1","kind":"Pod"},"operation":"CREATE","admissionKind":"Mutate","msg":"Incoming request"}
{"level":30,"time":1726632368808,"pid":16,"hostname":"pepr-static-test-6786948977-6hbnt","uid":"b2221631-e87c-41a2-94c8-cdaef15e7b5f","namespace":"pepr-demo","name":"/red","msg":"Processing request"}
{"level":30,"time":1726632368808,"pid":16,"hostname":"pepr-static-test-6786948977-6hbnt","msg":"Executing mutation action with alias: mutate"}
{"level":30,"time":1726632368808,"pid":16,"hostname":"pepr-static-test-6786948977-6hbnt","alias":"mutate","msg":"alias: mutate red"}
{"level":30,"time":1726632368808,"pid":16,"hostname":"pepr-static-test-6786948977-6hbnt","uid":"b2221631-e87c-41a2-94c8-cdaef15e7b5f","namespace":"pepr-demo","name":"hello-pepr","msg":"Mutation action succeeded (mutateCallback)"}
{"level":30,"time":1726632368808,"pid":16,"hostname":"pepr-static-test-6786948977-6hbnt","uid":"b2221631-e87c-41a2-94c8-cdaef15e7b5f","namespace":"pepr-demo","name":"/red","res":{"uid":"b2221631-e87c-41a2-94c8-cdaef15e7b5f","allowed":true,"patchType":"JSONPatch","patch":"W3sib3AiOiJhZGQiLCJwYXRoIjoiL21ldGFkYXRhL2Fubm90YXRpb25zL3N0YXRpYy10ZXN0LnBlcHIuZGV2fjFoZWxsby1wZXByIiwidmFsdWUiOiJzdWNjZWVkZWQifV0="},"msg":"Check response"}
{"level":30,"time":1726632368809,"pid":16,"hostname":"pepr-static-test-6786948977-6hbnt","uid":"b2221631-e87c-41a2-94c8-cdaef15e7b5f","method":"POST","url":"/mutate/c1a7fb6e3f2ab9dc08909d2de4166987520f317d53b759ab882dfd0b1c198479?timeout=10s","status":200,"duration":"1 ms"}

Logs for Validate When Pod red is Created:

{"level":30,"time":1726631437605,"pid":16,"hostname":"pepr-static-test-6786948977-j7f9h","uid":"731eff93-d457-4ffc-a98c-0bcbe4c1727a","namespace":"pepr-demo","name":"/red","gvk":{"group":"","version":"v1","kind":"Pod"},"operation":"CREATE","admissionKind":"Validate","msg":"Incoming request"}
{"level":30,"time":1726631437606,"pid":16,"hostname":"pepr-static-test-6786948977-j7f9h","uid":"731eff93-d457-4ffc-a98c-0bcbe4c1727a","namespace":"pepr-demo","name":"/red","msg":"Processing validation request"}
{"level":30,"time":1726631437606,"pid":16,"hostname":"pepr-static-test-6786948977-j7f9h","uid":"731eff93-d457-4ffc-a98c-0bcbe4c1727a","namespace":"pepr-demo","name":"hello-pepr","msg":"Processing validation action (validateCallback)"}
{"level":30,"time":1726631437606,"pid":16,"hostname":"pepr-static-test-6786948977-j7f9h","msg":"Executing validate action with alias: validate"}
{"level":30,"time":1726631437606,"pid":16,"hostname":"pepr-static-test-6786948977-j7f9h","alias":"validate","msg":"alias: validate red"}
{"level":30,"time":1726631437606,"pid":16,"hostname":"pepr-static-test-6786948977-j7f9h","uid":"731eff93-d457-4ffc-a98c-0bcbe4c1727a","namespace":"pepr-demo","name":"hello-pepr","msg":"Validation action complete (validateCallback): allowed"}
{"level":30,"time":1726631437606,"pid":16,"hostname":"pepr-static-test-6786948977-j7f9h","uid":"731eff93-d457-4ffc-a98c-0bcbe4c1727a","namespace":"pepr-demo","name":"/red","res":{"uid":"731eff93-d457-4ffc-a98c-0bcbe4c1727a","allowed":true},"msg":"Check response"}
{"level":30,"time":1726631437606,"pid":16,"hostname":"pepr-static-test-6786948977-j7f9h","uid":"731eff93-d457-4ffc-a98c-0bcbe4c1727a","method":"POST","url":"/validate/c1a7fb6e3f2ab9dc08909d2de4166987520f317d53b759ab882dfd0b1c198479?timeout=10s","status":200,"duration":"5 ms"}

