Makefile,github: implement make lint and centralize GOLANGCI_LINT_VERSION

Author: schuellerf

.github/workflows/tests.yml

@@ -13,9 +13,6 @@ on:
 
 env:
   GO_VERSION: 1.22
-  # see https://golangci-lint.run/product/changelog
-  # to select a version that supports the GO_VERSION given above
-  GOLANGCI_LINT_VERSION: v2.0.2
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
@@ -44,10 +41,14 @@ jobs:
       - name: Install libgpgme devel package
         run: sudo apt install -y libgpgme-dev libbtrfs-dev libdevmapper-dev
 
+      - name: Extract golangci-lint version from Makefile
+        id: golangci_lint_version
+        run: echo "GOLANGCI_LINT_VERSION=$(awk -F '=' '/^GOLANGCI_LINT_VERSION *=/{print $2}' Makefile)" >> "$GITHUB_OUTPUT"
+
       - name: Run golangci-lint
         uses: golangci/golangci-lint-action@v7
         with:
-          version: ${{ env.GOLANGCI_LINT_VERSION }}
+          version: ${{ steps.golangci_lint_version.outputs.GOLANGCI_LINT_VERSION }}
           args: --timeout 5m0s
           working-directory: bib
 

Makefile

@@ -1,6 +1,13 @@
 .PHONY: all
 all: build-binary build-container
 
+GOLANGCI_LINT_VERSION=v2.0.2
+GO_BINARY?=go
+
+# the fallback '|| echo "golangci-lint' really expects this file
+# NOT to exist! This is just a trigger to help installing golangci-lint
+GOLANGCI_LINT_BIN=$(shell which golangci-lint 2>/dev/null || echo "golangci-lint")
+
 .PHONY: help
 help:
 	@echo 'Usage:'
@@ -45,3 +52,14 @@ push-check: build-binary build-container test  ## run all checks and tests befor
 	    exit 1; \
 	fi
 	@echo "All looks good - congratulations"
+
+$(GOLANGCI_LINT_BIN):
+	@echo "golangci-lint does not seem to be installed"
+	@read -p "Press <ENTER> to install it or <CTRL>-c to abort"
+	$(GO_BINARY) install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@$(GOLANGCI_LINT_VERSION) || \
+	( echo "if the go version is a problem, you can set GO_BINARY e.g. GO_BINARY=go.1.23.8 \
+	      after installing it e.g. go install golang.org/dl/go1.23.8@latest" ; exit 1 )
+
+.PHONY: lint
+lint: $(GOLANGCI_LINT_BIN)  ## run the linters to check for bad code
+	cd bib && $(GOLANGCI_LINT_BIN) run