GitHub Actions Workflow Syntax: ‘if’ – Conditional Execution of Steps

GitHub Actions provides a powerful platform for automating tasks in the software development lifecycle. This blog post is focused on the ‘if’ keyword in the GitHub Actions Workflow syntax. This feature enables conditional execution of steps, providing a flexible way to control when and under what conditions steps are executed in a workflow. We will discuss its syntax, usage, and illustrate with practical examples.

Introduction

GitHub Actions Workflows provide automation of tasks like building, testing, and deploying applications. These workflows consist of ‘jobs’, each containing ‘steps’ that execute tasks. One feature that adds flexibility to this structure is the ability to control the execution of steps using the ‘if’ keyword.

Understanding the ‘if’ Syntax for Steps

The ‘if’ keyword in GitHub Actions Workflow syntax allows you to set a condition that controls whether a step is executed or not. If the condition is satisfied, the step is executed. If not, the step is skipped.

Here’s a basic structure of defining a condition for a step:

jobs:
  job_id:
    runs-on: runner_type
    steps:
    - name: Conditional Step
      run: command
      if: condition

jobs:

job_id:

runs-on: runner_type

steps:

- name: Conditional Step

run: command

if: condition

In the above syntax, ‘condition’ is an expression that evaluates to ‘true’ or ‘false’. The ‘if’ statement supports context and expressions.

Example of ‘if’ in a Workflow

Let’s consider an example where a GitHub Actions Workflow uses ‘if’ to conditionally execute steps based on the branch name.

name: Conditional Execution Workflow

on: [push]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - name: Checkout code
      uses: actions/checkout@v2
    - name: Run tests
      run: npm test
    - name: Deploy
      run: npm run deploy
      if: github.ref == 'refs/heads/main'

name: Conditional Execution Workflow

on: [push]

jobs:

build:

runs-on: ubuntu-latest

steps:

- name: Checkout code

uses: actions/checkout@v2

- name: Run tests

run: npm test

- name: Deploy

run: npm run deploy

if: github.ref == 'refs/heads/main'

In this workflow, the ‘build’ job has three steps. The first two steps checkout the code and run tests, respectively. The third step, ‘Deploy’, is conditionally executed only if the event triggering the workflow is a push to the ‘main’ branch. The condition for the ‘if’ statement uses the ‘github’ context to check the branch name.

Conclusion

The ‘if’ keyword in GitHub Actions Workflow syntax adds significant flexibility and control over when and how steps within a job are executed. By using ‘if’ to conditionally control step execution, developers can create more dynamic and efficient workflows.