ci: Run on push to main and workflow_dispatch (#3)

* Allow for PRs to run build tests but don't deploy unless on main.
  If need to delploy on a non-main branch then use workflow_dispatch.

.github/workflows/CI.yaml

@@ -1,12 +1,18 @@
 name: Build AnalysisBase ML image
+
 on:
   push:
     branches:
-      - "**"
+      - main
     tags:
       - "v*.*.*"
+  pull_request:
+    branches:
+      - main
+  workflow_dispatch:
   repository_dispatch:
     types: gitops-analysis-base-trigger
+
 jobs:
   docker:
     runs-on: ubuntu-latest
@@ -21,7 +27,7 @@ jobs:
           # list of Docker images to use as base name for tags
           images: |
             sslhep/analysis-dask-uc
-            hub.opensciencegrid.org/usatlas/analysis-dask-uc           
+            hub.opensciencegrid.org/usatlas/analysis-dask-uc
           # generate Docker tags based on the following events/attributes
           tags: |
             type=ref,event=branch
@@ -36,25 +42,38 @@ jobs:
         uses: docker/[email protected]
 
       - name: Login to Docker Hub
+        if: github.event_name != 'pull_request'
         uses: docker/[email protected]
         with:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
 
-
       - name: Login to Harbor Container Registry
+        if: github.event_name != 'pull_request'
         uses: docker/login-action@v3
         with:
           registry: hub.opensciencegrid.org
           username: ${{ secrets.HARBOR_USERNAME }}
           password: ${{ secrets.HARBOR_PASSWORD }}
 
+      - name: Test build
+        if: github.event_name == 'pull_request'
+        uses: docker/[email protected]
+        with:
+          context: .
+          file: Dockerfile
+          load: true
+          push: false
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+
       - name: Build and push
+        if: github.event_name != 'pull_request'
         uses: docker/[email protected]
         with:
           context: .
           file: Dockerfile
-          push: true          
+          push: true
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}