Add github workflow. (proxy-wasm#6)

Signed-off-by: John Plevyak <[email protected]>

Author: jplevyak

.github/workflows/cpp.yml

@@ -0,0 +1,73 @@
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: C++
+
+on:
+
+  pull_request:
+    branches:
+    - master
+
+  push:
+    branches:
+    - master
+
+jobs:
+
+  format:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Format (clang-format)
+      run: |
+        sudo apt-get install clang-format-9
+        find . -name "*.h" -o -name "*.cc" -o -name "*.proto" | grep -v ".pb." | xargs -n1 clang-format-9 -i
+        git diff --exit-code
+
+    - name: Format (buildifier)
+      run: |
+        go get -u github.com/bazelbuild/buildtools/buildifier
+        export PATH=$PATH:$(go env GOPATH)/bin
+        find . -name "BUILD" | xargs -n1 buildifier -mode=check
+    - name: Format (addlicense)
+      run: |
+        go get -u github.com/google/addlicense
+        export PATH=$PATH:$(go env GOPATH)/bin
+        addlicense -check .
+
+  build:
+    runs-on: ubuntu-latest
+    
+    steps:
+    - uses: actions/checkout@v1
+
+    - name: Mount bazel cache
+      uses: actions/cache@v1
+      with:
+        path: "/home/runner/.cache/bazel"
+        key: bazel
+
+    - name: Install bazelisk
+      run: |
+        curl -LO "https://github.com/bazelbuild/bazelisk/releases/download/v1.1.0/bazelisk-linux-amd64"
+        mkdir -p "${GITHUB_WORKSPACE}/bin/"
+        mv bazelisk-linux-amd64 "${GITHUB_WORKSPACE}/bin/bazel"
+        chmod +x "${GITHUB_WORKSPACE}/bin/bazel"
+
+    - name: Test
+      run: |
+        "${GITHUB_WORKSPACE}/bin/bazel" test //...