Logs for Watch and Reconcile When Pod red is Created:

{"level":30,"time":1726798504518,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","msg":"Executing reconcile action with alias: reconcile"}
{"level":30,"time":1726798504518,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","alias":"reconcile","msg":"alias: reconcile red"}
{"level":30,"time":1726798504518,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","msg":"Executing watch action with alias: watch"}
{"level":30,"time":1726798504518,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","alias":"watch","msg":"alias: watch red"}
{"level":30,"time":1726798504521,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","msg":"Executing reconcile action with alias: reconcile"}
{"level":30,"time":1726798504521,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","alias":"reconcile","msg":"alias: reconcile red"}
{"level":30,"time":1726798504521,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","msg":"Executing watch action with alias: watch"}
{"level":30,"time":1726798504521,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","alias":"watch","msg":"alias: watch red"}
{"level":30,"time":1726798504528,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","msg":"Executing reconcile action with alias: reconcile"}
{"level":30,"time":1726798504528,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","alias":"reconcile","msg":"alias: reconcile red"}
{"level":30,"time":1726798504528,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","msg":"Executing watch action with alias: watch"}
{"level":30,"time":1726798504528,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","alias":"watch","msg":"alias: watch red"}
{"level":30,"time":1726798510464,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","msg":"Executing watch action with alias: watch"}
{"level":30,"time":1726798510464,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","alias":"watch","msg":"alias: watch red"}
{"level":30,"time":1726798510466,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","msg":"Executing reconcile action with alias: reconcile"}
{"level":30,"time":1726798510466,"pid":16,"hostname":"pepr-static-test-watcher-6dc69654c9-5ql6b","alias":"reconcile","msg":"alias: reconcile red"}

Note: The Alias function is optional and can be used to provide additional context in the logs. You must pass the logger object as shown above to the action to use the Alias function.

See Also

Looking for some more generic helpers? Check out the Module Author SDK for information on other things that Pepr can help with.

5 - Pepr Capabilities

A capability is set of related actions that work together to achieve a specific transformation or operation on Kubernetes resources. Capabilities are user-defined and can include one or more actions. They are defined within a Pepr module and can be used in both MutatingWebhookConfigurations and ValidatingWebhookConfigurations. A Capability can have a specific scope, such as mutating or validating, and can be reused in multiple Pepr modules.

When you npx pepr init, a capabilities directory is created for you. This directory is where you will define your capabilities. You can create as many capabilities as you need, and each capability can contain one or more actions. Pepr also automatically creates a HelloPepr capability with a number of example actions to help you get started.

Creating a Capability

Defining a new capability can be done via a VSCode Snippet generated during npx pepr init.

1. Create a new file in the capabilities directory with the name of your capability. For example, capabilities/my-capability.ts.

2. Open the new file in VSCode and type create in the file. A suggestion should prompt you to generate the content from there.

[)

If you prefer not to use VSCode, you can also modify or copy the HelloPepr capability to meet your needs instead.

Reusable Capabilities

Pepr has an NPM org managed by Defense Unicorns, @pepr, where capabilities are published for reuse in other Pepr Modules. You can find a list of published capabilities here.

You also can publish your own Pepr capabilities to NPM and import them. A couple of things you’ll want to be aware of when publishing your own capabilities:

• Reuseable capability versions should use the format 0.x.x or 0.12.x as examples to determine compatibility with other reusable capabilities. Before 1.x.x, we recommend binding to 0.x.x if you can for maximum compatibility.

• pepr.ts will still be used for local development, but you’ll also need to publish an index.ts that exports your capabilities. When you build & publish the capability to NPM, you can use npx pepr build -e index.ts to generate the code needed for reuse by other Pepr modules.

• See Pepr Istio for an example of a reusable capability.

6 - Pepr Store

A Lightweight Key-Value Store for Pepr Modules

The nature of admission controllers and general watch operations (the Mutate, Validate and Watch actions in Pepr) make some types of complex and long-running operations difficult. There are also times when you need to share data between different actions. While you could manually create your own K8s resources and manage their cleanup, this can be very hard to track and keep performant at scale.

The Pepr Store solves this by exposing a simple, Web Storage API-compatible mechanism for use within capabilities. Additionally, as Pepr runs multiple replicas of the admission controller along with a watch controller, the Pepr Store provides a unique way to share data between these different instances automatically.

Each Pepr Capability has a Store instance that can be used to get, set and delete data as well as subscribe to any changes to the Store. Behind the scenes, all capability store instances in a single Pepr Module are stored within a single CRD in the cluster. This CRD is automatically created when the Pepr Module is deployed. Care is taken to make the read and write operations as efficient as possible by using K8s watches, batch processing and patch operations for writes.

