Migrate from CircleCI to GitHub Actions for tests and releases (#27)

This also enables linting via `actionlint` and `golangci-lint`. The Contributing Guide is updated with information how to run tooling locally and prepare releases using the new process.

Author: bflad

.circleci/config.yml

@@ -127,11 +127,61 @@ We belive that one should "leave the campsite cleaner than you found it", so
 you are welcome to clean up cosmetic issues in the neighbourhood when
 submitting a patch that makes functional changes or fixes.
 
+## Linting
+
+GitHub Actions workflow bug and style checking is performed via [`actionlint`](https://github.com/rhysd/actionlint).
+
+To run the GitHub Actions linters locally, install the `actionlint` tool, and run:
+
+```shell
+actionlint
+```
+
+Go code bug and style checking is performed via [`golangci-lint`](https://golangci-lint.run/).
+
+To run the Go linters locally, install the `golangci-lint` tool, and run:
+
+```shell
+golangci-lint run ./...
+```
+
 ## Testing
 
 Code contributions should be supported by unit tests wherever possible.
 
-### Unit tests
+### GitHub Actions Tests
+
+GitHub Actions workflow testing is performed via [`act`](https://github.com/nektos/act).
+
+To run the GitHub Actions testing locally (setting appropriate event):
+
+```shell
+act --artifact-server-path /tmp --env ACTIONS_RUNTIME_TOKEN=test -P ubuntu-latest=ghcr.io/catthehacker/ubuntu:act-latest pull_request
+```
+
+The command options can be added to a `~/.actrc` file:
+
+```text
+--artifact-server-path /tmp
+--env ACTIONS_RUNTIME_TOKEN=test
+-P ubuntu-latest=ghcr.io/catthehacker/ubuntu:act-latest
+```
+
+So they do not need to be specified every invocation:
+
+```shell
+act pull_request
+```
+
+### Go Unit Tests
+
+Go code unit testing is perfomed via Go's built-in testing functionality.
+
+To run the Go unit testing locally:
+
+```shell
+go test ./...
+```
 
 This codebase follows Go conventions for unit testing. Some guidelines include:
 
@@ -163,3 +213,37 @@ func TestExample(t *testing.T) {
     }
 }
 ```
+
+## Maintainers Guide
+
+This section is dedicated to the maintainers of this project.
+
+### Releases
+
+Before running a release, the changelog must be constructed from unreleased entries in the `.changelog` directory.
+
+Install the latest version of the [`changelog-build`](https://pkg.go.dev/github.com/hashicorp/go-changelog/cmd/changelog-build) command, if it not already available:
+
+```shell
+go install github.com/hashicorp/go-changelog/cmd/changelog-build
+```
+
+Run the [`changelog-build`](https://pkg.go.dev/github.com/hashicorp/go-changelog/cmd/changelog-build) command from the root directory of the repository:
+
+```shell
+changelog-build -changelog-template .changelog.tmpl -entries-dir .changelog -last-release $(git describe --tags --abbrev=0) -note-template .changelog-note.tmpl -this-release HEAD
+```
+
+This will generate a section of Markdown text for the next release. Open the `CHANGELOG.md` file, add a `# X.Y.Z` header as the first line, then add the output from the `changelog-build` command.
+
+Commit, push, create a release Git tag, and push the tag:
+
+```shell
+git add CHANGELOG.md
+git commit -m "Update CHANGELOG for v1.2.3"
+git push
+git tag v1.2.3
+git push --tags
+```
+
+GitHub Actions will pick up the new release tag and kick off the release workflow.

.github/CONTRIBUTING.md

@@ -0,0 +1,24 @@
+# Continuous integration handling for GitHub Actions workflows
+name: ci-github-actions
+
+on:
+  pull_request:
+    paths:
+      - .github/workflows/*.yml
+
+permissions:
+  contents: read
+
+jobs:
+  actionlint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - id: go-version
+        # Reference: https://github.com/actions/setup-go/issues/23
+        run: echo "::set-output name=version::$(cat ./.go-version)"
+      - uses: actions/setup-go@v2
+        with:
+          go-version: ${{ steps.go-version.outputs.version }}
+      - run: go install github.com/rhysd/actionlint/cmd/actionlint@latest
+      - run: actionlint

.github/workflows/ci-github-actions.yml

@@ -0,0 +1,48 @@
+# Continuous integration handling for Go
+name: ci-go
+
+on:
+  pull_request:
+    paths:
+      - .github/workflows/test.yml
+      - .golangci.yml
+      - .go-version
+      - go.mod
+      - '**.go'
+
+permissions:
+  contents: read
+
+jobs:
+  golangci-lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - id: go-version
+        # Reference: https://github.com/actions/setup-go/issues/23
+        run: echo "::set-output name=version::$(cat ./.go-version)"
+      - uses: actions/setup-go@v2
+        with:
+          go-version: ${{ steps.go-version.outputs.version }}
+      - run: go mod download
+      - uses: golangci/golangci-lint-action@v2
+        with:
+          skip-go-installation: true
+  test:
+    name: test (Go v${{ matrix.go-version }})
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go-version: [ '1.17', '1.16' ]
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-go@v2
+        with:
+          go-version: ${{ matrix.go-version }}
+      - run: go mod download
+      - run: go test -coverprofile=coverage.out ./...
+      - run: go tool cover -html=coverage.out -o coverage.html
+      - uses: actions/upload-artifact@v2
+        with:
+          name: go-${{ matrix.go-version }}-coverage
+          path: coverage.html

.github/workflows/ci-go.yml

@@ -0,0 +1,25 @@
+# Continuous integration handling for GoReleaser
+name: ci-goreleaser
+
+on:
+  pull_request:
+    paths:
+      - .goreleaser.yml
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - id: go-version
+        # Reference: https://github.com/actions/setup-go/issues/23
+        run: echo "::set-output name=version::$(cat ./.go-version)"
+      - uses: actions/setup-go@v2
+        with:
+          go-version: ${{ steps.go-version.outputs.version }}
+      - uses: goreleaser/goreleaser-action@v2
+        with:
+          args: check