Pipeline uses passedConstraints to provide correct inputs and outputs

[bobcatfish]

Expected Behavior

If a user creates a Pipeline which has passedConstraints specified, this should be used to construct a DAG of tasks (including fan in and fan out)
2. Ensure that the version of the Resource used by the task is the same as the version used by the Task(s) in the passedConstraint

Should include:

• Expanding the docs about how to use Resources that are changed between Tasks and how to use passedConstraints to make sure the right versions are used
• Test coverage, unit and also integration if possible (see Setup PR testing for build-pipeline integration tests #16)

Actual Behavior

After #61 we will have a simple Pipeline in which either the DAG is flat or all Tasks execute simultaneously; i.e. the passedConstraints are ignored.

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 Resource that brings in the hello-world docker image repo, and declares an image we will be building (gcr.io/my-registry must be changed to a registry that the specified serviceAccounts will have permission to push to):

apiVersion: pipeline.knative.dev/v1beta1
kind: Resource
metadata:
  name: resources
  namespace: default
spec:
  resources:
    - name: hello-world-resource
      type: github
      params:
      - name: url
        value: https://github.com/docker-library/hello-world
      - name: revision
        value: master
    - name: hello-world-image
      type: image
      params:
        - name: url
          value: gcr.io/my-registry

2. Create a two Tasks, the first will build an image (using Kaniko, see Implement working kaniko build Task #62), the second will run the image:

apiVersion: pipeline.knative.dev/v1beta1
kind: Task
metadata:
  name: build-push
  namespace: default
spec:
    inputs:
        resources:
        - name: workspace
          type: github
        params:
            - name: pathToDockerFile
              value: string
    outputs:
        resources:
        - name: imageToBuild
          type: image
    buildSpec:
      steps:
         - name: build-and-push
           image: gcr.io/kaniko-project/executor
      args:
         - --dockerfile=${DOCKERFILE}
         - --destination=${IMAGE}

apiVersion: pipeline.knative.dev/v1beta1
kind: Task
metadata:
  name: run
  namespace: default
spec:
    inputs:
        resources:
        - name: imageToRun
          type: image
    buildSpec:
      steps:
         - name: run-image
           image: "${imageToRun.url}/${imageToRun.name}"

3. Create a Pipeline which wires the two Tasks together using passedConstraints:

apiVersion: pipeline.knative.dev/v1beta1
kind: Pipeline
metadata:
  name: hello-world-pipeline
  namespace: default
spec:
    tasks:
        - name: build-hello-world
          taskRef:
              name: build-push
          inputSourceBindings:
          - key: workspace
            resourceRef:
                 name: hello-world-resource
          outputSourceBindings:
          - key: imageToBuild
             resourceRef:
                 name: hello-world-image
        - name: run-hello-world
          taskRef:
              name: run
          inputSourceBindings:
          - name: imageToRun
             resourceRef:
                 name: hello-world-image
             passedConstraints: ['build-hello-world']

4. Create a PipelineRun which invokes the Tasks (you'll have to create a PipelineParams as well with your serviceAccount, in this case called hello-world-params:

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

5. Creating the PipelineRun should have created TaskRuns with all of the values filled in, so with kubectl get taskRuns you should be able to see conditions updated appropriately

6. Looking at the Task logs (if this has been implemented, see Implement working "hello world" Task + TaskRun #59) or at the logs for the running pod if not, you should be able to see that the hello world image was run and output the expected value from the hello world image

7. You should be able to see hello-world image built and pushed to your registry.

Additional Info

• Blocked by Implement simple PipelineRun #61 (simple PipelineRun) and Implement working kaniko build Task #62 (build and push using Kaniko)

[bobcatfish]

Create a Pipeline which wires the two Tasks together using passedConstraints:

lol the passedConstraints - literally the most important part of this task - are missing from the example! 😅

[bobcatfish]

I think that between #168 (remove default linear execution) and #148 (link outputs and inputs) this issue will be taken care of, resolving as duplicate.