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BuildRun

Overview

The resource BuildRun (buildruns.shipwright.io/v1beta1) is the build process of a Build resource definition executed in Kubernetes.

A BuildRun resource allows the user to define:

  • The BuildRun name, through which the user can monitor the status of the image construction.
  • A referenced Build instance to use during the build construction.
  • A service account for hosting all related secrets to build the image.

A BuildRun is available within a namespace.

BuildRun Controller

The controller watches for:

  • Updates on a Build resource (CRD instance)
  • Updates on a TaskRun resource (CRD instance)

When the controller reconciles it:

  • Looks for any existing owned TaskRuns and updates its parent BuildRun status.
  • Retrieves the specified SA and sets this with the specify output secret on the Build resource.
  • If one does not exist, it generates a new tekton TaskRun and sets a reference to this resource(as a child of the controller).
  • On any subsequent updates on the TaskRun, the controller will update the parent BuildRun resource instance.

Configuring a BuildRun

The BuildRun definition supports the following fields:

  • Required:

    • apiVersion - Specifies the API version, for example shipwright.io/v1beta1.
    • kind - Specifies the Kind type, for example BuildRun.
    • metadata - Metadata that identify the CRD instance, for example the name of the BuildRun.

  • Optional:

    • spec.build.name - Specifies an existing Build resource instance to use.
    • spec.build.spec - Specifies an embedded (transient) Build resource to use.
    • spec.serviceAccount - Refers to the SA to use when building the image. (defaults to the default SA)
    • spec.timeout - Defines a custom timeout. The value needs to be parsable by ParseDuration, for example, 5m. The value overwrites the value that is defined in the Build.
    • spec.paramValues - Refers to a name-value(s) list to specify values for parameters defined in the BuildStrategy. This value overwrites values defined with the same name in the Build.
    • spec.output.image - Refers to a custom location where the generated image would be pushed. The value will overwrite the output.image value defined in Build. (Note: other properties of the output, for example, the credentials, cannot be specified in the buildRun spec. )
    • spec.output.pushSecret - Reference an existing secret to get access to the container registry. This secret will be added to the service account along with the ones requested by the Build.
    • spec.output.timestamp - Overrides the output timestamp configuration of the referenced build to instruct the build to change the output image creation timestamp to the specified value. When omitted, the respective build strategy tool defines the output image timestamp.
    • spec.env - Specifies additional environment variables that should be passed to the build container. Overrides any environment variables that are specified in the Build resource. The available variables depend on the tool used by the chosen build strategy.

Note: The spec.build.name and spec.build.spec are mutually exclusive. Furthermore, the overrides for timeout, paramValues, output, and env can only be combined with spec.build.name, but not with spec.build.spec.

Defining the Build Reference

A BuildRun resource can reference a Build resource, that indicates what image to build. For example:

apiVersion: shipwright.io/v1beta1
kind: BuildRun
metadata:
  name: buildpack-nodejs-buildrun-namespaced
spec:
  build:
    name: buildpack-nodejs-build-namespaced

Defining the Build Specification

A complete BuildSpec can be embedded into the BuildRun for the build.

apiVersion: shipwright.io/v1beta1
kind: BuildRun
metadata:
  name: standalone-buildrun
spec:
  build:
    spec:
      source:
        type: Git
        git:
          url: https://github.com/shipwright-io/sample-go.git
        contextDir: source-build
      strategy:
        kind: ClusterBuildStrategy
        name: buildpacks-v3
      output:
        image: foo/bar:latest

Defining the Build Source

BuildRun's support the specification of a Local type source. This is useful for working on development mode, without forcing a user to commit/push changes to their related version control system. For more information please refer to SHIP 0016 - enabling local source code.

apiVersion: shipwright.io/v1beta1
kind: BuildRun
metadata:
  name: local-buildrun
spec:
  build:
    name: a-build
  source:
    type: Local
    local:
      name: local-source
      timeout: 3m

Defining ParamValues

A BuildRun resource can define paramValues for parameters specified in the build strategy. If a value has been provided for a parameter with the same name in the Build already, then the value from the BuildRun will have precedence.

For example, the following BuildRun overrides the value for sleep-time param, which is defined in the a-build Build resource.

---
apiVersion: shipwright.io/v1beta1
kind: Build
metadata:
  name: a-build
  namespace: a-namespace
spec:
  paramValues:
  - name: cache
    value: disabled
  strategy:
    name: buildkit
    kind: ClusterBuildStrategy
  source:
  ...
  output:
  ...

---
apiVersion: shipwright.io/v1beta1
kind: BuildRun
metadata:
  name: a-buildrun
  namespace: a-namespace
spec:
  build:
    name: a-build
  paramValues:
  - name: cache
    value: registry

See more about paramValues usage in the related Build resource docs.

