GitHub Actions: Action Inputs and Outputs

1. Introduction

GitHub Actions allows developers to automate workflows for their projects. Understanding action inputs and outputs is crucial for creating reusable and dynamic actions.

2. Action Inputs

Inputs are parameters that are passed to an action. They allow users to customize the action's behavior.

2.1 Defining Inputs

Inputs are defined in the action’s metadata file, usually action.yml.

inputs:
  my_input:
    description: 'This is a sample input'
    required: true
    default: 'default_value'

2.2 Accessing Inputs

Inside your action, you can access inputs using the github.action context.

echo "Input value: ${{ inputs.my_input }}"

3. Action Outputs

Outputs are values that an action can return, which can be used by subsequent actions in a workflow.

3.1 Defining Outputs

Outputs are also defined in the action’s metadata file.

outputs:
  my_output:
    description: 'This is a sample output'

3.2 Setting Outputs

You can set outputs in your action code. For example, in a shell script:

echo "::set-output name=my_output::Hello, World!"

4. Best Practices

• Always validate inputs to ensure they meet expected formats.
• Clearly document inputs and outputs in the action metadata file.
• Use default values wisely to enhance usability.
• Test actions in isolation to ensure they handle inputs and outputs correctly.

5. FAQ