Trigger a GitHub Action on a foreign repo update (push)

Question

I'm trying to mirror a public repo that I don't own, and more importantly mirror their pushes (to trigger another action).

Right now, the sync actions I have seen seem to copy paste a repo into a repo I own, but that repo's pushes don't trigger actions. Is there a way to do this ?

I don't know the foreign repo's owner. I'm aware that the owner could send a dispatch event, but I want a solution that doesn't rely on the goodwill of someone.

Basically, I want this to happen: My repo synchronizes with a foreign one every hour, and if there was an update in the last hour then another action gets triggered.

Is there a way to do this ?

Answer 1

For people with the same problem, I found a way through a cron schedule:

1. Create an empty text file in your repo
2. Check the original repo's commit id
3. If that id is different from the one in the text file, then trigger a sync Action (and optionally any other Action), and then add the commit id in a small text file
4. Otherwise, do nothing
5. Repeat from 2 on a cron schedule

Updates on the foreign repo will trigger on the cron schedule.

It's not exactly what I wanted, but close enough.

Edit: Here is a complete .yml file example from my repo, decommented to make it shorter

name: Sync+build+push TTRSS

on:
  schedule:
    - cron:  '0 0 * * *'
  workflow_dispatch:

jobs:
  get_commits:
    runs-on: ubuntu-latest
    outputs:
      LOCAL: ${{ steps.commits.outputs.SETLOCAL }}
      REMOTE: ${{ steps.commits.outputs.SETREMOTE }} 
    steps:
      - name: Checkout
        uses: actions/checkout@v2
        with:
          ref: 'TTRSS-docker'
      - name: set local and remote latest commit as environment variables
        id: commits
        run: |
          echo "::set-output name=SETREMOTE::$(git ls-remote https://git.tt-rss.org/fox/ttrss-docker-compose.git HEAD | awk '{ print $1 }')"
          echo "::set-output name=SETLOCAL::$(cat last_sync_with_original_repo_commit_id)"
  
  repo_sync:
    needs: [get_commits]
    runs-on: ubuntu-latest
    if: needs.get_commits.outputs.LOCAL != needs.get_commits.outputs.REMOTE
    steps:
      - name: repo-sync
        uses: wei/git-sync@v3
        with:
          source_repo: "https://git.tt-rss.org/fox/ttrss-docker-compose.git"
          source_branch: "master"
          destination_repo: "git@github.com:schklom/Mirror-workflows.git"
          destination_branch: "TTRSS-docker"
          ssh_private_key: ${{ secrets.GITSYNCACTION }}
      - name: Checkout
        uses: actions/checkout@v2
        with:
          ref: 'TTRSS-docker'
      - name: get most recent commit id on original repo, for next comparison on sync
        run: git ls-remote https://git.tt-rss.org/fox/ttrss-docker-compose.git HEAD | awk '{ print $1 }' > last_sync_with_original_repo_commit_id
      - name: Commit and push the change
        uses: stefanzweifel/git-auto-commit-action@v4
        with:
          commit_message: Add last_sync_with_original_repo_commit_id

  build_push:
    needs: [repo_sync]
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v2
        with:
          ref: 'TTRSS-docker'
      - name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      - name: Set up Docker Buildx
        id: buildx
        uses: docker/setup-buildx-action@v1
      - name: Login to Docker Hub
        uses: docker/login-action@v1
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}
      - name: Build and push TTRSS app
        uses: docker/build-push-action@v2
        with:
          context: ./app
          file: ./app/Dockerfile
          platforms: linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64
          pull: true
          push: true
          tags: |
            schklom/ttrss-app:latest
      - name: Build and push TTRSS web-nginx
        uses: docker/build-push-action@v2
        with:
          context: ./web-nginx
          file: ./web-nginx/Dockerfile
          platforms: linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64
          pull: true
          push: true
          tags: |
            schklom/ttrss-web-nginx:latest

  build_push_filelogging:
    needs: [build_push]
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v2
        with:
          ref: 'TTRSS-docker-with-filelogging'
      - name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      - name: Set up Docker Buildx
        id: buildx
        uses: docker/setup-buildx-action@v1
      - name: Login to Docker Hub
        uses: docker/login-action@v1
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}
      - name: Build and push TTRSS app (with file logging)
        uses: docker/build-push-action@v2
        with:
          context: ./
          file: ./Dockerfile
          platforms: linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64
          pull: true
          push: true
          tags: |
            schklom/ttrss-app:with-filelogging-latest