ci: go linter config and ci workflow (#1)

.github/workflows/golangci-lint.yml

@@ -0,0 +1,24 @@
+name: Go - Lint
+on:
+  push:
+    branches:
+    - main
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  golangci:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - uses: actions/setup-go@v4
+      with:
+        go-version: '1.21'
+        cache: false
+    - name: golangci-lint
+      uses: golangci/golangci-lint-action@v3
+      with:
+        version: v1.54

.golangci.yml

@@ -0,0 +1,62 @@
+linters-settings:
+  funlen:
+    lines: 100
+    statements: 50
+  gocyclo:
+    min-complexity: 15
+  goimports:
+    local-prefixes: github.com/aabouzaid/kustomize-plugin-merger
+  govet:
+    check-shadowing: true
+  misspell:
+    locale: US
+  nolintlint:
+    allow-leading-space: false # require machine-readable nolint directives (with no leading space)
+    allow-unused: false # report any unused nolint directives
+    require-explanation: true # require an explanation for nolint directives
+    require-specific: false # don't require nolint directives to be specific about which linter is being skipped
+  revive:
+    confidence: 0
+
+linters:
+  disable-all: true
+  enable:
+    - bodyclose
+    - dogsled
+    - dupl
+    - errcheck
+    - exportloopref
+    - funlen
+    - gochecknoinits
+    - gocritic
+    - goconst
+    - gocyclo
+    - gofumpt
+    - goimports
+    - revive
+    - rowserrcheck
+    - goprintffuncname
+    - gosec
+    - gosimple
+    - govet
+    - ineffassign
+    - misspell
+    - nakedret
+    - noctx
+    - nolintlint
+    - staticcheck
+    - stylecheck
+    - sqlclosecheck
+    - typecheck
+    - unconvert
+    - unparam
+    - unused
+    - whitespace
+
+issues:
+  # Disable default exclusions.
+  # https://golangci-lint.run/usage/false-positives/#default-exclusions
+  exclude-use-default: false
+  exclude:
+  - "package-comments: .+"
+  - "ST1000: package comment should be of the form"

Makefile

@@ -15,3 +15,7 @@ schema.generate:
 	sed -e 's/CustomResourceDefinition/KRMFunctionDefinition/g' \
     -e 's|apiextensions.k8s.io/v1|config.kubernetes.io/v1alpha1|g' \
     -i  pkg/merger/schema/generators.kustomize.aabouzaid.com_mergers.yaml
+
+.PHONY: go.format
+go.format:
+	gofumpt -l -w .

main.go

@@ -3,17 +3,19 @@ package main
 import (
 	"log"
 
-	"github.com/aabouzaid/kustomize-plugin-merger/pkg/merger"
 	"sigs.k8s.io/kustomize/kyaml/fn/framework"
 	"sigs.k8s.io/kustomize/kyaml/kio"
+
+	"github.com/aabouzaid/kustomize-plugin-merger/pkg/merger"
 )
 
 func main() {
 	rlSource := &kio.ByteReadWriter{}
 	processor := &framework.VersionedAPIProcessor{FilterProvider: framework.GVKFilterMap{
 		merger.ResourceKind: {
 			merger.ResourceGroup + "/" + merger.ResourceVersion: &merger.Merger{},
-		}}}
+		},
+	}}
 	if err := framework.Execute(processor, rlSource); err != nil {
 		log.Fatal(err)
 	}

pkg/merger/doc.go

@@ -0,0 +1,2 @@
+// Package merger is the core of a Kustomize generator plugin to merge YAML files seamlessly (schemaless merge).
+package merger

pkg/merger/fn.go

@@ -1,3 +1,4 @@
+// Methods inherited by fn/framework.
 package merger
 
 import (
@@ -13,13 +14,15 @@ import (
 //go:embed "schema/generators.kustomize.aabouzaid.com_mergers.yaml"
 var mergerSchemaDefinition string
 
+// Schema returns the OpenAPI schema definition for Merger.
 func (m *Merger) Schema() (*spec.Schema, error) {
 	schema, err := framework.SchemaFromFunctionDefinition(
 		resid.NewGvk(ResourceGroup, ResourceVersion, ResourceKind),
 		mergerSchemaDefinition)
 	return schema, errors.WrapPrefixf(err, "failed to parse Merger schema")
 }
 
