lint: Introduce a golang linter

.github/workflows/kubectl-aks.yml

@@ -65,6 +65,26 @@ jobs:
           name: kubectl-aks-${{ matrix.os }}-${{ matrix.arch }}-tar-gz
           path: kubectl-aks-${{ matrix.os }}-${{ matrix.arch }}.tar.gz
 
+  lint:
+    name: Run linter
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Setup go
+        uses: actions/setup-go@v4
+        with:
+          go-version: ${{ env.GO_VERSION }}
+          check-latest: true
+      - name: Lint
+        uses: golangci/golangci-lint-action@v3.5.0
+        with:
+          # This version number must be kept in sync with Makefile lint one.
+          version: v1.53.2
+          working-directory: /home/runner/work/kubectl-aks/kubectl-aks
+          # Workaround to display the output:
+          # https://github.com/golangci/golangci-lint-action/issues/119#issuecomment-981090648
+          args: "--out-${NO_FUTURE}format colored-line-number"
+
   unit-tests:
     name: Run unit tests
     runs-on: ubuntu-latest

.golangci.yml

@@ -0,0 +1,41 @@
+output:
+  sort-results: true
+
+run:
+  timeout: 10m
+
+issues:
+  exclude-use-default: false
+  max-same-issues: 0
+  max-issues-per-linter: 0
+  exclude-rules:
+    # Ignore check: Packages must have a package comment
+    - text: "ST1000: at least one file in a package should have a package comment"
+      linters:
+        - stylecheck
+
+linters:
+  disable-all: true
+  enable:
+    - gofumpt
+    - stylecheck
+    - staticcheck
+    - errorlint
+
+linters-settings:
+  gofumpt:
+    lang-version: "1.17"
+  staticcheck:
+    go: "1.17"
+    checks: ["all"]
+  stylecheck:
+    go: "1.17"
+    checks: ["all"]
+  errorlint:
+    # https://github.com/polyfloyd/go-errorlint
+    # Check whether fmt.Errorf uses the %w verb for formatting errors.
+    errorf: true
+    # Check for plain type assertions and type switches (errors.As must be used).
+    asserts: true
+    # Check for plain error comparisons (errors.Is must be used)
+    comparison: true

Makefile

@@ -12,6 +12,8 @@ else
 	VERSION := $(TAG)-dirty
 endif
 
+LINTER_VERSION ?= v1.53.2
+
 LDFLAGS := "-X github.com/Azure/kubectl-aks/cmd.version=$(VERSION) -extldflags '-static'"
 
 .DEFAULT_GOAL := kubectl-aks
@@ -49,6 +51,14 @@ kubectl-aks-%: phony_explicit
 		-o kubectl-aks-$${GOOS}-$${GOARCH} \
 		github.com/Azure/kubectl-aks
 
+# Lint
+.PHONY: lint
+lint:
+	docker run --rm --env XDG_CACHE_HOME=/tmp/xdg_home_cache \
+		--env GOLANGCI_LINT_CACHE=/tmp/golangci_lint_cache \
+		--user $(shell id -u):$(shell id -g) -v $(shell pwd):/app -w /app \
+		golangci/golangci-lint:$(LINTER_VERSION) golangci-lint run
+
 # Install
 .PHONY: install
 install: kubectl-aks