Key Features

• Asynchronous Key-Value Store: Provides an asynchronous interface for storing small amounts of data, making it ideal for sharing information between various actions and capabilities.
• Web Storage API Compatibility: The store’s API is aligned with the standard Web Storage API, simplifying the learning curve.
• Real-time Updates: The .subscribe() and onReady() methods enable real-time updates, allowing you to react to changes in the data store instantaneously.
• Automatic CRD Management: Each Pepr Module has its data stored within a single Custom Resource Definition (CRD) that is automatically created upon deployment.
• Efficient Operations: Pepr Store uses Kubernetes watches, batch processing, and patch operations to make read and write operations as efficient as possible.

Quick Start

// Example usage for Pepr Store
Store.setItem("example-1", "was-here");
Store.setItem("example-1-data", JSON.stringify(request.Raw.data));
Store.onReady(data => {
  Log.info(data, "Pepr Store Ready");
});
const unsubscribe = Store.subscribe(data => {
  Log.info(data, "Pepr Store Updated");
  unsubscribe();
});

API Reference

Methods

• getItem(key: string): Retrieves a value by its key. Returns null if the key doesn’t exist.
• setItem(key: string, value: string): Sets a value for a given key. Creates a new key-value pair if the key doesn’t exist.
• setItemAndWait(key: string, value: string): Sets a value for a given key. Creates a new key-value pair if the key doesn’t exist. Resolves a promise when the new key and value show up in the store. Note - Async operations in Mutate and Validate are susceptible to timeouts.
• removeItem(key: string): Deletes a key-value pair by its key.
• removeItemAndWait(key: string): Deletes a key-value pair by its key and resolves a promise when the key and value do not show up in the store. Note - Async operations in Mutate and Validate are susceptible to timeouts.
• clear(): Clears all key-value pairs from the store.
• subscribe(listener: DataReceiver): Subscribes to store updates.
• onReady(callback: DataReceiver): Executes a callback when the store is ready.

7 - Custom Resources

Importing Custom Resources

The Kubernetes Fluent Client supports the creation of TypeScript typings directly from Kubernetes Custom Resource Definitions (CRDs). The files it generates can be directly incorporated into Pepr capabilities and provide a way to work with strongly-typed CRDs.

For example (below), Istio CRDs can be imported and used as though they were intrinsic Kubernetes resources.

Generating TypeScript Types from CRDs

Using the kubernetes-fluent-client to produce a new type looks like this:

npx kubernetes-fluent-client crd [source] [directory]

The crd command expects a [source], which can be a URL or local file containing the CustomResourceDefinition(s), and a [directory] where the generated code will live.

The following example creates types for the Istio CRDs:

user@workstation$  npx kubernetes-fluent-client crd https://raw.githubusercontent.com/istio/istio/master/manifests/charts/base/crds/crd-all.gen.yaml crds

Attempting to load https://raw.githubusercontent.com/istio/istio/master/manifests/charts/base/crds/crd-all.gen.yaml as a URL

- Generating extensions.istio.io/v1alpha1 types for WasmPlugin
- Generating networking.istio.io/v1alpha3 types for DestinationRule
- Generating networking.istio.io/v1beta1 types for DestinationRule
- Generating networking.istio.io/v1alpha3 types for EnvoyFilter
- Generating networking.istio.io/v1alpha3 types for Gateway
- Generating networking.istio.io/v1beta1 types for Gateway
- Generating networking.istio.io/v1beta1 types for ProxyConfig
- Generating networking.istio.io/v1alpha3 types for ServiceEntry
- Generating networking.istio.io/v1beta1 types for ServiceEntry
- Generating networking.istio.io/v1alpha3 types for Sidecar
- Generating networking.istio.io/v1beta1 types for Sidecar
- Generating networking.istio.io/v1alpha3 types for VirtualService
- Generating networking.istio.io/v1beta1 types for VirtualService
- Generating networking.istio.io/v1alpha3 types for WorkloadEntry
- Generating networking.istio.io/v1beta1 types for WorkloadEntry
- Generating networking.istio.io/v1alpha3 types for WorkloadGroup
- Generating networking.istio.io/v1beta1 types for WorkloadGroup
- Generating security.istio.io/v1 types for AuthorizationPolicy
- Generating security.istio.io/v1beta1 types for AuthorizationPolicy
- Generating security.istio.io/v1beta1 types for PeerAuthentication
- Generating security.istio.io/v1 types for RequestAuthentication
- Generating security.istio.io/v1beta1 types for RequestAuthentication
- Generating telemetry.istio.io/v1alpha1 types for Telemetry

