GitHub Actions

Description

Learning to use Github Actions feels like a valueable skill to build. This repository automatically commits updates to a markdown file.

Link to the GitHub Repository

Running the Program

This program is run automatically by GitHub Actions based on the cron schedule defined in the workflow YAML file.

Adding a Workflow

Within your repository, create a directory structure for `.github/workflows` and create a `.yml` file with a name describing the scripts purpose. See my workflow for an example but lets quickly cover a few aspects of this file.

Triggering the Workflow

The workflow is triggered by a `schedule` using a `cron` expression. The workflow contains a single job named commit, which executes on a standard ubuntu-latest runner.

on:
  schedule:
    - cron: '0 */8 * * *'

Checkout the Repository

The first step uses the standard `actions/checkout@v2` action to prepare the runner environment. This essential process downloads a copy of the repository's code from GitHub onto the virtual machine running the job. By specifying `ref: main`, the workflow ensures it is working on the latest code from the `main` branch, allowing it to read existing files and make new changes.

    - name: Checkout repository
      uses: actions/checkout@v2
      with:
        ref: main

Creating and Updating a File

This step executes a Bash script to manage the `test_actions.md` file and push the updated count. The script first checks if the file exists; if it doesn't, it's created with an initial rolling count of 1. If the file is found, the script uses `grep` to extract the current rolling count, increments that number by one, and uses `sed` to update the file with the new count. Finally, it configures Git user credentials, stages the modified file, creates a new commit with the message "Incremental test of Github Actions", and pushes the change back to the repository using the secured `GITHUB_TOKEN` for authentication.

    - name: Create file and update
      run: |
        FILE="test_actions.md"
        if [ ! -f "$FILE" ]; then
          echo "Below is a Rolling Count to test Github Actions:
" > "$FILE"
          echo "Rolling Count: 1" >> "$FILE"
        else
          CURRENT_COUNT=$(grep -oP 'Rolling Count: \K\d+' "$FILE")
          if [ -z "$CURRENT_COUNT" ]; then
            CURRENT_COUNT=0
          fi
          NEXT_COUNT=$((CURRENT_COUNT + 1))
          sed -i "/Rolling Count: /c\Rolling Count: $NEXT_COUNT" "$FILE"
        fi
        git config --global user.name "CodingAero"
        git config --global user.email "smithaero12@gmail.com"
        git add "$FILE"
        git commit -m "Incremental test of Github Actions"
        git push https://x-access-token:${{ secrets.GITHUB_TOKEN }}@github.com/CodingAero/GithubActions.git
      env:
        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

Permissions

Github Actions will need permission to commit to your repository. This can be configured in `Settings` > `Actions` > `General`. Under `Workflow permissions`, check the read and write permissions option.