Defining the ServiceAccount

A BuildRun resource can define a serviceaccount to use. Usually this SA will host all related secrets referenced on the Build resource, for example:

apiVersion: shipwright.io/v1beta1
kind: BuildRun
metadata:
  name: buildpack-nodejs-buildrun-namespaced
spec:
  build:
    name: buildpack-nodejs-build-namespaced
  serviceAccount: pipeline

You can also set the value of spec.serviceAccount to ".generate". This will generate the service account during runtime for you. The name of the generated service account is the same as that of the BuildRun.

Note: When the service account is not defined, the BuildRun uses the pipeline service account if it exists in the namespace, and falls back to the default service account.

Defining Retention Parameters

A Buildrun resource can specify how long a completed BuildRun can exist. Instead of manually cleaning up old BuildRuns, retention parameters provide an alternate method for cleaning up BuildRuns automatically.

As part of the buildrun retention parameters, we have the following fields:

  • retention.ttlAfterFailed - Specifies the duration for which a failed buildrun can exist.
  • retention.ttlAfterSucceeded - Specifies the duration for which a successful buildrun can exist.

An example of a user using buildrun TTL parameters.

apiVersion: shipwright.io/v1beta1
kind: BuildRun
metadata:
  name: buidrun-retention-ttl
spec:
  build:
    name: build-retention-ttl
  retention:
    ttlAfterFailed: 10m
    ttlAfterSucceeded: 10m

Note: In case TTL values are defined in buildrun specifications as well as build specifications, priority will be given to the values defined in the buildrun specifications.

Defining Volumes

BuildRuns can declare volumes. They must override volumes defined by the according BuildStrategy. If a volume is not overridable then the BuildRun will eventually fail.

In case Build and BuildRun that refers to this Build override the same volume, one that is defined in the BuildRun is the one used eventually.

Volumes follow the declaration of Pod Volumes, so all the usual volumeSource types are supported.

Here is an example of BuildRun object that overrides volumes:

apiVersion: shipwright.io/v1beta1
kind: BuildRun
metadata:
  name: buildrun-name
spec:
  build:
    name: build-name
  volumes:
    - name: volume-name
      configMap:
        name: test-config

Canceling a BuildRun

To cancel a BuildRun that's currently executing, update its status to mark it as canceled.

When you cancel a BuildRun, the underlying TaskRun is marked as canceled per the Tekton cancel TaskRun feature.

Example of canceling a BuildRun:

apiVersion: shipwright.io/v1beta1
kind: BuildRun
metadata:
  name: buildpack-nodejs-buildrun-namespaced
spec:
  # [...]
  state: "BuildRunCanceled"

Automatic BuildRun deletion

We have two controllers that ensure that buildruns can be deleted automatically if required. This is ensured by adding retention parameters in either the build specifications or the buildrun specifications.

  • Buildrun TTL parameters: These are used to make sure that buildruns exist for a fixed duration of time after completiion.
    • buildrun.spec.retention.ttlAfterFailed: The buildrun is deleted if the mentioned duration of time has passed and the buildrun has failed.
    • buildrun.spec.retention.ttlAfterSucceeded: The buildrun is deleted if the mentioned duration of time has passed and the buildrun has succeeded.
  • Build TTL parameters: These are used to make sure that related buildruns exist for a fixed duration of time after completion.
    • build.spec.retention.ttlAfterFailed: The buildrun is deleted if the mentioned duration of time has passed and the buildrun has failed.
    • build.spec.retention.ttlAfterSucceeded: The buildrun is deleted if the mentioned duration of time has passed and the buildrun has succeeded.
  • Build Limit parameters: These are used to make sure that related buildruns exist for a fixed duration of time after completiion.
    • build.spec.retention.succeededLimit - Defines number of succeeded BuildRuns for a Build that can exist.
    • build.spec.retention.failedLimit - Defines number of failed BuildRuns for a Build that can exist.

Specifying Environment Variables

An example of a BuildRun that specifies environment variables:

apiVersion: shipwright.io/v1beta1
kind: BuildRun
metadata:
  name: buildpack-nodejs-buildrun-namespaced
spec:
  build:
    name: buildpack-nodejs-build-namespaced
  env:
    - name: EXAMPLE_VAR_1
      value: "example-value-1"
    - name: EXAMPLE_VAR_2
      value: "example-value-2"

Example of a BuildRun that uses the Kubernetes Downward API to expose a Pod field as an environment variable:

apiVersion: shipwright.io/v1beta1
kind: BuildRun
metadata:
  name: buildpack-nodejs-buildrun-namespaced
spec:
  build:
    name: buildpack-nodejs-build-namespaced
  env:
    - name: POD_NAME
      valueFrom:
        fieldRef:
          fieldPath: metadata.name