✅ Generated 23 files in the istio directory

Observe that the kubernetes-fluent-client has produced the TypeScript types within the crds directory. These types can now be utilized in the Pepr module.

user@workstation$  cat crds/proxyconfig-v1beta1.ts
// This file is auto-generated by kubernetes-fluent-client, do not edit manually

import { GenericKind, RegisterKind } from "kubernetes-fluent-client";

export class ProxyConfig extends GenericKind {
    /**
     * Provides configuration for individual workloads. See more details at:
     * https://istio.io/docs/reference/config/networking/proxy-config.html
     */
    spec?:   Spec;
    status?: { [key: string]: any };
}

/**
 * Provides configuration for individual workloads. See more details at:
 * https://istio.io/docs/reference/config/networking/proxy-config.html
 */
export interface Spec {
    /**
     * The number of worker threads to run.
     */
    concurrency?: number;
    /**
     * Additional environment variables for the proxy.
     */
    environmentVariables?: { [key: string]: string };
    /**
     * Specifies the details of the proxy image.
     */
    image?: Image;
    /**
     * Optional.
     */
    selector?: Selector;
}

/**
 * Specifies the details of the proxy image.
 */
export interface Image {
    /**
     * The image type of the image.
     */
    imageType?: string;
}

/**
 * Optional.
 */
export interface Selector {
    /**
     * One or more labels that indicate a specific set of pods/VMs on which a policy should be
     * applied.
     */
    matchLabels?: { [key: string]: string };
}

RegisterKind(ProxyConfig, {
  group: "networking.istio.io",
  version: "v1beta1",
  kind: "ProxyConfig",
});

Using new types

The generated types can be imported into Pepr directly, there is no additional logic needed to make them to work.

import { Capability, K8s, Log, a, kind } from "pepr";

import { Gateway } from "../crds/gateway-v1beta1";
import {
  PurpleDestination,
  VirtualService,
} from "../crds/virtualservice-v1beta1";

export const IstioVirtualService = new Capability({
  name: "istio-virtual-service",
  description: "Generate Istio VirtualService resources",
});

// Use the 'When' function to create a new action
const { When, Store } = IstioVirtualService;

// Define the configuration keys
enum config {
  Gateway = "uds/istio-gateway",
  Host = "uds/istio-host",
  Port = "uds/istio-port",
  Domain = "uds/istio-domain",
}

// Define the valid gateway names
const validGateway = ["admin", "tenant", "passthrough"];

// Watch Gateways to get the HTTPS domain for each gateway
When(Gateway)
  .IsCreatedOrUpdated()
  .WithLabel(config.Domain)
  .Watch(vs => {
    // Store the domain for the gateway
    Store.setItem(vs.metadata.name, vs.metadata.labels[config.Domain]);
  });

8 - OnSchedule

The OnSchedule feature allows you to schedule and automate the execution of specific code at predefined intervals or schedules. This feature is designed to simplify recurring tasks and can serve as an alternative to traditional CronJobs. This code is designed to be run at the top level on a Capability, not within a function like When.

Best Practices

OnSchedule is designed for targeting intervals equal to or larger than 30 seconds due to the storage mechanism used to archive schedule info.

Usage

Create a recurring task execution by calling the OnSchedule function with the following parameters:

name - The unique name of the schedule.

every - An integer that represents the frequency of the schedule in number of units.

unit - A string specifying the time unit for the schedule (e.g., seconds, minute, minutes, hour, hours).

startTime - (Optional) A UTC timestamp indicating when the schedule should start. All date times must be provided in GMT. If not specified the schedule will start when the schedule store reports ready.

run - A function that contains the code you want to execute on the defined schedule.

completions - (Optional) An integer indicating the maximum number of times the schedule should run to completion. If not specified the schedule will run indefinitely.

Examples

Update a ConfigMap every 30 seconds:

OnSchedule({
    name: "hello-interval",
    every: 30,
    unit: "seconds",
    run: async () => {
      Log.info("Wait 30 seconds and create/update a ConfigMap");

      try {
        await K8s(kind.ConfigMap).Apply({
          metadata: {
            name: "last-updated",
            namespace: "default",
          },
          data: {
            count: `${new Date()}`,
          },
        });

      } catch (error) {
        Log.error(error, "Failed to apply ConfigMap using server-side apply.");
      }
    },
  });

Refresh an AWSToken every 24 hours, with a delayed start of 30 seconds, running a total of 3 times:

OnSchedule({
  name: "refresh-aws-token",
  every: 24,
  unit: "hours",
  startTime: new Date(new Date().getTime() + 1000 * 30),
  run: async () => {
    await RefreshAWSToken();
  },
  completions: 3,
});

Advantages

• Simplifies scheduling recurring tasks without the need for complex CronJob configurations.
• Provides flexibility to define schedules in a human-readable format.
• Allows you to execute code with precision at specified intervals.
• Supports limiting the number of schedule completions for finite tasks.

