DevOps Classroom notes 13/Sep/2025

Github Actions

Github Expressions and Contexts

• Refer Here for github contexts
• Context is a way to access information inside an expression
• Contexts are like namespaces/objects that hold variables we can query
• Expression syntax

${{ context.property }}

Exploring Contexts

• Use the following github action in any repo and push the changes

---

on:
    push:
      branches:
        - main

jobs:
    context-job:
        runs-on: ubuntu-latest
        steps:
          - run: "echo Repo: ${{ github.repository }} by ${{  github.actor }}"
          - name: Show complete github context
            run: echo '${{  toJson(github) }}'
          - name: Show complete env context
            run: echo '${{  toJson(env) }}'
          - name: Show complete runner context
            run: echo '${{  toJson(runner) }}'

Variable types in Github

Environmental variables

• We can define variables at workflow, job or step level with env and they can be accessed using env context
• Execute the following

---

on:
    push:
      branches:
        - main
env:
    GLOBAL_ENV_VAR: learning thoughts global
    ORG_NAME: xyz limited

jobs:
    context-job:
        runs-on: ubuntu-latest
        env:
            JOB_ENV_VAR: learning thoughts job
            ORG_NAME: abc limited
        steps:
            - name: steps example
              env:
                STEP_VAR: learning thoughts step

              run: echo '${{ env.GLOBAL_ENV_VAR }}  ${{ env.JOB_ENV_VAR }}  ${{ env.STEP_VAR }}'
            - name: same environment
              env:
                ORG_NAME: 123 limited
              run: echo '${{ env.ORG_NAME }}'

Variables and Secrets

• Variables can be defined at org level or repo level
• Secrets can be defined at org level or repo level
• Secrets will be masked as it is for sensitive information
• Create variables and secrets as discussed
• Execute the following workflow

---

on:
    push:
      branches:
        - main
env:
    GLOBAL_ENV_VAR: learning thoughts global
    ORG_NAME: xyz limited

jobs:
    vars-job:
        runs-on: ubuntu-latest
        steps:
            - name: print vars
              run: echo 'group = ${{ vars.GROUP_NAME }}  user = ${{ vars.USERNAME }} token = ${{ secrets.TOKEN  }}'

• Github automatically sets some environment variables which start with GITHUB_
  • GITHUB_WORKFLOW
  • GITHUB_RUN_ID
  • GITHUB_JOB
  • RUNNER_OS

Use output of one step in another

• Use the following yaml

MAVEN CI using github actions

• Lets create some variables at repo level with some default values for maven specifics
• Uploading test results
  • popular action
• Uploading test results example

---
name: Manual maven steps for ci
on:
    pull_request:
      branches: 
        - main
    workflow_dispatch:

jobs:
    manual:
        runs-on: ubuntu-24.04
        steps:
          - uses: actions/checkout@v5
          - uses: actions/setup-java@v5
            with:
                distribution: 'temurin'
                java-version: '21'
          - name: build package
            run: mvn ${{ vars.GOAL  }}
          - name: publish test results
            uses: EnricoMi/publish-unit-test-result-action@v2
            with:
              files: |
                **/target/surefire-reports/*.xml

• Now to upload jar files
• We can cache maven as there is support in setup-java action`

---
name: Manual maven steps for ci
on:
    pull_request:
      branches: 
        - main
    workflow_dispatch:

permissions:
  contents: read
  checks: write

jobs:
    manual:
        runs-on: ubuntu-24.04
        steps:
          - uses: actions/checkout@v5
          - uses: actions/setup-java@v5
            with:
                distribution: 'temurin'
                java-version: '21'
                cache: maven
          - name: build package
            run: mvn ${{ vars.GOAL  }}
          - name: publish test results
            uses: EnricoMi/publish-unit-test-result-action@v2
            with:
              files: |
                **/target/surefire-reports/*.xml

          - name: Uploading packaged jar files
            uses: actions/upload-artifact@v4
            with:
              name: spring-petclinic-jar
              path: '**/target/*.jar'

matrix

• Refer Here for matrix

---
name: Manual maven steps for ci
on:
    pull_request:
      branches: 
        - main
    workflow_dispatch:

permissions:
  contents: read
  checks: write
  pull-requests: write

jobs:
    manual:
        runs-on: ubuntu-24.04
        strategy:
          fail-fast: false
          matrix:
            java: [17, 21]

        steps:
          - uses: actions/checkout@v5
          - uses: actions/setup-java@v5
            with:
                distribution: 'temurin'
                java-version: ${{ matrix.java }}
                cache: maven
          - name: build package
            run: mvn ${{ vars.GOAL  }}
          - name: publish test results
            uses: EnricoMi/publish-unit-test-result-action@v2
            with:
              files: |
                **/target/surefire-reports/*.xml

          - name: Uploading packaged jar files
            uses: actions/upload-artifact@v4
            with:
              name: spring-petclinic-${{ matrix.java }}.jar
              path: '**/target/*.jar'

Conditions and functions

• Expressions Refer Here