tekton-pipeline-to-test-and-deploy.yaml

#                   unit-test
#                      |
#                  integration-test
#                    /    \
#              cleanup   deploy
#                          |
#                       rollback

# 1. test-pipeline:
# unit-test
#    |
# integration-test
#    |finally
# cleanup

apiVersion: tekton.dev/v1beta1
kind: Pipeline
metadata:
  name: test-pipeline
spec:
  tasks:
    - name: unit-test
      taskRef:
        Name: unit-test
    - name: integration-tests
      taskRef:
        Name: integration-tests
      runAfter: unit-test
  finally:
    - name: cleanup
      taskRef:
        Name: cleanup
---

# 2. deploy-pipeline:
# deploy
#    |onFailure/except
# rollback

# Pipeline Level Except (thanks Christie for clarifying 🙏)
# Pros: (1) fits perfect with programming paradigm of try and except
#       (2) works with task level mappings (params and workspace), unlike conditions e.g. https://gist.github.com/pritidesai/d016fd7fa32709970f8c78ecf64e484e
# Cons: (2) failure from any task under `tasks` trigger `except` 🤔

apiVersion: tekton.dev/v1beta1
kind: Pipeline
metadata:
  name: deploy-pipeline
spec:
  tasks:
    - name: deploy
      taskRef:
        Name: deploy
  except:
    - name: rollback
      taskRef:
        Name: rollback
---

OR

# Task level except
# Pros: fits perfect with programming paradigm of try and except
# Cons: (1) params and workspace mapping in `PipelineRun`
#       (2) maintainance nightmare, patch/enhance `except` just like conditions 🤔

apiVersion: tekton.dev/v1beta1
kind: Pipeline
metadata:
  name: deploy-pipeline
spec:
  tasks:
    - name: deploy
      taskRef:
        Name: deploy
      except: # OR except Failure: OR exceptFailure: (???)
        - name: rollback # - exceptRef just like conditionRef (???)
          taskRef:
            Name: rollback
---

# Pros: (1) Minimal changes to existing spec
#       (2) task and pipeline both supported with nested pipeline
# Cons: ???

OR

apiVersion: tekton.dev/v1beta1
kind: Pipeline
metadata:
  name: deploy-pipeline
spec:
  tasks:
    - name: deploy
      taskRef:
        Name: deploy
    - name: rollback
      taskRef:
        Name: rollback
      runOnFailure: deploy
---

# 3. entire-pipeline with sub-pipelines:
# test-pipeline
#     |
# deploy-pipeline
apiVersion: tekton.dev/v1beta1
kind: Pipeline
metadata:
  name: deploy-pipeline
spec:
  tasks:
    - name: test
      pipelineRef:
        Name: test-pipeline
    - name: deploy
      pipelineRef:
        Name: deploy-pipeline
      runAfter: test