With Red Hat OpenShift Pipelines, you can create a customized CI/CD solution to build, test, and deploy your application.

To create a full-fledged, self-serving CI/CD Pipeline for an application, you must perform the following tasks:

  • Create custom Tasks, or install existing reusable Tasks.

  • Create and define the delivery Pipeline for your application.

  • Create a PersistentVolumeClaim attached to the Workspace to provide the volume or filesystem for Pipeline execution.

  • Create a PipelineRun to instantiate and invoke the Pipeline.

  • Add Triggers to capture any events in the source repository.

This section uses the pipelines-tutorial example to demonstrate the preceding tasks. The example uses a simple application which consists of:

  • A front-end interface, vote-ui, with the source code in the ui-repo Git repository.

  • A back-end interface, vote-api, with the source code in the api-repo Git repository.

  • The apply_manifest and update-deployment Tasks in the pipelines-tutorial Git repository.

Prerequisites

  • You have access to an OKD cluster.

  • You have installed OpenShift Pipelines using the Red Hat OpenShift Pipelines Operator listed in the OpenShift OperatorHub. Once installed, it is applicable to the entire cluster.

  • You have installed OpenShift Pipelines CLI.

  • You have forked the front-end ui-repo and back-end api-repo Git repositories using your GitHub ID, and have Administrator access to these repositories.

  • Optional: You have cloned the pipelines-tutorial Git repository.

Creating a project and checking your Pipeline ServiceAccount

Procedure
  1. Log in to your OKD cluster:

    $ oc login -u <login> -p <password> https://openshift.example.com:6443
  2. Create a project for the sample application. For this example workflow, create the pipelines-tutorial project:

    $ oc new-project pipelines-tutorial

    If you create a project with a different name, be sure to update the resource URLs used in the example with your project name.

  3. View the pipeline ServiceAccount:

    Red Hat OpenShift Pipelines Operator adds and configures a ServiceAccount named pipeline that has sufficient permissions to build and push an image. This ServiceAccount is used by PipelineRun.

    $ oc get serviceaccount pipeline

Creating Pipeline Tasks

Procedure
  1. Install the apply-manifests and update-deployment Tasks from the pipelines-tutorial repository, which contains a list of reusable Tasks for Pipelines:

    $ oc create -f https://raw.githubusercontent.com/openshift/pipelines-tutorial/release-tech-preview-2/01_pipeline/01_apply_manifest_task.yaml
    $ oc create -f https://raw.githubusercontent.com/openshift/pipelines-tutorial/release-tech-preview-2/01_pipeline/02_update_deployment_task.yaml
  2. Use the tkn task list command to list the Tasks you created:

    $ tkn task list

    The output verifies that the apply-manifests and update-deployment Tasks were created:

    NAME                DESCRIPTION   AGE
    apply-manifests                   1 minute ago
    update-deployment                 48 seconds ago
  3. Use the tkn clustertasks list command to list the Operator-installed additional ClusterTasks, for example --buildah and s2i-python-3:

    You must use a privileged Pod container to run the buildah ClusterTask because it requires a privileged security context. To learn more about Security Context Constraints (SCC) for Pods, see the Additional resources section.

    $ tkn clustertasks list

    The output lists the Operator-installed ClusterTasks:

    NAME                       DESCRIPTION   AGE
    buildah                                  1 day ago
    git-clone                                1 day ago
    s2i-php                                  1 day ago
    tkn                                      1 day ago

Assembling a Pipeline

A Pipeline represents a CI/CD flow and is defined by the Tasks to be executed. It is designed to be generic and reusable in multiple applications and environments.

A Pipeline specifies how the Tasks interact with each other and their order of execution using the from and runAfter parameters. It uses the workspaces field to specify one or more volumes that each Task in the Pipeline requires during execution.

In this section, you will create a Pipeline that takes the source code of the application from GitHub and then builds and deploys it on OKD.

The Pipeline performs the following tasks for the back-end application vote-api and front-end application vote-ui:

  • Clones the source code of the application from the Git repository by referring to the git-url and git-revision parameters.

  • Builds the container image using the buildah ClusterTask.

  • Pushes the image to the internal image registry by referring to the image parameter.

  • Deploys the new image on OKD by using the apply-manifests and update-deployment Tasks.

Procedure
  1. Copy the contents of the following sample Pipeline YAML file and save it:

    apiVersion: tekton.dev/v1beta1
    kind: Pipeline
    metadata:
      name: build-and-deploy
    spec:
      workspaces:
      - name: shared-workspace
      params:
      - name: deployment-name
        type: string
        description: name of the deployment to be patched
      - name: git-url
        type: string
        description: url of the git repo for the code of deployment
      - name: git-revision
        type: string
        description: revision to be used from repo of the code for deployment
        default: "release-tech-preview-2"
      - name: IMAGE
        type: string
        description: image to be build from the code
      tasks:
      - name: fetch-repository
        taskRef:
          name: git-clone
          kind: ClusterTask
        workspaces:
        - name: output
          workspace: shared-workspace
        params:
        - name: url
          value: $(params.git-url)
        - name: subdirectory
          value: ""
        - name: deleteExisting
          value: "true"
        - name: revision
          value: $(params.git-revision)
      - name: build-image
        taskRef:
          name: buildah
          kind: ClusterTask
        params:
        - name: TLSVERIFY
          value: "false"
        - name: IMAGE
          value: $(params.IMAGE)
        workspaces:
        - name: source
          workspace: shared-workspace
        runAfter:
        - fetch-repository
      - name: apply-manifests
        taskRef:
          name: apply-manifests
        workspaces:
        - name: source
          workspace: shared-workspace
        runAfter:
        - build-image
      - name: update-deployment
        taskRef:
          name: update-deployment
        workspaces:
        - name: source
          workspace: shared-workspace
        params:
        - name: deployment
          value: $(params.deployment-name)
        - name: IMAGE
          value: $(params.IMAGE)
        runAfter:
        - apply-manifests

    The Pipeline definition abstracts away the specifics of the Git source repository and image registries. These details are added as params when a Pipeline is triggered and executed.

  2. Create the Pipeline:

    $ oc create -f <pipeline-yaml-file-name.yaml>

    Alternatively, you can also execute the YAML file directly from the Git repository:

    $ oc create -f https://raw.githubusercontent.com/openshift/pipelines-tutorial/release-tech-preview-2/01_pipeline/04_pipeline.yaml
  3. Use the tkn pipeline list command to verify that the Pipeline is added to the application:

    $ tkn pipeline list

    The output verifies that the build-and-deploy Pipeline was created:

    NAME               AGE            LAST RUN   STARTED   DURATION   STATUS
    build-and-deploy   1 minute ago   ---        ---       ---        ---

Specifying PersistentVolumeClaims as VolumeSource in Workspaces

Workspaces help Tasks share data, and allow you to specify one or more volumes that each Task in the Pipeline requires during execution.

In this section, you will create a PersistentVolumeClaim to provide data storage and bind it to the Workspace. This PersistentVolumeClaim provides the volumes or filesystem required for the Pipeline execution.

Procedure
  1. Copy and save the contents of the following sample PersistentVolumeClaim YAML file:

    apiVersion: v1
    kind: PersistentVolumeClaim
    metadata:
      name: source-pvc
    spec:
      accessModes:
        - ReadWriteOnce
      resources:
        requests:
          storage: 500Mi
  2. Create the PersistentVolumeClaim, specifying the file you just created:

    $ oc create -f <PersistentVolumeClaim-yaml-file-name.yaml>

    Alternatively, you can execute the YAML file directly from the Git repository:

    $ oc create -f https://raw.githubusercontent.com/openshift/pipelines-tutorial/release-tech-preview-2/01_pipeline/03_persistent_volume_claim.yaml

Running a Pipeline

A PipelineRun starts a Pipeline and ties it to the Git and image resources that should be used for the specific invocation. It automatically creates and starts the TaskRuns for each Task in the Pipeline.

Procedure
  1. Start the Pipeline for the back-end application:

    $ tkn pipeline start build-and-deploy -w name=shared-workspace,claimName=source-pvc -p deployment-name=vote-api -p git-url=http://github.com/openshift-pipelines/vote-api.git -p IMAGE=image-registry.openshift-image-registry.svc:5000/pipelines-tutorial/vote-api

    Note the PipelineRun ID returned in the command output.

  2. Track the PipelineRun progress:

    $ tkn pipelinerun logs <pipelinerun ID> -f
  3. Start the Pipeline for the front-end application:

    $ tkn pipeline start build-and-deploy -w name=shared-workspace,claimName=source-pvc -p deployment-name=vote-api -p git-url=http://github.com/openshift-pipelines/vote-ui.git -p IMAGE=image-registry.openshift-image-registry.svc:5000/pipelines-tutorial/vote-ui

    Note the PipelineRun ID returned in the command output.

  4. Track the PipelineRun progress:

    $ tkn pipelinerun logs <pipelinerun ID> -f
  5. After a few minutes, use tkn pipelinerun list command to verify that the Pipeline ran successfully by listing all the PipelineRuns:

    $ tkn pipelinerun list

    The output lists the PipelineRuns:

     NAME                         STARTED      DURATION     STATUS
     build-and-deploy-run-xy7rw   1 hour ago   2 minutes    Succeeded
     build-and-deploy-run-z2rz8   1 hour ago   19 minutes   Succeeded
  6. Get the application route:

    $ oc get route vote-ui --template='http://{{.spec.host}}'

    Note the output of the previous command. You can access the application using this route.

  7. To rerun the last PipelineRun, using the PipelineResources and ServiceAccount of the previous Pipeline, run:

    $ tkn pipeline start build-and-deploy --last

Adding Triggers to a Pipeline

Triggers enable Pipelines to respond to external GitHub events, such as push events and pull requests. After you have assembled and started the Pipeline for the application, add TriggerBindings, TriggerTemplates, and an EventListener to capture the GitHub events.

