Create Pipeline

A pipeline defines a number of tasks that should be executed and how they interact with each other via their inputs and outputs.

In this tutorial, you will create a pipeline that takes the source code of the application from GitHub and then builds and deploys it on OpenShift.

Pipeline Diagram

Here is the YAML file that represents the above pipeline:

apiVersion: tekton.dev/v1beta1
kind: Pipeline
metadata:
  name: build-and-deploy
spec:
  resources:
  - name: git-repo
    type: git
  - name: image
    type: image
  params:
  - name: deployment-name
    type: string
    description: name of the deployment to be patched
  tasks:
  - name: build-image
    taskRef:
      name: buildah
      kind: ClusterTask
    resources:
      inputs:
      - name: source
        resource: git-repo
      outputs:
      - name: image
        resource: image
    params:
    - name: TLSVERIFY
      value: "false"
  - name: apply-manifests
    taskRef:
      name: apply-manifests
    resources:
      inputs:
      - name: source
        resource: git-repo
    runAfter:
    - build-image
  - name: update-deployment
    taskRef:
      name: update-deployment
    resources:
      inputs:
      - name: image
        resource: image
    params:
    - name: deployment
      value: $(params.deployment-name)
    runAfter:
    - apply-manifests

Once you deploy the pipelines, you should be able to visualize pipeline flow in the OpenShift Web Console by switching over to the Developer perspective of the OpenShift Web Console. select pipeline tab, select project as pipelines-tutorial and click on pipeline build-and-deploy

Pipeline-view

This pipeline helps you to build and deploy backend/frontend, by configuring the right resources to pipeline.

Backend:

1. Clones the source code of the backend application from a git repository when (git-repo git resource) refered to api-repo

2. Builds the container image of backend using the buildah clustertask that uses Buildah to build the image

3. The application image is pushed to an image registry by referring (image image resource) to api-image

4. The new backend application image is deployed on OpenShift using the apply-manifests and update-deployment tasks.

Frontend:

1. Clones the source code of the backend application from a git repository when (git-repo git resource) referred to ui-repo

2. Builds the container image of backend using the buildah clustertask that uses Buildah to build the image

3. The application image is pushed to an image registry by referring (image image resource) to ui-image

4. The new backend application image is deployed on OpenShift using the apply-manifests and update-deployment tasks.

You might have noticed that there are no references to the git repository or the image registry it will be pushed to in pipeline. That's because pipeline in Tekton is designed to be generic and re-usable across environments and stages through the application's lifecycle. Pipelines abstract away the specifics of the git source repository and image to be produced as PipelineResources. When triggering a pipeline, you can provide different git repositories and image registries to be used during pipeline execution. Be patient! You will do that in a little bit in the next section.

The execution order of task is determined by dependencies that are defined between the tasks via inputs and outputs as well as explicit orders that are defined via runAfter.

Create the pipeline by running the following:

oc create -f https://raw.githubusercontent.com/openshift/pipelines-tutorial/master/01_pipeline/04_pipeline.yaml

Alternatively, in the OpenShift Web Console, you can click on the + at the top right of the screen while you are in the pipelines-tutorial project:

OpenShift Console - Import Yaml

Upon creating the pipeline via the web console, you will be taken to a Pipeline Details page that gives an overview of the pipeline you created.

Check the list of pipelines you have created using the CLI:

tkn pipeline ls

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