Example of a BuildRun that uses the Kubernetes Downward API to expose a Container field as an environment variable:

apiVersion: shipwright.io/v1beta1
kind: BuildRun
metadata:
  name: buildpack-nodejs-buildrun-namespaced
spec:
  build:
    name: buildpack-nodejs-build-namespaced
  env:
    - name: MEMORY_LIMIT
      valueFrom:
        resourceFieldRef:
          containerName: my-container
          resource: limits.memory

BuildRun Status

The BuildRun resource is updated as soon as the current image building status changes:

$ kubectl get buildrun buildpacks-v3-buildrun
NAME                    SUCCEEDED   REASON    MESSAGE   STARTTIME   COMPLETIONTIME
buildpacks-v3-buildrun  Unknown     Pending   Pending   1s

And finally:

$ kubectl get buildrun buildpacks-v3-buildrun
NAME                    SUCCEEDED   REASON      MESSAGE                              STARTTIME   COMPLETIONTIME
buildpacks-v3-buildrun  True        Succeeded   All Steps have completed executing   4m28s       16s

The above allows users to get an overview of the building mechanism state.

Understanding the state of a BuildRun

A BuildRun resource stores the relevant information regarding the object's state under status.conditions.

Conditions allow users to quickly understand the resource state without needing to understand resource-specific details.

For the BuildRun, we use a Condition of the type Succeeded, which is a well-known type for resources that run to completion.

The status.conditions hosts different fields, like status, reason and message. Users can expect these fields to be populated with relevant information.

The following table illustrates the different states a BuildRun can have under its status.conditions:

Status Reason CompletionTime is set Description
Unknown Pending No The BuildRun is waiting on a Pod in status Pending.
Unknown Running No The BuildRun has been validated and started to perform its work.
Unknown Running No The BuildRun has been validated and started to perform its work.
Unknown BuildRunCanceled No The user requested the BuildRun to be canceled. This results in the BuildRun controller requesting the TaskRun be canceled. Cancellation has not been done yet.
True Succeeded Yes The BuildRun Pod is done.
False Failed Yes The BuildRun failed in one of the steps.
False BuildRunTimeout Yes The BuildRun timed out.
False UnknownStrategyKind Yes The Build specified strategy Kind is unknown. (options: ClusterBuildStrategy or BuildStrategy)
False ClusterBuildStrategyNotFound Yes The referenced cluster strategy was not found in the cluster.
False BuildStrategyNotFound Yes The referenced namespaced strategy was not found in the cluster.
False SetOwnerReferenceFailed Yes Setting ownerreferences from the BuildRun to the related TaskRun failed.
False TaskRunIsMissing Yes The BuildRun related TaskRun was not found.
False TaskRunGenerationFailed Yes The generation of a TaskRun spec failed.
False MissingParameterValues Yes No value has been provided for some parameters that are defined in the build strategy without any default. Values for those parameters must be provided through the Build or the BuildRun.
False RestrictedParametersInUse Yes A value for a system parameter was provided. This is not allowed.
False UndefinedParameter Yes A value for a parameter was provided that is not defined in the build strategy.
False WrongParameterValueType Yes A value was provided for a build strategy parameter using the wrong type. The parameter is defined as array or string in the build strategy. Depending on that, you must provide values or a direct value.
False InconsistentParameterValues Yes A value for a parameter contained more than one of value, configMapValue, and secretValue. Any values including array items must only provide one of them.
False EmptyArrayItemParameterValues Yes An item inside the values of an array parameter contained none of value, configMapValue, and secretValue. Exactly one of them must be provided. Null array items are not allowed.
False IncompleteConfigMapValueParameterValues Yes A value for a parameter contained a configMapValue where the name or the value were empty. You must specify them to point to an existing ConfigMap key in your namespace.
False IncompleteSecretValueParameterValues Yes A value for a parameter contained a secretValue where the name or the value were empty. You must specify them to point to an existing Secret key in your namespace.
False ServiceAccountNotFound Yes The referenced service account was not found in the cluster.
False BuildRegistrationFailed Yes The related Build in the BuildRun is in a Failed state.
False BuildNotFound Yes The related Build in the BuildRun was not found.
False BuildRunCanceled Yes The BuildRun and underlying TaskRun were canceled successfully.
False BuildRunNameInvalid Yes The defined BuildRun name (metadata.name) is invalid. The BuildRun name should be a valid label value.
False BuildRunNoRefOrSpec Yes BuildRun does not have either spec.build.name or spec.build.spec defined. There is no connection to a Build specification.
False BuildRunAmbiguousBuild Yes The defined BuildRun uses both spec.build.name and spec.build.spec. Only one of them is allowed at the same time.
False BuildRunBuildFieldOverrideForbidden Yes The defined BuildRun uses an override (e.g. timeout, paramValues, output, or env) in combination with spec.build.spec, which is not allowed. Use the spec.build.spec to directly specify the respective value.
False PodEvicted Yes The BuildRun Pod was evicted from the node it was running on. See API-initiated Eviction and Node-pressure Eviction for more information.
False StepOutOfMemory Yes The BuildRun Pod failed because a step went out of memory.