9 - RBAC Modes

During the build phase of Pepr (npx pepr build --rbac-mode [admin|scoped]), you have the option to specify the desired RBAC mode through specific flags. This allows fine-tuning the level of access granted based on requirements and preferences.

Modes

admin

npx pepr build --rbac-mode admin

Description: The service account is given cluster-admin permissions, granting it full, unrestricted access across the entire cluster. This can be useful for administrative tasks where broad permissions are necessary. However, use this mode with caution, as it can pose security risks if misused. This is the default mode.

scoped

npx pepr build --rbac-mode scoped

Description: The service account is provided just enough permissions to perform its required tasks, and no more. This mode is recommended for most use cases as it limits potential attack vectors and aligns with best practices in security. The admission controller’s primary mutating or validating action doesn’t require a ClusterRole (as the request is not persisted or executed while passing through admission control), if you have a use case where the admission controller’s logic involves reading other Kubernetes resources or taking additional actions beyond just validating, mutating, or watching the incoming request, appropriate RBAC settings should be reflected in the ClusterRole. See how in Updating the ClusterRole.

Debugging RBAC Issues

If encountering unexpected behaviors in Pepr while running in scoped mode, check to see if they are related to RBAC.

1. Check Deployment logs for RBAC errors:

kubectl logs -n pepr-system  -l app | jq

# example output
{
  "level": 50,
  "time": 1697983053758,
  "pid": 16,
  "hostname": "pepr-static-test-watcher-745d65857d-pndg7",
  "data": {
    "kind": "Status",
    "apiVersion": "v1",
    "metadata": {},
    "status": "Failure",
    "message": "configmaps \"pepr-ssa-demo\" is forbidden: User \"system:serviceaccount:pepr-system:pepr-static-test\" cannot patch resource \"configmaps\" in API group \"\" in the namespace \"pepr-demo-2\"",
    "reason": "Forbidden",
    "details": {
      "name": "pepr-ssa-demo",
      "kind": "configmaps"
    },
    "code": 403
  },
  "ok": false,
  "status": 403,
  "statusText": "Forbidden",
  "msg": "Dooes the ServiceAccount permissions to CREATE and PATCH this ConfigMap?"
}

1. Verify ServiceAccount Permissions with kubectl auth can-i

SA=$(kubectl get deploy -n pepr-system -o=jsonpath='{range .items[0]}{.spec.template.spec.serviceAccountName}{"\n"}{end}')

# Can i create configmaps as the service account in pepr-demo-2?
kubectl auth can-i create cm --as=system:serviceaccount:pepr-system:$SA -n pepr-demo-2

# example output: no

1. Describe the ClusterRole

SA=$(kubectl get deploy -n pepr-system -o=jsonpath='{range .items[0]}{.spec.template.spec.serviceAccountName}{"\n"}{end}')

kubectl describe clusterrole $SA

# example output:
Name:         pepr-static-test
Labels:       <none>
Annotations:  <none>
PolicyRule:
  Resources            Non-Resource URLs  Resource Names  Verbs
  ---------            -----------------  --------------  -----
  peprstores.pepr.dev  []                 []              [create delete get list patch update watch]
  configmaps           []                 []              [watch]
  namespaces           []                 []              [watch]

Updating the ClusterRole

As discussed in the Modes section, the admission controller’s primary mutating or validating action doesn’t require a ClusterRole (as the request is not persisted or executed while passing through admission control), if you have a use case where the admission controller’s logic involves reading other Kubernetes resources or taking additional actions beyond just validating, mutating, or watching the incoming request, appropriate RBAC settings should be reflected in the ClusterRole.

Step 1: Figure out the desired permissions. (kubectl create clusterrole --help is a good place to start figuring out the syntax)

 kubectl create clusterrole configMapApplier --verb=create,patch --resource=configmap --dry-run=client -oyaml

 # example output
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  creationTimestamp: null
  name: configMapApplier
rules:
- apiGroups:
  - ""
  resources:
  - configmaps
  verbs:
  - create
  - patch

Step 2: Update the ClusterRole in the dist folder.

