🌱 Add KAL linter for linting API conventions

.github/workflows/pr-golangci-lint.yaml

@@ -33,3 +33,5 @@ jobs:
           version: v1.63.4
           args: --out-format=colored-line-number
           working-directory: ${{matrix.working-directory}}
+      - name: Lint API
+        run: GOLANGCI_LINT_EXTRA_ARGS=--out-format=colored-line-number make lint-api

.golangci-kal.yml

@@ -0,0 +1,62 @@
+run:
+  timeout: 10m
+  go: "1.23"
+  allow-parallel-runners: true
+
+linters:
+  disable-all: true
+  enable:
+    - kal # linter for Kube API conventions
+
+linters-settings:
+  custom:
+    kal:
+      type: "module"
+      description: KAL is the Kube-API-Linter and lints Kube like APIs based on API conventions and best practices.
+      settings:
+        linters:
+          enable:
+          # Per discussion in July 2024, we are keeping phase fields for now.
+          # See https://github.com/kubernetes-sigs/cluster-api/pull/10897#discussion_r1685929508
+          # and https://github.com/kubernetes-sigs/cluster-api/pull/10897#discussion_r1685919394.
+          # - "nophase" # Phase fields are discouraged by the Kube API conventions, use conditions instead.
+
+          # Linters below this line are disabled, pending conversation on how and when to enable them.
+          # - "conditions" # Ensure conditions have the correct json tags and markers.
+          # - "commentstart" # Ensure comments start with the serialized version of the field name.
+          # - "integers" # Ensure only int32 and int64 are used for integers.
+          # - "jsontags" # Ensure every field has a json tag.
+          # - "maxlength" # Ensure all strings and arrays have maximum lengths/maximum items.
+          # - "nobools" # Bools do not evolve over time, should use enums instead.
+          # - "optionalorrequired" # Every field should be marked as `+optional` or `+required`.
+          # - "requiredfields" # Required fields should not be pointers, and should not have `omitempty`.
+          # - "statussubresource" # All root objects that have a `status` field should have a status subresource.
+          disable:
+          - "*" # We will manually enable new linters after understanding the impact. Disable all by default.
+        lintersConfig:
+          conditions:
+            isFirstField: Warn # Require conditions to be the first field in the status struct.
+            usePatchStrategy: Forbid # Conditions should not use the patch strategy on CRDs.
+            useProtobuf: Forbid # We don't use protobuf, so protobuf tags are not required.
+        # jsonTags:
+        #   jsonTagRegex: "^[a-z][a-z0-9]*(?:[A-Z][a-z0-9]*)*$" # The default regex is appropriate for our use case.
+        # optionalOrRequired:
+        #   preferredOptionalMarker: optional | kubebuilder:validation:Optional # The preferred optional marker to use, fixes will suggest to use this marker. Defaults to `optional`.
+        #   preferredRequiredMarker: required | kubebuilder:validation:Required # The preferred required marker to use, fixes will suggest to use this marker. Defaults to `required`.
+        # requiredFields:
+        #   pointerPolicy: Warn | SuggestFix # Defaults to `SuggestFix`. We want our required fields to not be pointers.
+
+issues:
+  exclude-files:
+    - "zz_generated.*\\.go$"
+    - "vendored_openapi\\.go$"
+    # We don't want to invest time to fix new linter findings in old API types.
+    - "internal/apis/.*"
+    - ".*_test.go"  # Exclude test files.
+  max-same-issues: 0
+  max-issues-per-linter: 0
+  exclude-rules:
+  # KAL should only run on API folders.
+  - path-except: "api/*"
+    linters:
+      - kal

.golangci.yml

@@ -226,6 +226,7 @@ linters-settings:
       - name: constant-logical-expr
   goconst:
     ignore-tests: true
+
 issues:
   exclude-files:
     - "zz_generated.*\\.go$"

Makefile

@@ -164,6 +164,10 @@ GOLANGCI_LINT_VER := $(shell cat .github/workflows/pr-golangci-lint.yaml | grep
 GOLANGCI_LINT := $(abspath $(TOOLS_BIN_DIR)/$(GOLANGCI_LINT_BIN)-$(GOLANGCI_LINT_VER))
 GOLANGCI_LINT_PKG := github.com/golangci/golangci-lint/cmd/golangci-lint
 
