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GitHub Actions

Platform to automate Developer Workflows. CI/CD pipelines is just one of the many workflows that GitHub Actions can be used for. - Any GitHub event that occurs can trigger a workflow which is an automated execution of tasks = GitHub Action

CI&CD Pipelines

  1. commit code
  2. test code
  3. build code
  4. push artifact
  5. deploy artifact on server

GitHub Action CI/CD Example

  • GitHub Actions already has a bunch of workflow templates for applications. 3 types of workflows: Deployment, continious integration build and test, and continious integration publish workflows

  • If you go to Actions on your repo and then select a workflow as a template than it will automatically create the following:

  • .github/workflows: Creates the folder that holds the Action workflow
  • *.yml: The yaml file that contains the instuctions

Workflow Syntax

Main Parameters include: 

   - `name`: This is just the name of the Action
   - `on`: This is the section that describes the event you can also do multiple events like *on and pull request*
        `push`: 
            `branches`: [Master]

    - `jobs`: A set of actions that get executed 

        -  `runs-on`: ubuntu-latest

        - `steps`: 
           - `uses`: actions/checkout@v2 - This is a predefined action that handles your repo checkout that was made my GitHub. If you go to github.com/actions you can see the full list of pre-defined actions 

           - name: Set up JDK 1.8
                uses: actions/setup-java@v1
                with:
                    java-version: 1.8

             - name: Grant execute permission for gradlew
                run: chmod +x gradlew    #Whenver we use an action we use the *uses* keyword but when we need to run a specific command use *run*
- When you push to master or make a PR to master that above action will automatically start

- The code is run on GitHub servers which means you do not have to manage them. Each new job runs on a new virtual enviornment. In the above example, we only put one job but you can put multiple jobs and they will all run on different virtual machines.
   - **By default the jobs run in parallel but you can overwrite this by using the keyword needs under the second jobs like `needs: firstjob`**

- The runs on command determines what OS to run the build on (ubuntu, macOS, or Windows). Using the `matrix` keyword is needed when you want to test on multiple OS then you switch the runs-on to use {{matrix.os}}

Build a Docker Image from the Artifact Generated

  • You define this also within the workflow action as another step

    - name: Build and push Docker Image
        run: You can put all of the commands required to build and then bush the docker image and if you need multiple commands then you use the pipe syntax. ie. |
        docker login cred
        docker build
            - On Ubuntu machines docker is already pre-installed so you don't have to setup docker to use the commands
            - but instead of using the run command there is an action for the docker build and push and these are found in the *GitHub Actions Marketplace*
- For credentials you can store them in GitHub as secrets