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Conditional Expression

Conditional expression allows a task or step that only runs if the condition is met. It can be defined on a task or on a step.

Conditional task

A conditional task consists of steps with a key when. The purpose of the when steps is customizing commands and job configuration to run on custom conditions (determined at compile time) that are checked before a workflow runs.

tasks:
    build-image:
      steps:
        ...
      when: branch == 'master'

Conditional step

A conditional step consists a step with a key if. The step will only run if the expression evaluates to true.

tasks:
    build-image:
      steps:
      - run: sudo apt-get update 
      ...
      - docker/build:
          image: example.com/demo
        if: branch == 'master'

The expression has access to the workflow related context objects branch, tag, platform and event. It can contain following tokens -

  • branch - refers to the git branch
  • tag - refers to the git tag if present
  • event - refer to the trigger event. Should be one of push, pull_request and tag.
  • platform - refers to the target operating system and architecture. for example linux/amd64. Refer $GOOS and $GOARCH for the possible values here.

You can provide more complex expression using operators and modifiers

branch == 'master'
branch in ('master', 'staging') || branch =~ 'hotfix' || tag
event == 'deployment'
platform == 'linux/amd64'