Overview

Teaching: 5 min
Exercises: 5 min

Questions

• How do you make some jobs run after other jobs?

Objectives

• Run some jobs in serial.

Defining dependencies

From the last session, we’re starting with

jobs:
  greeting:
   runs-on: ubuntu-latest
   steps:
     - run: echo hello world

 build_skim:
   runs-on: ubuntu-latest
   container: rootproject/root:${{ matrix.version }}
   strategy:
     matrix:
       version: [6.26.10-conda, latest]
   steps:
     - name: checkout repository
       uses: actions/checkout@v4

     - name: build
       run: |
        COMPILER=$(root-config --cxx)
        FLAGS=$(root-config --cflags --libs)
        $COMPILER -g -O3 -Wall -Wextra -Wpedantic -o skim skim.cxx $FLAGS

We’re going to talk about another useful parameter needs.

Specify dependencies between jobs

The key-value needs: job or list of jobs allows you to specify dependencies between jobs in the order you define.
Example:

job2:
  needs: job1

job2 waits until job1 completes successfully. Further reading.

Dependent jobs

How to make build_skim job to run after greeting?

Solution

jobs:
 greeting:
   runs-on: ubuntu-latest
   steps:
     - run: echo hello world

build_skim:
  needs: greeting
  runs-on: ubuntu-latest
  container: rootproject/root:${{ matrix.version }}
  strategy:
    matrix:
      version: [6.26.10-conda, latest]
  steps:
    - name: checkout repository
      uses: actions/checkout@v4

    - name: build
      run: |
        COMPILER=$(root-config --cxx)
        FLAGS=$(root-config --cflags --libs)
        $COMPILER -g -O3 -Wall -Wextra -Wpedantic -o skim skim.cxx $FLAGS

Let’s go ahead and add those changes and look at GitHub.

git add .github/workflows/main.yml
git commit -m "add dependent jobs"
git push -u origin feature/add-actions

Key Points

• We can specify dependencies between jobs running in a series using the needs value.