Implement simple PipelineRun

[bobcatfish]

Expected Behavior

A user should be able to create a PipelineRun which will look at the Tasks in the referenced Pipeline and for each of those, create a TaskRun.

If #59 is done before this, creation of the TaskRun would also trigger running of the Task, however if not, nothing would actually be executed but the TaskRuns would exist.

Out of scope of this issue (coming in later issues):

• Providing inputs to the Tasks
• Doing something with produced outputs

Requirements:

• Test coverage (unit tests + if possible integration tests, may be blocked by Setup PR testing for build-pipeline integration tests #16 )
• Docs that explain how to create a PipelineRun, with examples
• Docs that explain how to debug this (i.e. where to look if it goes wrong)

Actual Behavior

If you create a PipelineRun, nothing will happen.

Steps to Reproduce the Problem

1. Deploy the Pipeline CRD + related CRDs to your cluster (note: should be docs on how to do this post kubebuilder)
2. Create a Task like this:

apiVersion: pipeline.knative.dev/v1beta1
kind: Task
metadata:
  name: helloworld-task
  namespace: default
spec:
    buildSpec:
        steps:
            - name: helloworld
              image: busybox
              args: ['echo', 'hello', 'build']

3. Create a Pipeline like this:

apiVersion: pipeline.knative.dev/v1beta1
kind: Pipeline
metadata:
  name: hello-pipeline
  namespace: default
spec:
    tasks:
        - name: helloworld-task-1
          taskRef:
              name: helloworld-task
        - name: helloworld-task-2
          taskRef:
              name: helloworld-task
        - name: helloworld-task-3
          taskRef:
              name: helloworld-task

4. Create a PipelineRun like this:

apiVersion: pipeline.knative.dev/v1beta1
kind: PipelineRun
metadata:
  name: hello-pipeline-run-1
  namespace: default
spec:
    pipelineRef:
        name: hello-pipeline
    triggerRef:
        type: manual

5. Creating the PipelineRun should have created TaskRuns, so we should then be able to see:

a. The status of the PipelineRun should be updated (see example), check with kubectl get pipelineRuns
b. There should be 3 TaskRuns created, each with a unique name and a reference to the PipelineRun (check with kubectl get taskRuns), for example:

apiVersion: pipeline.knative.dev/v1beta1
kind: TaskRun
metadata:
  name: helloworld-task-run-1-1
spec:
    taskRef:
        name: helloworldTask
    trigger:
        triggerRef:
            type: manual

(I left the PipelineParams reference out of the PipelineRun, but if it turns out that we need a ServiceAccount to make this work, we'll need to specify it in the PipelineParams and reference it in the PipelineRun as well)

[tejal29]

@bobcatfish Was looking at if there is a way to divide this further.
Few subtasks i am thinking of:

• Add unit tests for task_controller.go
• Add unit tests for task_run_controller.go

On the branch, i went ahead and added all the methods

• runWorker
• processNextWorkItem
• enqueueBuild
• syncHandler
  etc..

We could potentially see if
https://github.com/knative/build-pipeline/blob/master/pkg/controller/taskrun/controller.go#L275 has some tasks recorded.
We can pair on adding these tests in pipeline controller and then add them in the other controllers.