+GOLANGCI_LINT_KAL_BIN := golangci-lint-kal
+GOLANGCI_LINT_KAL_VER := $(shell cat ./hack/tools/.custom-gcl.yaml | grep name: | sed 's/name: golangci-lint-kal-//')
+GOLANGCI_LINT_KAL := $(abspath $(TOOLS_BIN_DIR)/$(GOLANGCI_LINT_KAL_BIN)-$(GOLANGCI_LINT_KAL_VER))
+
 GOVULNCHECK_BIN := govulncheck
 GOVULNCHECK_VER := v1.1.4
 GOVULNCHECK := $(abspath $(TOOLS_BIN_DIR)/$(GOVULNCHECK_BIN)-$(GOVULNCHECK_VER))
@@ -653,11 +657,12 @@ generate-test-infra-prowjobs: $(PROWJOB_GEN) ## Generates the prowjob configurat
 ##@ lint and verify:
 
 .PHONY: lint
-lint: $(GOLANGCI_LINT) ## Lint the codebase
+lint: $(GOLANGCI_LINT) $(GOLANGCI_LINT_KAL) ## Lint the codebase
 	$(GOLANGCI_LINT) run -v $(GOLANGCI_LINT_EXTRA_ARGS)
 	cd $(TEST_DIR); $(GOLANGCI_LINT) run --path-prefix $(TEST_DIR) --config $(ROOT_DIR)/.golangci.yml -v $(GOLANGCI_LINT_EXTRA_ARGS)
 	cd $(TOOLS_DIR); $(GOLANGCI_LINT) run --path-prefix $(TOOLS_DIR) --config $(ROOT_DIR)/.golangci.yml -v $(GOLANGCI_LINT_EXTRA_ARGS)
 	./scripts/lint-dockerfiles.sh $(HADOLINT_VER) $(HADOLINT_FAILURE_THRESHOLD)
+	$(GOLANGCI_LINT_KAL) run -v --config $(ROOT_DIR)/.golangci-kal.yml $(GOLANGCI_LINT_EXTRA_ARGS)
 
 .PHONY: lint-dockerfiles
 lint-dockerfiles:
@@ -667,6 +672,14 @@ lint-dockerfiles:
 lint-fix: $(GOLANGCI_LINT) ## Lint the codebase and run auto-fixers if supported by the linter
 	GOLANGCI_LINT_EXTRA_ARGS=--fix $(MAKE) lint
 
+.PHONY: lint-api
+lint-api: $(GOLANGCI_LINT_KAL)
+	$(GOLANGCI_LINT_KAL) run -v --config $(ROOT_DIR)/.golangci-kal.yml $(GOLANGCI_LINT_EXTRA_ARGS)
+
+.PHONY: lint-api-fix
+lint-api-fix: $(GOLANGCI_LINT_KAL)
+	GOLANGCI_LINT_EXTRA_ARGS=--fix $(MAKE) lint-api
+
 .PHONY: tiltfile-fix
 tiltfile-fix: ## Format the Tiltfile
 	TRACE=$(TRACE) ./hack/verify-starlark.sh fix
@@ -1492,6 +1505,9 @@ $(GINKGO): # Build ginkgo from tools folder.
 $(GOLANGCI_LINT): # Build golangci-lint from tools folder.
 	GOBIN=$(TOOLS_BIN_DIR) $(GO_INSTALL) $(GOLANGCI_LINT_PKG) $(GOLANGCI_LINT_BIN) $(GOLANGCI_LINT_VER)
 
+$(GOLANGCI_LINT_KAL): $(GOLANGCI_LINT) # Build golangci-lint-kal from custom configuration.
+	cd $(TOOLS_DIR); $(GOLANGCI_LINT) custom
+
 $(GOVULNCHECK): # Build govulncheck.
 	GOBIN=$(TOOLS_BIN_DIR) $(GO_INSTALL) $(GOVULNCHECK_PKG) $(GOVULNCHECK_BIN) $(GOVULNCHECK_VER)
 

hack/tools/.custom-gcl.yaml

@@ -0,0 +1,6 @@
+version:  v1.63.4
+name: golangci-lint-kal-v1.63.4
+destination: ./bin
+plugins:
+- module: 'github.com/JoelSpeed/kal'
+  version: v0.0.0-20250208110507-b94e5ede1177