add check to build containers

.github/workflows/ci.yml

@@ -49,4 +49,27 @@ jobs:
 
     # TODO add testing for frontend
     # - name: Run tests
-    #   run: cd frontend && npm test
+    #   run: cd frontend && npm test
+  backend-build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Build backend Docker container
+        working-directory: backend
+        run: |
+          docker build -t backend .
+      
+  frontend-build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+
+      - name: Build frontend Docker container
+        working-directory: frontend
+        run: |
+          docker build -t frontend .