Note: We heavily rely on the Tekton TaskRun Conditions for populating the BuildRun ones, with some exceptions.

Understanding failed BuildRuns

To make it easier for users to understand why did a BuildRun failed, users can infer the pod and container where the failure took place from the status.failureDetails field.

In addition, the status.conditions hosts a compacted message under the message field that contains the kubectl command to trigger and retrieve the logs.

The status.failureDetails field also includes a detailed failure reason and message, if the build strategy provides them.

Example of failed BuildRun:

# [...]
status:
  # [...]
  failureDetails:
    location:
      container: step-source-default
      pod: baran-build-buildrun-gzmv5-b7wbf-pod-bbpqr
    message: The source repository does not exist, or you have insufficient permission
      to access it.
    reason: GitRemotePrivate

Understanding failed git-source step

All git-related operations support error reporting via status.failureDetails. The following table explains the possible error reasons:

Reason Description
GitAuthInvalidUserOrPass Basic authentication has failed. Check your username or password. Note: GitHub requires a personal access token instead of your regular password.
GitAuthInvalidKey The key is invalid for the specified target. Please make sure that the Git repository exists, you have sufficient permissions, and the key is in the right format.
GitRevisionNotFound The remote revision does not exist. Check the revision specified in your Build.
GitRemoteRepositoryNotFound The source repository does not exist, or you have insufficient permissions to access it.
GitRemoteRepositoryPrivate You are trying to access a non-existing or private repository without having sufficient permissions to access it via HTTPS.
GitBasicAuthIncomplete Basic Auth incomplete: Both username and password must be configured.
GitSSHAuthUnexpected Credential/URL inconsistency: SSH credentials were provided, but the URL is not an SSH Git URL.
GitSSHAuthExpected Credential/URL inconsistency: No SSH credentials provided, but the URL is an SSH Git URL.
GitError The specific error reason is unknown. Check the error message for more information.

Step Results in BuildRun Status

After completing a BuildRun, the .status field contains the results (.status.taskResults) emitted from the TaskRun steps generated by the BuildRun controller as part of processing the BuildRun. These results contain valuable metadata for users, like the image digest or the commit sha of the source code used for building. The results from the source step will be surfaced to the .status.sources, and the results from the output step will be surfaced to the .status.output field of a BuildRun.

Example of a BuildRun with surfaced results for git source (note that the branchName is only included if the Build does not specify any revision):

# [...]
status:
  buildSpec:
    # [...]
  output:
    digest: sha256:07626e3c7fdd28d5328a8d6df8d29cd3da760c7f5e2070b534f9b880ed093a53
    size: 1989004
  sources:
  - name: default
    git:
      commitAuthor: xxx xxxxxx
      commitSha: f25822b85021d02059c9ac8a211ef3804ea8fdde
      branchName: main

Another example of a BuildRun with surfaced results for local source code(ociArtifact) source:

# [...]
status:
  buildSpec:
    # [...]
  output:
    digest: sha256:07626e3c7fdd28d5328a8d6df8d29cd3da760c7f5e2070b534f9b880ed093a53
    size: 1989004
  sources:
  - name: default
    ociArtifact:
      digest: sha256:0f5e2070b534f9b880ed093a537626e3c7fdd28d5328a8d6df8d29cd3da760c7

Note: The digest and size of the output image are only included if the build strategy provides them. See System results.

Build Snapshot

For every BuildRun controller reconciliation, the buildSpec in the status of the BuildRun is updated if an existing owned TaskRun is present. During this update, a Build resource snapshot is generated and embedded into the status.buildSpec path of the BuildRun. A buildSpec is just a copy of the original Build spec, from where the BuildRun executed a particular image build. The snapshot approach allows developers to see the original Build configuration.

Relationship with Tekton Tasks

The BuildRun resource abstracts the image construction by delegating this work to the Tekton Pipeline TaskRun. Compared to a Tekton Pipeline Task, a TaskRun runs all steps until completion of the Task or until a failure occurs in the Task.

During the Reconcile, the BuildRun controller will generate a new TaskRun. The controller will embed in the TaskRun Task definition the requires steps to execute during the execution. These steps are defined in the strategy defined in the Build resource, either a ClusterBuildStrategy or a BuildStrategy.