Add a GitHub action for building nightly images

Signed-off-by: rick <rick@jenkins-zh.cn>

.github/workflows/nightly-builds.yml

@@ -0,0 +1,66 @@
+name: NightlyBuild
+
+on:
+  schedule:
+    # This is a UTC time
+    - cron: "0 16 * * *"
+  # Keep it only for test purpose, comment it once everything is ok
+  workflow_dispatch:
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    env:
+      GO111MODULE: on
+    steps:
+
+      - name: Set up Go 1.13
+        uses: actions/setup-go@v1
+        with:
+          go-version: 1.13
+        id: go
+
+      - name: Check out code into the Go module directory
+        uses: actions/checkout@v2
+
+      - name: Downloading go dependencies
+        run: go mod vendor
+
+      - name: Install kubebuilder
+        run: bash hack/install_kubebuilder.sh
+
+      - name: Build
+        run: make all
+
+      - name: Make OpenAPI Spec
+        run: make openapi
+
+      - name: Build and push docker images
+        env:
+          DOCKER_USERNAME: ${{ secrets.DOCKER_USERNAME }}
+          DOCKER_PASSWORD: ${{ secrets.DOCKER_PASSWORD }}
+        run: |
+          echo ${{ secrets.DOCKER_PASSWORD }} | docker login -u ${{ secrets.DOCKER_USERNAME }} --password-stdin
+          bash hack/docker_build.sh master
+
+          if [[ $? == 0 ]]; then
+            tag=nightly-$(date '+%Y%m%d')
+
+            docker tag kubespheredev/ks-apiserver kubespheredev/ks-apiserver:${tag}
+            docker tag kubespheredev/ks-controller-manager kubespheredev/ks-controller-manager:${tag}
+
+            docker push kubespheredev/ks-apiserver:${tag}
+            docker push kubespheredev/ks-controller-manager:${tag}
+          else
+            exit -1
+          fi
+
+      - name: slack
+        uses: 8398a7/action-slack@v3
+        env:
+          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}
+        with:
+          status: ${{ job.status }}
+          fields: repo,message,commit,author,action,eventName,ref,workflow,job,took
+        if: always()