👷(argocd) notify argocd when new images are pushed

Add a new job in the CI, which notifies ArgoCD through a webhook that a new
docker image has been pushed to the Docker registry. Thus, ArgoCD can sync
and pull the latest image.

Thus, main will be automatically deployed to staging.

.github/workflows/docker-hub.yml

@@ -80,3 +80,25 @@ jobs:
           push: ${{ github.event_name != 'pull_request' }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+
+  notify-argocd:
+    needs:
+      - build-and-push-frontend
+      - build-and-push-backend
+    runs-on: ubuntu-latest
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v4
+      -
+        name: Load sops secrets
+        uses: rouja/actions-sops@main
+        with:
+          secret-file: .github/workflows/secrets.enc.env
+          age-key: ${{ secrets.SOPS_PRIVATE }}
+      -
+        name: Call argocd github webhook
+        run: |
+          data='{"ref": "'$GITHUB_REF'","repository": {"html_url":"'$GITHUB_SERVER_URL'/'$GITHUB_REPOSITORY'"}}'
+          sig=$(echo -n ${data} | openssl dgst -sha1 -hmac ''${ARGOCD_WEBHOOK_SECRET}'' | awk '{print "X-Hub-Signature: sha1="$2}')
+          curl -X POST -H 'X-GitHub-Event:push' -H "Content-Type: application/json" -H "${sig}" --data "${data}" $ARGOCD_WEBHOOK_URL