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🌱 A GitHub Action that helps move workloads into greener time periods

Description

This action uses the Carbon Aware SDK/API to calculate if a job should be delayed in order to reduce the carbon footprint.

It does so by:

1. Collecting the current emission rating at the datacenter where the job is running
2. Comparing the current emission rating with the forecasted emission rating for that same datacenter
3. If the forecasted emission rating is lower than the current one, then a job delay will be calculated
4. If that delay is within the user-defined delay tolerance then the job can be paused accordingly

💡 Due to limitaitons in the GitHub Actions API, two workflows are needed in order to pause the job, please see below for details.

Usage

Main workflow

The workflow below invokes this action. If used in combination with the retriggering workflow (see below), the workflow run is automatically re-triggered, and delayed for X number of minutes.

name: Test Jord

on:
  workflow_dispatch:

jobs:
  job1:
    name: Job to delay (if needed)
    runs-on: ubuntu-latest
    environment: 
      name: green-delay
    steps:  
      - name: Job to delay (if needed)
        continue-on-error: false
        uses: stebje/[email protected]
        with:
          token: ${{ secrets.GREENTOKEN }}
          delay-tolerance: 100
          base-url-carbon-aware-api: 'https://carbon-aware-api.azurewebsites.net'
          environment-name: 'green-delay'
      - run: echo 'This step, and subsequent ones, will not run if the job is delayed'

Retriggering workflow

Since a workflow cannot retrigger itself from within an action, a separate, simple, workflow is needed for that. The workflow below used in combination with the one above, will ensure that the job is paused according to the calculated job delay.

The workflow is configured to avoid infinite loops using an if condition.

name: Rerun delayed workflow

on:
  workflow_run:
    workflows: [Test Jord]
    types: [completed]

jobs:
  re-run-job:
    name: Rerun a delayed workflow
    runs-on: ubuntu-latest
    if: ${{ github.event.workflow_run.run_attempt == 1 }}
    steps:
      - uses: actions/github-script@v6
        id: rerun-wf
        with:
          github-token: ${{ secrets.GREENTOKEN }}
          script: |
            github.rest.actions.reRunWorkflow({
              owner: context.repo.owner,
              repo: context.repo.repo,
              run_id: context.payload.workflow_run.id
            })

Action Inputs

Name	Description	Default	Required
token	GitHub Personal Access Token (PAT) with write:repo and write:workflow scope		true
delay-tolerance	The max number of minutes the job can be delayed	5	false
base-url-carbon-aware-api	The base URL of the host where the Carbon aware WebAPI is deployed	https://carbon-aware-api.azurewebsites.net	false
environment-name	Desired name of the repository environment that will be created and used to delay the job	green-delay	false

Known limitations

(please see below for future improvements addressing the limitations listed here)

• There is no way currently to ensure that the delayed job will run in the same datacenter as the one originally assigned to. This is due to how GitHub Actions allocates hosted runners.
• Only GitHub-hosted runners are supported at the moment, not self-hosted runners
• Only Linux and Windows runners are supported at the moment, not macOS

Future improvements

(insert)

Contributing

👉 How to contribute

👉 Code of Conduct

License

👉 MIT