dockerfile: generate lint rules documentation

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>

Makefile

@@ -113,6 +113,10 @@ doctoc:
 docs:
 	$(BUILDX_CMD) bake docs
 
+.PHONY: docs-dockerfile
+docs-dockerfile:
+	$(BUILDX_CMD) bake docs-dockerfile
+
 .PHONY: mod-outdated
 mod-outdated:
 	$(BUILDX_CMD) bake mod-outdated

docker-bake.hcl

@@ -126,7 +126,7 @@ target "integration-tests" {
 }
 
 group "validate" {
-  targets = ["lint", "validate-vendor", "validate-doctoc", "validate-generated-files", "validate-archutil", "validate-shfmt", "validate-docs"]
+  targets = ["lint", "validate-vendor", "validate-doctoc", "validate-generated-files", "validate-archutil", "validate-shfmt", "validate-docs", "validate-docs-dockerfile"]
 }
 
 target "lint" {
@@ -211,6 +211,13 @@ target "validate-docs" {
   output = ["type=cacheonly"]
 }
 
+target "validate-docs-dockerfile" {
+  inherits = ["_common"]
+  dockerfile = "./hack/dockerfiles/docs-dockerfile.Dockerfile"
+  target = "validate"
+  output = ["type=cacheonly"]
+}
+
 target "vendor" {
   inherits = ["_common"]
   dockerfile = "./hack/dockerfiles/vendor.Dockerfile"
@@ -260,6 +267,13 @@ target "docs" {
   output = ["./docs"]
 }
 
+target "docs-dockerfile" {
+  inherits = ["_common"]
+  dockerfile = "./hack/dockerfiles/docs-dockerfile.Dockerfile"
+  target = "update"
+  output = ["./frontend/dockerfile/docs/rules"]
+}
+
 target "mod-outdated" {
   inherits = ["_common"]
   dockerfile = "./hack/dockerfiles/vendor.Dockerfile"

frontend/dockerfile/docs/rules/file-consistent-command-casing.md

@@ -0,0 +1,55 @@
+---
+title: FileConsistentCommandCasing
+description: All commands within the Dockerfile should use the same casing (either upper or lower)
+---
+
+Example warning:
+
+```text
+Command 'foo' should match the case of the command majority (uppercase)
+```
+
+Instructions within a Dockerfile should have consistent casing through out the
+entire files. Instructions are not case-sensitive, but the convention is to use
+uppercase for instruction keywords to make it easier to distinguish keywords
+from arguments.
+
+Whether you prefer instructions to be uppercase or lowercase, you should make
+sure you use consistent casing to help improve readability of the Dockerfile.
+
+## Examples
+
+❌ Bad: mixing uppercase and lowercase
+
+```dockerfile
+FROM alpine:latest AS builder
+run apk --no-cache add build-base
+
+FROM builder AS build1
+copy source1.cpp source.cpp
+```
+
+✅ Good: all uppercase
+
+```dockerfile
+FROM alpine:latest AS builder
+RUN apk --no-cache add build-base
+
+FROM builder AS build1
+COPY source1.cpp source.cpp
+```
+
+✅ Good: all lowercase
+
+```dockerfile
+from alpine:latest as builder
+run apk --no-cache add build-base
+
+from builder as build1
+copy source1.cpp source.cpp
+```
+
+## Related errors
+
+- [`FromAsCasing`](./from-as-casing.md)
+

frontend/dockerfile/linter/docs/FileConsistentCommandCasing.md

@@ -0,0 +1,49 @@
+Example warning:
+
+```text
+Command 'foo' should match the case of the command majority (uppercase)
+```
+
+Instructions within a Dockerfile should have consistent casing through out the
+entire files. Instructions are not case-sensitive, but the convention is to use
+uppercase for instruction keywords to make it easier to distinguish keywords
+from arguments.
+
+Whether you prefer instructions to be uppercase or lowercase, you should make
+sure you use consistent casing to help improve readability of the Dockerfile.
+
+## Examples
+
+❌ Bad: mixing uppercase and lowercase
+
+```dockerfile
+FROM alpine:latest AS builder
+run apk --no-cache add build-base
+
+FROM builder AS build1
+copy source1.cpp source.cpp
+```
+
+✅ Good: all uppercase
+
+```dockerfile
+FROM alpine:latest AS builder
+RUN apk --no-cache add build-base
+
+FROM builder AS build1
+COPY source1.cpp source.cpp
+```
+
+✅ Good: all lowercase
+
+```dockerfile
+from alpine:latest as builder
+run apk --no-cache add build-base
+
+from builder as build1
+copy source1.cpp source.cpp
+```
+
+## Related errors
+
+- [`FromAsCasing`](./from-as-casing.md)

