README.md

Developer docs

This document is aimed at helping maintainers/developers of project understand the complexity.

How are resources shared between tasks?

PipelineRun uses PVC to share resources between tasks. PVC volume is mounted on path /pvc by PipelineRun.

• If a resource in a task is declared as output then the TaskRun controller adds a step to copy each output resource to the directory path /pvc/task_name/resource_name.

• If an input resource includes from condition then the TaskRun controller adds a step to copy from PVC to directory path /pvc/previous_task/resource_name.

How are inputs handled?

Input resources, like source code (git) or artifacts, are dumped at path /workspace/task_resource_name. Resource definition in task can have custom target directory. If targetPath is mentioned in task input then the controllers are responsible for adding container definitions to create directories and also to fetch the versioned artifacts into that directory.

How are outputs handled?

Output resources, like source code (git) or artifacts (storage resource), are expected in directory path /workspace/output/resource_name.

• If resource has an output "action" like upload to blob storage, then the container step is added for this action.

• If there is PVC volume present (TaskRun holds owner reference to PipelineRun) then copy step is added as well.

• If the resource is declared only in output but not in input for task then the copy step includes resource being copied to PVC to path /pvc/task_name/resource_name from /workspace/output/resource_name like the following example.

  kind: Task
  metadata:
    name: get-gcs-task
    namespace: default
  spec:
    outputs:
      resources:
        - name: gcs-workspace
          type: storage

• If the resource is declared both in input and output for task the then copy step includes resource being copied to PVC to path /pvc/task_name/resource_name from /workspace/random-space/ if input resource has custom target directory (random-space) declared like the following example.

  kind: Task
  metadata:
    name: get-gcs-task
    namespace: default
  spec:
    inputs:
      resources:
        - name: gcs-workspace
          type: storage
          targetPath: random-space
    outputs:
      resources:
        - name: gcs-workspace
          type: storage

  • If resource is declared both in input and output for task without custom target directory then copy step includes resource being copied to PVC to path /pvc/task_name/resource_name from /workspace/random-space/ like the following example.

  kind: Task
  metadata:
    name: get-gcs-task
    namespace: default
  spec:
    inputs:
      resources:
        - name: gcs-workspace
          type: storage
    outputs:
      resources:
        - name: gcs-workspace
          type: storage