GitHub: add CI

.github/workflows/main.yml

@@ -0,0 +1,53 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - "master"
+  pull_request:
+    branches:
+      - "*"
+
+defaults:
+  run:
+    shell: bash
+
+env:
+  # go needs absolute directories, using the $HOME variable doesn't work here.
+  GOCACHE: /home/runner/work/go/pkg/build
+  GOPATH: /home/runner/work/go
+  GO_VERSION: 1.18.4
+
+jobs:
+  ########################
+  # lint code
+  ########################
+  lint:
+    name: lint code
+    runs-on: ubuntu-latest
+    steps:
+      - name: git checkout
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: lint
+        run: make lint
+
+  ########################
+  # run unit tests
+  ########################
+  unit-test:
+    name: run unit tests
+    runs-on: ubuntu-latest
+    steps:
+      - name: git checkout
+        uses: actions/checkout@v2
+
+      - name: setup go ${{ env.GO_VERSION }}
+        uses: actions/setup-go@v2
+        with:
+          go-version: '${{ env.GO_VERSION }}'
+
+      - name: run unit tests
+        run: make unit