Add image build gate

We already publish the image to quay.io/airshipit/sip using Quay
triggers on every push to the main branch; however, we do not verify
that the image will build before merging. This commit adds a simple job
to verify that the image will build before merging.

.github/workflows/docker-build.yaml

@@ -0,0 +1,18 @@
+name: Build Docker Image
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build Docker image
+      run: make docker-build

Makefile

@@ -65,7 +65,7 @@ generate: controller-gen
 	$(CONTROLLER_GEN) object:headerFile="hack/boilerplate.go.txt" paths="./..."
 
 # Build the docker image
-# If DOCKER_PROXY_FLAGS values are empty, we are fine with that 
+# If DOCKER_PROXY_FLAGS values are empty, we are fine with that
 docker-build:
 	docker build ${DOCKER_PROXY_FLAGS} . -t ${IMG}
 
@@ -80,7 +80,7 @@ kind-create:
 # Build docker container and load it into running kind cluster
 kind-load-image: docker-build
 	kind load docker-image ${IMG} --name ${KIND_CLUSTER_NAME}
-    
+
 # find or download controller-gen
 # download controller-gen if necessary
 controller-gen:

README.md

@@ -1,5 +1,7 @@
 # SIP Cluster Operator
 
+[![Docker Repository on Quay](https://quay.io/repository/airshipit/sip/status "Docker Repository on Quay")](https://quay.io/repository/airshipit/sip)
+
 ## Overview
 
 The lifecycle of the VM's and their relationship to Cluster will be managed using two operators: vNode-Operator(ViNO) and the Support Infra Provider Operator (SIP) .