...
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: pepr-static-test
rules:
  - apiGroups:
      - pepr.dev
    resources:
      - peprstores
    verbs:
      - create
      - get
      - patch
      - watch
  - apiGroups:
      - ''
    resources:
      - namespaces
    verbs:
      - watch
  - apiGroups:
      - ''
    resources:
      - configmaps
    verbs:
      - watch
      - create # New
      - patch  # New
...

Step 3: Apply the updated configuration

10 - Metrics Endpoints

The /metrics endpoint provides metrics for the application that are collected via the MetricsCollector class. It uses the prom-client library and performance hooks from Node.js to gather and expose the metrics data in a format that can be scraped by Prometheus.

Metrics Exposed

The MetricsCollector exposes the following metrics:

• pepr_errors: A counter that increments when an error event occurs in the application.
• pepr_alerts: A counter that increments when an alert event is triggered in the application.
• pepr_mutate: A summary that provides the observed durations of mutation events in the application.
• pepr_validate: A summary that provides the observed durations of validation events in the application.
• pepr_cache_miss: A gauge that provides the number of cache misses per window.
• pepr_resync_failure_count: A gauge that provides the number of unsuccessful attempts at receiving an event within the last seen event limit before re-establishing a new connection.

Environment Variables

| PEPR_MAX_CACHE_MISS_WINDOWS | Maximum number windows to emit pepr_cache_miss metrics for | default: Undefined |

API Details

Method: GET

URL: /metrics

Response Type: text/plain

Status Codes:

• 200 OK: On success, returns the current metrics from the application.

Response Body: The response body is a plain text representation of the metrics data, according to the Prometheus exposition formats. It includes the metrics mentioned above.

Examples

Request

GET /metrics

Response

  `# HELP pepr_errors Mutation/Validate errors encountered
  # TYPE pepr_errors counter
  pepr_errors 5

  # HELP pepr_alerts Mutation/Validate bad api token received
  # TYPE pepr_alerts counter
  pepr_alerts 10

  # HELP pepr_mutate Mutation operation summary
  # TYPE pepr_mutate summary
  pepr_mutate{quantile="0.01"} 100.60707900021225
  pepr_mutate{quantile="0.05"} 100.60707900021225
  pepr_mutate{quantile="0.5"} 100.60707900021225
  pepr_mutate{quantile="0.9"} 100.60707900021225
  pepr_mutate{quantile="0.95"} 100.60707900021225
  pepr_mutate{quantile="0.99"} 100.60707900021225
  pepr_mutate{quantile="0.999"} 100.60707900021225
  pepr_mutate_sum 100.60707900021225
  pepr_mutate_count 1

  # HELP pepr_validate Validation operation summary
  # TYPE pepr_validate summary
  pepr_validate{quantile="0.01"} 201.19413900002837
  pepr_validate{quantile="0.05"} 201.19413900002837
  pepr_validate{quantile="0.5"} 201.2137690000236
  pepr_validate{quantile="0.9"} 201.23339900001884
  pepr_validate{quantile="0.95"} 201.23339900001884
  pepr_validate{quantile="0.99"} 201.23339900001884
  pepr_validate{quantile="0.999"} 201.23339900001884
  pepr_validate_sum 402.4275380000472
  pepr_validate_count 2

  # HELP pepr_cache_miss Number of cache misses per window
  # TYPE pepr_cache_miss gauge
  pepr_cache_miss{window="2024-07-25T11:54:33.897Z"} 18
  pepr_cache_miss{window="2024-07-25T12:24:34.592Z"} 0
  pepr_cache_miss{window="2024-07-25T13:14:33.450Z"} 22
  pepr_cache_miss{window="2024-07-25T13:44:34.234Z"} 19
  pepr_cache_miss{window="2024-07-25T14:14:34.961Z"} 0

  # HELP pepr_resync_failure_count Number of retries per count
  # TYPE pepr_resync_failure_count gauge
  pepr_resync_failure_count{count="0"} 5
  pepr_resync_failure_count{count="1"} 4

Prometheus Operator

If using the Prometheus Operator, the following ServiceMonitor example manifests can be used to scrape the /metrics endpoint for the admission and watcher controllers.

apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: admission
spec:
  selector:
    matchLabels:
      pepr.dev/controller: admission
  namespaceSelector:
    matchNames:
    - pepr-system
  endpoints:
  - targetPort: 3000
    scheme: https
    tlsConfig:
      insecureSkipVerify: true
---
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: watcher
spec:
  selector:
    matchLabels:
      pepr.dev/controller: watcher
  namespaceSelector:
    matchNames:
    - pepr-system
  endpoints:
  - targetPort: 3000
    scheme: https
    tlsConfig:
      insecureSkipVerify: true

11 - WASM Support

Pepr fully supports WebAssembly. Depending on the language used to generate the WASM, certain files can be too large to fit into a Secret or ConfigMap. Due to this limitation, users have the ability to incorporate *.wasm and any other essential files during the build phase, which are then embedded into the Pepr Controller container. This is achieved through adding an array of files to the includedFiles section under pepr in the package.json.

