TEP-0158: pipeline fail fast

Signed-off-by: chengjoey <zchengjoey@gmail.com>

Author: chengjoey

teps/0158-pipeline-fail-fast.md

@@ -0,0 +1,160 @@
+---
+status: implementable
+title: Pipeline fail-fast
+creation-date: '2024-08-17'
+last-updated: '2024-08-17'
+authors:
+- '@chengjoey'
+---
+
+# TEP-0158: Pipeline fail-fast
+
+<!-- toc -->
+- [Summary](#summary)
+- [Motivation](#motivation)
+  * [Goals](#goals)
+  * [use-cases](#use-cases)
+- [Proposal](#proposal)
+    * [failFast](#failfast)
+    * [config-defaults](#config-defaults)
+    * [PipelineRun](#pipelinerun)
+    * [Pipeline](#pipeline)
+- [Design Evaluation](#design-evaluation)
+    * [Priority](#priority)
+    * [Performance](#performance)
+- [References](#references)
+<!-- /toc -->
+
+
+## Summary
+
+This proposal is to support stopping the execution of the Pipeline immediately when a Task in the Pipeline failed.
+Because there may be multiple parallel tasks in the pipeline, when one task fails,
+The final status of the pipeline is Failed, but other tasks may still be executed,
+which will waste resources. Therefore, we need a mechanism to support the
+immediate stop of pipeline execution when a task failed.
+
+## Motivation
+
+When a Task in a Pipeline fails, the Pipeline status may eventually change to Failed, but other parallel Tasks continue to execute. 
+When the final Pipeline status is Failed, There is a high probability that users will create a new Pipeline execution,
+because in many cases they hope that the final Pipeline status will be Success. Therefore, 
+in this case, it is necessary to stop the Pipeline execution as soon as possible. The fail-fast mechanism can 
+reduce the waste of resources on the one hand, and on the other hand, 
+it can also let users know the execution results of the Pipeline as soon as possible.
+
+### Goals
+
+- Support canceling the execution of the Pipeline immediately when a Task in the Pipeline failed.
+
+### use-cases
+
+Take the following pipeline as an example. When `fail-task` fails to execute, 
+the parallel `success1` and `success2`Tasks will exit execution.
+The status of PipelineRun is `Failed`, the status of `fail-task` is `Failed`, 
+and the status of `success1` and `success2` are `RunCancelled`.
+
+```yaml
+apiVersion: tekton.dev/v1
+kind: PipelineRun
+metadata:
+  name: pipeline-run
+spec:
+  failFast: "true"
+  pipelineSpec:
+    tasks:
+    - name: fail-task
+      taskSpec:
+        steps:
+          - name: fail-task
+            image: busybox
+            command: ["/bin/sh", "-c"]
+            args:
+              - exit 1
+    - name: success1
+      taskSpec:
+        steps:
+          - name: success1
+            image: busybox
+            command: ["/bin/sh", "-c"]
+            args:
+              - sleep 360
+    - name: success2
+      taskSpec:
+        steps:
+          - name: success2
+            image: busybox
+            command: ["/bin/sh", "-c"]
+            args:
+              - sleep 360
+```
+
+## Proposal
+
+### failFast
+
+The `failFast` property is of string type and supports the following values:
+1. `true`: When a Task in the Pipeline fails, the Pipeline execution is stopped immediately.
+2. `false`: This is consistent with the current behavior. When a Task in a Pipeline fails, the Pipeline status changes to Failed, but other Tasks continue to execute.
+
+### config-defaults
+
+Add the `default-fail-fast` field in `config-defaults` to set the default fail-fast attribute for all Pipelines.
+
+```yaml
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: config-defaults
+  namespace: tekton-pipelines
+data:
+  # Default fail-fast attribute for all Pipelines
+  default-fail-fast: "true"
+```
+
+### PipelineRun
+
+Add the `failFast` field in PipelineRun to set the fail-fast property of the PipelineRun at runtime.
+
+```yaml
+apiVersion: tekton.dev/v1
+kind: PipelineRun
+metadata:
+  name: pipeline-run
+spec:
+  failFast: "true"
+  pipelineSpec:
+  ...
+```
+
+### Pipeline
+
+Add the `failFast` field in Pipeline to set the fail-fast property of Pipeline.
+
+```yaml
+apiVersion: tekton.dev/v1
+kind: Pipeline
+metadata:
+  name: "demo.pipeline"
+spec:
+    failFast: "true"
+    tasks:
+    ...
+```
+
+## Design Evaluation
+
+### Priority
+
+The `failFast` priority is：PipelineRun > Pipeline > config-defaults
+
+### Performance
+
+PipelineRun status is `Failed`, failed Task status is `Failed`, and other parallel Task status is `RunCancelled`.
+When a Task fails, the Cancel event is triggered to cancel the execution of PipelineRun.
+
+## References
+
+* Implementation Pull Requests:
+    * [Tekton Pipelines PR #7987 - support fail-fast for PipelineRun][pr-7987]
+* [Tekton Pipelines Issue #7880][issue-7880]