name: Deploy backend to beta VPS

# On a push to `main`, SSH to beta and roll ONLY the backend service onto the
# image build-push.yml just published for this commit. Frontend is deployed
# independently by its own repo's deploy.yml -- that is the whole point of the
# FE/BE CI-CD split: a backend change ships without touching frontend and vice
# versa. thermograph-infra/deploy/deploy.sh persists each service's live tag
# host-side, so a single-service roll never disturbs the other.
#
# The SSH_HOST/USER/KEY/PORT secrets point at beta. Prod deploys the same way
# from deploy-prod.yml (release branch, PROD_SSH_* secrets). appleboy/ssh-action is
# referenced by full GitHub URL because it isn't mirrored in Forgejo's default
# action registry.
#
# The tag MUST match build-push.yml's `sha-${GITHUB_SHA:0:12}` (12 hex), not
# the full 40-char ${{ github.sha }} -- default Actions expressions have no
# substring function, so the compute step below truncates it. deploy.sh also
# retries the pull for ~5 min because Forgejo `needs:` can't gate across the
# separate build-push.yml, so this push's build may still be in flight.

on:
  push:
    branches: [main]
  workflow_dispatch: {}

concurrency:
  group: beta-deploy-backend
  cancel-in-progress: false

jobs:
  deploy:
    runs-on: docker
    steps:
      - name: Compute image tag
        id: tag
        run: echo "tag=sha-${GITHUB_SHA:0:12}" >> "$GITHUB_OUTPUT"

      - name: Deploy backend over SSH
        uses: https://github.com/appleboy/ssh-action@v1.2.0
        with:
          host: ${{ secrets.SSH_HOST }}
          username: ${{ secrets.SSH_USER }}
          key: ${{ secrets.SSH_KEY }}
          port: ${{ secrets.SSH_PORT }}
          # Forward the target service + the image tag to run. deploy.sh reads
          # BACKEND_IMAGE_TAG and rolls just `backend`.
          envs: SERVICE,BACKEND_IMAGE_TAG
          script: /opt/thermograph/deploy/deploy.sh
        env:
          SERVICE: backend
          BACKEND_IMAGE_TAG: ${{ steps.tag.outputs.tag }}