Launching all pods on single node in Matrix task

[vinaykeenable]

Expected Behavior

Pod should be distributed on multiple nodes and should completed in few seconds.

Actual Behavior

I have list of values which I have configured with Matrix to run all in parallel. All pods are launching parallerly but Pod are launching on single node which is impacting to other pods which are hosted in same node.

Steps to Reproduce the Problem

Use mentioned task and try to reproduce

> apiVersion: tekton.dev/v1beta1
kind: Task
metadata:
  name: flyway
spec:
  params:
    - name: db
      type: string
  steps:
    - name: flyway
      image: flyway:v1
      onError: continue
      command: ["/bin/sh"]
      args:
        - -c
        - |  
          echo "print ${params.db}"
  workspaces:
    - name: space
---
apiVersion: tekton.dev/v1beta1
kind: Pipeline
metadata:
  name: Flyway-Pipeline
spec:
  workspaces:
    - name: space
    - name: ssh-creds
  tasks:
  - name: fetchfw
    taskRef:
      name: git-clone
    workspaces:
    - name: output
      workspace: space
    - name: basic-auth
      workspace: ssh-creds
    params:
    - name: url
      value: https://github.com/sql.git
    - name: deleteExisting
      value: false
    - name: revision
      value: master
  - name: arr0
    taskRef:
      name: flyway
    runAfter:
      - fetchfw
    workspaces:
    - name: space
      workspace: space
    matrix:
      params:
        - name: db
          value: ["abc","bcd","as","df","ds","ds","uy","re","ew","we","te","od","wer"]

Additional Info

• Kubernetes version:

  Output of kubectl version:

(paste your output here)

• Tekton Pipeline version:

  Output of tkn version or kubectl get pods -n tekton-pipelines -l app=tekton-pipelines-controller -o=jsonpath='{.items[0].metadata.labels.version}'

(paste your output here)

[AlanGreene]

This is expected and is the default behaviour of the affinity assistant. It provides node affinity for TaskRun pods that share a workspace volume.

This behaviour can be modified / disabled, see the docs on the affinity assistant