NOTE - In order to instantiate the WebAsembly module in TypeScript, you need the WebAssembly type. This is accomplished through add the “DOM” to the lib array in the compilerOptions section of the tsconfig.json. Ex: "lib": ["ES2022", "DOM"]. Be aware that adding the DOM will add a lot of extra types to your project and your developer experience will be impacted in terms of the intellisense.

High-Level Overview

WASM support is achieved through adding files as layers atop the Pepr controller image, these files are then able to be read by the individual capabilities. The key components of WASM support are:

• Add files to the base of the Pepr module.
• Reference the files in the includedFiles section of the pepr block of the package.json
• Run npx pepr build with the -r option specifying registry info. Ex: npx pepr build -r docker.io/cmwylie19
• Pepr builds and pushes a custom image that is used in the Deployment.

Using WASM Support

Creating a WASM Module in Go

Create a simple Go function that you want to call from your Pepr module

package main

import (
 "fmt"
 "syscall/js"
)

func concats(this js.Value, args []js.Value) interface{} {
    fmt.Println("PeprWASM!")
 stringOne := args[0].String()
 stringTwo := args[1].String()
 return fmt.Sprintf("%s%s", stringOne, stringTwo)
}

func main() {
 done := make(chan struct{}, 0)
 js.Global().Set("concats", js.FuncOf(concats))
 <-done
}

Compile it to a wasm target and move it to your Pepr module

GOOS=js GOARCH=wasm go build -o main.wasm
cp main.wasm $YOUR_PEPR_MODULE/

Copy the wasm_exec.js from GOROOT to your Pepr Module

cp "$(go env GOROOT)/misc/wasm/wasm_exec.js" $YOUR_PEPR_MODULE/

Update the polyfill to add globalThis.crypto in the wasm_exec.js since we are not running in the browser. This is needed directly under: (() => {

// Initialize the polyfill
if (typeof globalThis.crypto === 'undefined') {
    globalThis.crypto = {
        getRandomValues: (array) => {
        for (let i = 0; i < array.length; i++) {
            array[i] = Math.floor(Math.random() * 256);
        }
        },
    };
}

Configure Pepr to use WASM

After adding the files to the root of the Pepr module, reference those files in the package.json:

{
  "name": "pepr-test-module",
  "version": "0.0.1",
  "description": "A test module for Pepr",
  "keywords": [
    "pepr",
    "k8s",
    "policy-engine",
    "pepr-module",
    "security"
  ],
  "engines": {
    "node": ">=18.0.0"
  },
  "pepr": {
    "name": "pepr-test-module",
    "uuid": "static-test",
    "onError": "ignore",
    "alwaysIgnore": {
      "namespaces": [],
      "labels": []
    },
    "includedFiles":[
      "main.wasm",
      "wasm_exec.js"
    ]
  },
  ...
}

Update the tsconfig.json to add “DOM” to the compilerOptions lib:

{
  "compilerOptions": {
    "allowSyntheticDefaultImports": true,
    "declaration": true,
    "declarationMap": true,
    "emitDeclarationOnly": true,
    "esModuleInterop": true,
    "lib": [
      "ES2022",
      "DOM" // <- Add this
    ],
    "module": "CommonJS",
    "moduleResolution": "node",
    "outDir": "dist",
    "resolveJsonModule": true,
    "rootDir": ".",
    "strict": false,
    "target": "ES2022",
    "useUnknownInCatchVariables": false
  },
  "include": [
    "**/*.ts"
  ]
}

Call WASM functions from TypeScript

Import the wasm_exec.js in the pepr.ts

import "./wasm_exec.js";

Create a helper function to load the wasm file in a capability and call it during an event of your choice

async function callWASM(a,b) {
  const go = new globalThis.Go();

  const wasmData = readFileSync("main.wasm");
  var concated: string;

  await WebAssembly.instantiate(wasmData, go.importObject).then(wasmModule => {
    go.run(wasmModule.instance);

    concated = global.concats(a,b);
  });
  return concated;
}

When(a.Pod)
.IsCreated()
.Mutate(async pod => {
  try {
    let label_value = await callWASM("loves","wasm")
    pod.SetLabel("pepr",label_value)
  }
  catch(err) {
    Log.error(err);
  }
});

Run Pepr Build

Build your Pepr module with the registry specified.

npx pepr build -r docker.io/defenseunicorns

12 - Customization

This document outlines how to customize the build output through Helm overrides and package.json configurations.

