he GitHub social coding platform introduced GitHub Actions as a way to automate different aspects of collaborative software development through the use of workflow files. It is the most popular CI/CD and workflow automation tool for GitHub. To maintain workflow code over time, it is useful to rely on differencing tools to identify the changes made during successive commits. Unfortunately, existing code differencing tools are not able to correctly identify changes made to workflow files. We therefore implemented gawd, a syntactic differencing tool for GitHub Actions workflows. The tool is capable of reporting the addition, deletion, modification and move of syntactic components in workflow files, taking into account the specific syntax of workflows. gawd has been evaluated on manually classified sets of workflow changes taken from existing commits in 40 different GitHub repositories, and was able to successfully identify these changes. gawd is publicly released as an open source Python tool distributed on PyPI.

1. gawd: A Differencing Tool for GitHub Actions
Workflows
Pooya Rostami Mazrae, Alexandre Decan, Tom Mens
University of Mons, Belgium
MSR 2024

2. Evolution of GitHub Actions workflow files
2
Proportion of touched lines of code.
Number of modified lines of code.
Number of added lines of code.
A Preliminary Study of GitHub Actions Workflow Changes, SATToSE 2023,
https://ceur-ws.org/Vol-3483/paper8.pdf

3. Example of a workflow file diff
3

4. Expected output
4
remove on.pull_request
change on.push from (all branches) to (branches: [master, develop])

5. Expected output
5
rename jobs.build to jobs.build-analyse
add jobs.build-analyse.name with 'build and analysis'

6. Expected output
6
move jobs.build.steps[1] to jobs.build-analyse.steps[0]
change jobs.build.steps[1].name from 'Set up with Java 11' to 'Set up with Java 17'
change jobs.build.steps[1].uses from 'actions/setup-java@v1' to 'actions/setup-java@v3’
add jobs.build-analyse.steps[0].with.distribution with 'temurin'
add jobs.build-analyse.steps[0].with.cache with 'maven’
change jobs.build.steps[1].with.java-version from 11 to 17
move jobs.build.steps[0] to jobs.build-analyse.steps[1]
change jobs.build.steps[0].uses from 'actions/checkout@v2' to 'actions/checkout@v3'

7. Expected output
7
add jobs.build-analyse.steps[3]

8. About gawd
• Open source tool
• How does it work?
• Evaluation
• Configuring gawd
8
gawd first second
[--help] [--threshold X] [--position-weight X]
[--job-name-weight X] [--short] [--json] [--verbose]

9. 9
% gawd old_version.yaml new_version.yaml –short
removed on.pull_request with None
changed on.push from None to {'branches': ['maste (...) develop’]}
renamed jobs.build to jobs.build-analyse
added jobs.build-analyse.name with 'build and analysis’
moved jobs.build.steps[0] to jobs.build-analyse.steps[1]
changed jobs.build.steps[0].uses from 'actions/checkout@v2' to 'actions/checkout@v3’
moved jobs.build.steps[3] to jobs.build-analyse.steps[4]
added jobs.build-analyse.steps[4].with.generate-summary with True
moved jobs.build.steps[1] to jobs.build-analyse.steps[0]
changed jobs.build.steps[1].name from 'Set up with Java 11' to 'Set up with Java 17’
changed jobs.build.steps[1].uses from 'actions/setup-java@v1' to 'actions/setup-java@v3’
added jobs.build-analyse.steps[0].with.distribution with 'temurin’
added jobs.build-analyse.steps[0].with.cache with 'maven’
changed jobs.build.steps[1].with.java-version from 11 to 17
added jobs.build-analyse.steps[3] with {'name': 'Publish Te (...) eport@v1'}
gawd output
9

10. 10
https://github.com/pooya-rostami/gawd
pip install gawd