add a tool in cmd/ to check links in go file. Currently it's only used to check the links in api descriptions (pkg/api/.../types.go).

cmd/linkcheck/links.go

@@ -0,0 +1,82 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"path/filepath"
+	"regexp"
+	"strings"
+
+	flag "github.com/spf13/pflag"
+)
+
+var (
+	httpRE *regexp.Regexp
+
+	rootDir    = flag.String("root-dir", "", "Root directory containing documents to be processed.")
+	repoRoot   = flag.String("repo-root", "", `Root directory of k8s repository.`)
+	fileSuffix = flag.String("file-suffix", "", "suffix of files to be checked")
+	prefix     = flag.String("prefix", "", "Longest common prefix of the link URL, e.g., http://release.k8s.io/HEAD/ for links in pkg/api/types.go")
+)
+
+func newWalkFunc(invalidLink *bool) filepath.WalkFunc {
+	return func(filePath string, info os.FileInfo, err error) error {
+		if !strings.HasSuffix(info.Name(), *fileSuffix) {
+			return nil
+		}
+		fileBytes, err := ioutil.ReadFile(filePath)
+		if err != nil {
+			return err
+		}
+		foundInvalid := false
+		matches := httpRE.FindAllSubmatch(fileBytes, -1)
+		for _, match := range matches {
+			//match[1] should look like docs/devel/api-conventions.md
+			if _, err := os.Stat(path.Join(*repoRoot, string(match[1]))); err != nil {
+				fmt.Fprintf(os.Stderr, "Link is not valid: %s\n", string(match[0]))
+				foundInvalid = true
+			}
+		}
+		if foundInvalid {
+			fmt.Fprintf(os.Stderr, "Found invalid links in %s\n", filePath)
+			*invalidLink = true
+		}
+		return nil
+	}
+}
+
+func main() {
+	flag.Parse()
+	httpRE = regexp.MustCompile(*prefix + `(.*\.md)`)
+
+	if *rootDir == "" || *repoRoot == "" || *prefix == "" {
+		flag.Usage()
+		os.Exit(2)
+	}
+	invalidLink := false
+	if err := filepath.Walk(*rootDir, newWalkFunc(&invalidLink)); err != nil {
+		fmt.Fprintf(os.Stderr, "Fail: %v.\n", err)
+		os.Exit(2)
+	}
+	if invalidLink {
+		os.Exit(1)
+	}
+}