frontend/dockerfile/linter/generate.go

@@ -0,0 +1,133 @@
+//go:build ignore
+// +build ignore
+
+package main
+
+import (
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"log"
+	"os"
+	"path"
+	"regexp"
+	"strings"
+	"text/template"
+
+	"github.com/pkg/errors"
+)
+
+type Rule struct {
+	Name        string
+	Description string
+}
+
+const tmplStr = `---
+title: {{.Rule.Name}}
+description: {{.Rule.Description}}
+---
+
+{{.Content}}
+`
+
+var destDir string
+
+func main() {
+	if len(os.Args) < 2 {
+		panic("Please provide a destination directory")
+	}
+	destDir = os.Args[1]
+	log.Printf("Destination directory: %s\n", destDir)
+	if err := run(destDir); err != nil {
+		panic(err)
+	}
+}
+
+func run(destDir string) error {
+	if err := os.MkdirAll(destDir, 0700); err != nil {
+		return err
+	}
+	rules, err := listRules()
+	if err != nil {
+		return err
+	}
+	tmpl, err := template.New("rule").Parse(tmplStr)
+	if err != nil {
+		return err
+	}
+	for _, rule := range rules {
+		if ok, err := genRuleDoc(rule, tmpl); err != nil {
+			return errors.Wrapf(err, "Error generating docs for %s", rule.Name)
+		} else if ok {
+			log.Printf("Docs generated for %s\n", rule.Name)
+		}
+	}
+	return nil
+}
+
+func genRuleDoc(rule Rule, tmpl *template.Template) (bool, error) {
+	mdfilename := fmt.Sprintf("docs/%s.md", rule.Name)
+	content, err := os.ReadFile(mdfilename)
+	if err != nil {
+		return false, err
+	}
+	outputfile, err := os.Create(path.Join(destDir, fmt.Sprintf("%s.md", camelToKebab(rule.Name))))
+	if err != nil {
+		return false, err
+	}
+	defer outputfile.Close()
+	if err = tmpl.Execute(outputfile, struct {
+		Rule    Rule
+		Content string
+	}{
+		Rule:    rule,
+		Content: string(content),
+	}); err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+func listRules() ([]Rule, error) {
+	fset := token.NewFileSet()
+	node, err := parser.ParseFile(fset, "ruleset.go", nil, parser.ParseComments)
+	if err != nil {
+		return nil, err
+	}
+	var rules []Rule
+	ast.Inspect(node, func(n ast.Node) bool {
+		switch x := n.(type) {
+		case *ast.GenDecl:
+			for _, spec := range x.Specs {
+				if vSpec, ok := spec.(*ast.ValueSpec); ok {
+					rule := Rule{}
+					if cl, ok := vSpec.Values[0].(*ast.CompositeLit); ok {
+						for _, elt := range cl.Elts {
+							if kv, ok := elt.(*ast.KeyValueExpr); ok {
+								switch kv.Key.(*ast.Ident).Name {
+								case "Name":
+									if basicLit, ok := kv.Value.(*ast.BasicLit); ok {
+										rule.Name = strings.Trim(basicLit.Value, `"`)
+									}
+								case "Description":
+									if basicLit, ok := kv.Value.(*ast.BasicLit); ok {
+										rule.Description = strings.Trim(basicLit.Value, `"`)
+									}
+								}
+							}
+						}
+					}
+					rules = append(rules, rule)
+				}
+			}
+		}
+		return true
+	})
+	return rules, nil
+}
+
+func camelToKebab(s string) string {
+	var re = regexp.MustCompile(`([a-z])([A-Z])`)
+	return strings.ToLower(re.ReplaceAllString(s, `${1}-${2}`))
+}

hack/dockerfiles/docs-dockerfile.Dockerfile

@@ -0,0 +1,46 @@
+# syntax=docker/dockerfile:1
+
+ARG GO_VERSION=1.21
+ARG ALPINE_VERSION=3.20
+
+FROM golang:${GO_VERSION}-alpine${ALPINE_VERSION} AS golatest
+
+FROM golatest AS docsgen
+WORKDIR /src
+ENV CGO_ENABLED=0
+RUN --mount=target=. \
+  --mount=target=/root/.cache,type=cache \
+  --mount=target=/go/pkg/mod,type=cache \
+  go build -mod=vendor -o /out/docsgen ./frontend/dockerfile/linter/generate.go
+
+FROM alpine AS gen
+RUN apk add --no-cache rsync git
+WORKDIR /src
+COPY --from=docsgen /out/docsgen /usr/bin
+RUN --mount=target=/context \
+  --mount=target=.,type=tmpfs <<EOT
+set -ex
+rsync -a /context/. .
+cd frontend/dockerfile/linter
+docsgen ./dist
+mkdir /out
+cp -r dist/* /out
+EOT
+
+FROM scratch AS update
+COPY --from=gen /out /
+
+FROM gen AS validate
+RUN --mount=target=/context \
+  --mount=target=.,type=tmpfs <<EOT
+set -e
+rsync -a /context/. .
+git add -A
+rm -rf frontend/dockerfile/docs/rules/*
+cp -rf /out/* ./frontend/dockerfile/docs/rules/
+if [ -n "$(git status --porcelain -- frontend/dockerfile/docs/rules/)" ]; then
+  echo >&2 'ERROR: Dockerfile docs result differs. Please update with "make docs-dockerfile"'
+  git status --porcelain -- frontend/dockerfile/docs/rules/
+  exit 1
+fi
+EOT