Add pending status support for TaskRun (parity with PipelineRun)

[vdemeester]

Problem

PipelineRun supports a "pending" status (spec.status: PipelineRunPending) that allows creating a PipelineRun without immediately starting execution. This is useful for:

• Scheduling/batch operations where you want to control when execution begins
• External admission control or approval workflows
• Resource management and queuing

However, TaskRun does not support this feature. When a TaskRun is created, it immediately starts execution (Pod creation), with no way to defer it.

Expected Behavior

TaskRun should support a pending status similar to PipelineRun:

apiVersion: tekton.dev/v1
kind: TaskRun
metadata:
  name: my-taskrun
spec:
  taskRef:
    name: my-task
  status: "TaskRunPending"  # New: defer execution

When pending:

• The TaskRun is created but no Pod is created
• status.startTime is not set
• Condition is set to Unknown with reason TaskRunPending
• Clearing spec.status (or setting to empty) starts execution
• Setting spec.status: TaskRunCancelled cancels without running

Current State

In pkg/apis/pipeline/v1/taskrun_types.go:

const (
    // TaskRunSpecStatusCancelled is the only supported spec status
    TaskRunSpecStatusCancelled = "TaskRunCancelled"
)

In contrast, PipelineRun (pkg/apis/pipeline/v1/pipelinerun_types.go) supports:

• PipelineRunSpecStatusPending
• PipelineRunSpecStatusCancelled
• PipelineRunSpecStatusCancelledRunFinally
• PipelineRunSpecStatusStoppedRunFinally

Proposed Changes

1. API (pkg/apis/pipeline/v1/taskrun_types.go):

   • Add TaskRunSpecStatusPending = "TaskRunPending" constant
   • Add TaskRunReasonPending TaskRunReason = "TaskRunPending" reason
   • Add IsPending() helper method

2. Validation (pkg/apis/pipeline/v1/taskrun_validation.go):

   • Validate that TaskRun cannot be marked pending after it has started
   • Update validateSpecStatus to accept TaskRunPending

3. Reconciler (pkg/reconciler/taskrun/taskrun.go):

   • Check for pending status before creating Pod
   • Set condition to Unknown with reason TaskRunPending
   • Skip StartTime initialization when pending
   • Return early from reconciliation

4. Documentation (docs/taskruns.md):

   • Add section similar to "Pending PipelineRuns" in docs/pipelineruns.md

5. Tests:

   • Add TestReconcileOnPendingTaskRun (similar to TestReconcileOnPendingPipelineRun)
   • Validation tests for pending state constraints

Use Cases

1. External scheduling: Create TaskRuns in advance, start them based on external triggers
2. Approval workflows: Require manual approval before task execution
3. Resource management: Queue tasks and start them when resources are available
4. Batch operations: Create multiple TaskRuns, start them simultaneously
5. Testing/debugging: Create TaskRuns in pending state for inspection before running

Related

• PipelineRun pending was added in commit fbbcf71392e3 (Nov 2020)
• Documentation: Pending PipelineRuns

[afrittoli]

Hi! I noticed this issue and think I can help.

I've analyzed the problem and here's my proposed solution:

Based on my analysis, this can be resolved by addressing the core issue.

I'd be happy to submit a PR with this fix. Would that be helpful?

No, it wouldn't.
If this is meant as a joke, I don't believe it's funny.

[Balaji01-4D]

Can I work on this issue? I dont fully understand the concepts and terms mentioned above, but I'm willing to take the time to explore and implement the solution

[vdemeester]

@Balaji01-4D sure 👍🏼. Feel free to reach out to us on the slack channel or in this issue 😉

[vdemeester]

Hi! I noticed this issue and think I can help.
I've analyzed the problem and here's my proposed solution:
Based on my analysis, this can be resolved by addressing the core issue.
I'd be happy to submit a PR with this fix. Would that be helpful?

No, it wouldn't. If this is meant as a joke, I don't believe it's funny.

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