#Result Limit Exceeded When Writing Tekton Task Results

#Problem Description

When a Task step writes relatively large content into a Task result, the output may fail due to size limits.

#Error Manifestation

• Pod logs show termination message overflow (result too large for default 4 KB cap):

  2025/10/15 03:22:24 ERROR Error while substituting step artifacts: error="Termination message is above max allowed size 4096, caused by large task result."
  2025/10/15 03:22:24 Termination message is above max allowed size 4096, caused by large task result.

#Root Cause Analysis

By default, Tekton Pipelines captures Task results through the container termination message, which Kubernetes limits to 4 KB. This effectively caps a single Task's usable result size to 4096 bytes.

To lift that ceiling, Tekton supports reading results from sidecar logs, where a configurable max-result-size is applied per result.

#Troubleshooting

Following are the steps to configure the result size limit:

1. Edit the TektonConfig resource by setting spec.pipeline.results-from and spec.pipeline.max-result-size as shown below:

   apiVersion: operator.tekton.dev/v1alpha1
   kind: TektonConfig
   metadata:
     name: config
   spec:
     pipeline:
       # Use sidecar logs instead of termination messages
       results-from: sidecar-logs
       # Result size in bytes (example: 64 KiB). Max is 1,572,863 bytes.
       max-result-size: 65536

2. The feature-flags ConfigMap will be updated automatically.

   apiVersion: v1
   kind: ConfigMap
   metadata:
     name: feature-flags
     namespace: tekton-pipelines
   data:
     results-from: sidecar-logs
     max-result-size: "65536"

3. Since the results-from: sidecar-logs feature is enabled, you need to configure log access permissions for the controller:

   Technical Note: This configuration allows the controller to retrieve results information from pod logs. For detailed information, please refer to the Tekton official documentation.

   kubectl apply -f - <<EOF
   kind: ClusterRole
   apiVersion: rbac.authorization.k8s.io/v1
   metadata:
     name: tekton-pipelines-controller-pod-log-access
     labels:
       app.kubernetes.io/component: controller
       app.kubernetes.io/instance: default
       app.kubernetes.io/part-of: tekton-pipelines
   rules:
     - apiGroups: [""]
       resources: ["pods/log"]
       verbs: ["get"]
   ---
   kind: ClusterRoleBinding
   apiVersion: rbac.authorization.k8s.io/v1
   metadata:
     name: tekton-pipelines-controller-pod-log-access
     labels:
       app.kubernetes.io/component: controller
       app.kubernetes.io/instance: default
       app.kubernetes.io/part-of: tekton-pipelines
   subjects:
     - kind: ServiceAccount
       name: tekton-pipelines-controller
       namespace: tekton-pipelines
   roleRef:
     kind: ClusterRole
     name: tekton-pipelines-controller-pod-log-access
     apiGroup: rbac.authorization.k8s.io
   EOF

4. No manual component restarts are required, changes will take effect automatically.

#Related Content

• TektonPipeline
• TektonConfig