Redact Store Values from Logs

By default, the store values are displayed in logs, to redact them you can set the PEPR_STORE_REDACT_VALUES environment variable to true in the package.json file or directly on the Watcher or Admission Deployment. The default value is undefined.

{
  "env": {
    "PEPR_STORE_REDACT_VALUES": "true"
  }
}

Display Node Warnings

You can display warnings in the logs by setting the PEPR_NODE_WARNINGS environment variable to true in the package.json file or directly on the Watcher or Admission Deployment. The default value is undefined.

{
  "env": {
    "PEPR_NODE_WARNINGS": "true"
  }
}

Customizing Log Format

The log format can be customized by setting the PINO_TIME_STAMP environment variable in the package.json file or directly on the Watcher or Admission Deployment. The default value is a partial JSON timestamp string representation of the time. If set to iso, the timestamp is displayed in an ISO format.

Caution: attempting to format time in-process will significantly impact logging performance.

{
  "env": {
    "PINO_TIME_STAMP": "iso"
  }
}

With ISO:

{"level":30,"time":"2024-05-14T14:26:03.788Z","pid":16,"hostname":"pepr-static-test-7f4d54b6cc-9lxm6","method":"GET","url":"/healthz","status":200,"duration":"1 ms"}

Default (without):

{"level":30,"time":"1715696764106","pid":16,"hostname":"pepr-static-test-watcher-559d94447f-xkq2h","method":"GET","url":"/healthz","status":200,"duration":"1 ms"}

Customizing Watch Configuration

The Watch configuration is a part of the Pepr module that allows you to watch for specific resources in the Kubernetes cluster. The Watch configuration can be customized by specific enviroment variables of the Watcher Deployment and can be set in the field in the package.json or in the helm values.yaml file.

Configuring Reconcile

The Reconcile Action allows you to maintain ordering of resource updates processed by a Pepr controller. The Reconcile configuration can be customized via enviroment variable on the Watcher Deployment, which can be set in the package.json or in the helm values.yaml file.

Customizing with Helm

Below are the available Helm override configurations after you have built your Pepr module that you can put in the values.yaml.

Helm Overrides Table

Admission and Watcher Subparameters

Note: Replace * within admission.* or watcher.* to apply settings specific to the desired subparameter (e.g. admission.failurePolicy).

Customizing with package.json

Below are the available configurations through package.json.

package.json Configurations Table

These tables provide a comprehensive overview of the fields available for customization within the Helm overrides and the package.json file. Modify these according to your deployment requirements.

Example Custom RBAC Rules

The following example demonstrates how to add custom RBAC rules to the Pepr module.

{
  "pepr": {
    "rbac": [
      {
        "apiGroups": ["pepr.dev"],
        "resources": ["customresources"],
        "verbs": ["get", "list"]
      },
      {
        "apiGroups": ["apps"],
        "resources": ["deployments"],
        "verbs": ["create", "delete"]
      }
    ]
  }
}

13 - Pepr Filters

Filters are functions that take a AdmissionReview or Watch event and return a boolean. They are used to filter out resources that do not meet certain criteria. Filters are used in the package to filter out resources that are not relevant to the user-defined admission or watch process.

When(a.ConfigMap)
  // This limits the action to only act on new resources.
  .IsCreated()
  // Namespace filter
  .InNamespace("webapp")
  // Name filter
  .WithName("example-1")
  // Label filter
  .WithLabel("app", "webapp")
  .WithLabel("env", "prod")
  .Mutate(request => {
    request
      .SetLabel("pepr", "was-here")
      .SetAnnotation("pepr.dev", "annotations-work-too");
  });

Filters

• .WithName("name"): Filters resources by name.
• .WithNameRegex(/^pepr/): Filters resources by name using a regex.
• .InNamespace("namespace"): Filters resources by namespace.
• .InNamespaceRegex(/(.*)-system/): Filters resources by namespace using a regex.
• .WithLabel("key", "value"): Filters resources by label. (Can be multiple)
• .WithDeletionTimestamp(): Filters resources that have a deletion timestamp.

Notes:

• WithDeletionTimestamp() is does not work on Delete through the Mutate or Validate methods because the Kubernetes Admission Process does not fire the DELETE event with a deletion timestamp on the resource.
• WithDeletionTimestamp() will match on an Update event during Admission (Mutate or Validate) when pending-deletion permitted changes (like removing a finalizer) occur.