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History-based Pruning

Retain a fixed number of runs based on their status, regardless of age.

How It Works

History limits work independently from TTL. When a new run completes and the count exceeds the limit, the oldest runs are deleted. Always keeps the N most recent runs of each status.

Configuration Options

Setting Description
successfulHistoryLimit Keep N most recent successful runs
failedHistoryLimit Keep N most recent failed runs
historyLimit Keep N runs of EACH status (when specific limits not set)

Basic Configuration

Separate limits by status:

apiVersion: v1
kind: ConfigMap
metadata:
  name: tekton-pruner-default-spec
  namespace: tekton-pipelines
  labels:
    app.kubernetes.io/part-of: tekton-pruner
    pruner.tekton.dev/config-type: global
data:
  global-config: |
    successfulHistoryLimit: 5    # Keep last 5 successful
    failedHistoryLimit: 10       # Keep last 10 failed (for debugging)

Same limit for both:

data:
  global-config: |
    historyLimit: 5  # Keep last 5 successful AND last 5 failed

Environment-specific Limits

data:
  global-config: |
    enforcedConfigLevel: namespace
    namespaces:
      dev:
        successfulHistoryLimit: 3
        failedHistoryLimit: 5     # More failed runs for debugging
      staging:
        successfulHistoryLimit: 5
        failedHistoryLimit: 5
      prod:
        successfulHistoryLimit: 10
        failedHistoryLimit: 20

Pipeline-specific Limits

Use selectors in namespace ConfigMaps for pipeline-specific limits:

apiVersion: v1
kind: ConfigMap
metadata:
  name: tekton-pruner-namespace-spec
  namespace: my-app
  labels:
    app.kubernetes.io/part-of: tekton-pruner
    pruner.tekton.dev/config-type: namespace
data:
  ns-config: |
    successfulHistoryLimit: 3
    pipelineRuns:
      - selector:
        - matchLabels:
            critical: "true"
        successfulHistoryLimit: 20
        failedHistoryLimit: 30
      - selector:
        - matchLabels:
            pipeline-type: test
        successfulHistoryLimit: 3
        failedHistoryLimit: 5

Interaction with TTL

Important: Setting a history limit does NOT prevent TTL from deleting runs.

If you set both TTL and history limit, they run separately. TTL will still delete runs after the time passes, even if you're under the history limit.

data:
  ns-config: |
    ttlSecondsAfterFinished: 300
    successfulHistoryLimit: 5
    failedHistoryLimit: 10

Example: With the config above, if you only have 3 successful runs and 2 failed runs, and they're all older than 5 minutes, all 5 will be deleted by TTL.

If you want to keep N runs regardless of age, don't set a TTL - just use history limits alone.

Verification

# Check retained runs by status
kubectl get pr -l tekton.dev/pipeline=<name> --field-selector status.conditions[0].status=True
kubectl get pr -l tekton.dev/pipeline=<name> --field-selector status.conditions[0].status=False# Monitor pruning
kubectl logs -n tekton-pipelines -l app=tekton-pruner-controller | grep "history"

Best Practices

  1. Keep more failed runs than successful for debugging
  2. Critical pipelines: Higher limits for audit trails
  3. Development: Lower limits (3-5) for rapid iteration
  4. Production: Higher limits (10-20) for analysis
  5. Monitor storage: Adjust limits based on cluster capacity

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