+// Default sets default values for Merger resources.
 func (m *Merger) Default() error {
 	for index := range m.Spec.Resources {
 		// Defaults input files.
@@ -32,16 +35,16 @@ func (m *Merger) Default() error {
 	return nil
 }
 
-func (mg *Merger) Validate() error {
-	// At the moment this only validates Merger manifest against its openAPIV3Schema.
+// Validate checks in Merger resource against its OpenAPI schema.
+func (m *Merger) Validate() error {
 	return nil
 }
 
+// Filter performs the merging of configuration files for Merger resources.
 func (m *Merger) Filter(rlItems []*yaml.RNode) ([]*yaml.RNode, error) {
 	for _, resource := range m.Spec.Resources {
 		resource.merge(resource.Input.items)
 		rlItems = append(rlItems, resource.Output.rlItems...)
 	}
-
 	return rlItems, nil
 }

pkg/merger/merge.go

@@ -1,3 +1,4 @@
+// The main logic for Merger plugin.
 package merger
 
 import (
@@ -10,6 +11,7 @@ import (
 	"sigs.k8s.io/kustomize/kyaml/yaml"
 )
 
+// setMergeStrategy sets "mergo" merging strategy, mainly for merging arrays.
 func (r *mergerResource) setMergeStrategy() {
 	switch r.Merge.Strategy {
 	case Replace:
@@ -37,6 +39,7 @@ func (r *mergerResource) setInputFilesPatch() {
 	r.Input.items = append(r.Input.items, r.Input.Files)
 }
 
+// setInputFiles determines the input file sources based on the input method (Overlay or Patch).
 func (r *mergerResource) setInputFiles() error {
 	switch r.Input.Method {
 	case Overlay:
@@ -47,6 +50,7 @@ func (r *mergerResource) setInputFiles() error {
 	return nil
 }
 
+// merge performs the actual merging of configuration files from resourceInputFiles sources.
 func (r *mergerResource) merge(rfs []resourceInputFiles) {
 	for _, rf := range rfs {
 		k := koanf.New(".")
@@ -58,10 +62,11 @@ func (r *mergerResource) merge(rfs []resourceInputFiles) {
 		for _, srcFile := range rf.Sources {
 			err := k.Load(koanfFile.Provider(srcFile), koanfYaml.Parser(),
 				koanf.WithMergeFunc(func(src, dst map[string]interface{}) error {
-					mergo.Merge(&dst, src, mergo.WithOverride, r.Merge.config)
+					if err := mergo.Merge(&dst, src, mergo.WithOverride, r.Merge.config); err != nil {
+						log.Fatalf("Error merging config: %v", err)
+					}
 					return nil
 				}))
-
 			if err != nil {
 				log.Fatalf("Error loading config: %v", err)
 			}

pkg/merger/types.go

@@ -1,3 +1,6 @@
+// The types of the merger package.
+// KubeBuilder markers are used to auto-generate OpenAPI schema for the plugin.
+//
 // +groupName=generators.kustomize.aabouzaid.com
 // +versionName=v1alpha1
 // +kubebuilder:validation:Required
@@ -10,12 +13,14 @@ import (
 	"sigs.k8s.io/kustomize/kyaml/yaml"
 )
 
+// Merger manifest configuration.
 const (
 	ResourceGroup   string = "generators.kustomize.aabouzaid.com"
 	ResourceVersion string = "v1alpha1"
 	ResourceKind    string = "Merger"
 )
 
+// Merger manifest body.
 type Merger struct {
 	metav1.TypeMeta   `json:",inline"`
 	metav1.ObjectMeta `json:"metadata"`
@@ -52,6 +57,7 @@ type resourceInputFiles struct {
 // +kubebuilder:validation:Enum=overlay;patch
 type resourceInputMethod string
 
+// Merger resource input method available options.
 const (
 	Overlay resourceInputMethod = "overlay"
 	Patch   resourceInputMethod = "patch"
@@ -71,6 +77,7 @@ type resourceInput struct {
 // +kubebuilder:validation:Enum=append;combine;replace
 type resourceMergeStrategy string
 
+// Merger resource merge strategy available options.
 // TODO: Support combine lists by named key.
 const (
 	Append  resourceMergeStrategy = "append"