Procedure
  1. Copy the content of the following sample TriggerBinding YAML file and save it:

    apiVersion: triggers.tekton.dev/v1alpha1
    kind: TriggerBinding
    metadata:
      name: vote-app
    spec:
      params:
      - name: git-repo-url
        value: $(body.repository.url)
      - name: git-repo-name
        value: $(body.repository.name)
      - name: git-revision
        value: $(body.head_commit.id)
  2. Create the TriggerBinding:

    $ oc create -f <triggerbinding-yaml-file-name.yaml>

    Alternatively, you can create the TriggerBinding directly from the pipelines-tutorial Git repository:

    $ oc create -f https://raw.githubusercontent.com/openshift/pipelines-tutorial/release-tech-preview-2/03_triggers/01_binding.yaml
  3. Copy the content of the following sample TriggerTemplate YAML file and save it:

    apiVersion: triggers.tekton.dev/v1alpha1
    kind: TriggerTemplate
    metadata:
      name: vote-app
    spec:
      params:
      - name: git-repo-url
        description: The git repository url
      - name: git-revision
        description: The git revision
        default: release-tech-preview-2
      - name: git-repo-name
        description: The name of the deployment to be created / patched
    
      resourcetemplates:
      - apiVersion: tekton.dev/v1beta1
        kind: PipelineRun
        metadata:
          name: build-deploy-$(tt.params.git-repo-name)-$(uid)
        spec:
          serviceAccountName: pipeline
          pipelineRef:
            name: build-and-deploy
          params:
          - name: deployment-name
            value: $(tt.params.git-repo-name)
          - name: git-url
            value: $(tt.params.git-repo-url)
          - name: git-revision
            value: $(tt.params.git-revision)
          - name: IMAGE
            value: image-registry.openshift-image-registry.svc:5000/pipelines-tutorial/$(tt.params.git-repo-name)
          workspaces:
          - name: shared-workspace
            persistentvolumeclaim:
              claimName: source-pvc
  4. Create the TriggerTemplate:

    $ oc create -f <triggertemplate-yaml-file-name.yaml>

    Alternatively, you can create the TriggerTemplate directly from the pipelines-tutorial Git repository:

    $ oc create -f https://raw.githubusercontent.com/openshift/pipelines-tutorial/release-tech-preview-2/03_triggers/02_template.yaml
  5. Copy the contents of the following sample EventListener YAML file and save it:

    apiVersion: triggers.tekton.dev/v1alpha1
    kind: EventListener
    metadata:
      name: vote-app
    spec:
      serviceAccountName: pipeline
      triggers:
      - bindings:
        - name: vote-app
        template:
          name: vote-app
  6. Create the EventListener:

    $ oc create -f <eventlistener-yaml-file-name.yaml>

    Alternatively, you can create the EvenListener directly from the pipelines-tutorial Git repository:

    $ oc create -f https://raw.githubusercontent.com/openshift/pipelines-tutorial/release-tech-preview-2/03_triggers/03_event_listener.yaml
  7. Expose the EventListener service as an OKD route to make it publicly accessible:

    $ oc expose svc el-vote-app

Creating Webhooks

Webhooks are HTTP POST messages that are received by the EventListeners whenever a configured event occurs in your repository. The event payload is then mapped to TriggerBindings, and processed by TriggerTemplates. The TriggerTemplates eventually start one or more PipelineRuns, leading to the creation and deployment of Kubernetes resources.

In this section, you will configure a Webhook URL on your forked Git repositories vote-ui and vote-api. This URL points to the publicly accessible EventListener service route.

Adding Webhooks requires administrative privileges to the repository. If you do not have administrative access to your repository, contact your system administrator for adding Webhooks.

Procedure
  1. Get the Webhook URL:

    $ echo "URL: $(oc  get route el-vote-app --template='http://{{.spec.host}}')"

    Note the URL obtained in the output.

  2. Configure Webhooks manually on the front-end repository:

    1. Open the front-end Git repository vote-ui in your browser.

    2. Click SettingsWebhooksAdd Webhook

    3. On the Webhooks/Add Webhook page:

      1. Enter the Webhook URL from step 1 in Payload URL field

      2. Select application/json for the Content type

      3. Specify the secret in the Secret field

      4. Ensure that the Just the push event is selected

      5. Select Active

      6. Click Add Webhook

  3. Repeat step 2 for the back-end repository vote-api.

Triggering a PipelineRun

Whenever a push event occurs in the Git repository, the configured Webhook sends an event payload to the publicly exposed EventListener service route. The EventListener service of the application processes the payload, and passes it to the relevant TriggerBindings and TriggerTemplates pair. The TriggerBinding extracts the parameters and the TriggerTemplate uses these parameters to create resources. This may rebuild and redeploy the application.

In this section, you push an empty commit to the front-end vote-ui repository, which then triggers the PipelineRun.

Procedure
  1. From the terminal, clone your forked Git repository vote-ui:

    $ git clone git@github.com:<your GitHub ID>/vote-ui.git -b release-tech-preview-2
  2. Push an empty commit:

    $ git commit -m "empty-commit" --allow-empty && git push origin release-tech-preview-2
  3. Check if the PipelineRun was triggered:

    $ tkn pipelinerun list

    Notice that a new PipelineRun was initiated.

Additional resources