Move git code to its own pkg.

pkg/git/cloner.go

@@ -0,0 +1,210 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+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 git
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os/exec"
+	"path/filepath"
+	"regexp"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+// Cloner is a function that can clone a git repo.
+type Cloner func(url string) (
+	// Directory where the repo is cloned to.
+	checkoutDir string,
+	// Relative path in the checkoutDir to location
+	// of kustomization file.
+	pathInCoDir string,
+	// Any error encountered when cloning.
+	err error)
+
+// IsRepoUrl checks if a string is likely a github repo Url.
+func IsRepoUrl(arg string) bool {
+	arg = strings.ToLower(arg)
+	return !filepath.IsAbs(arg) &&
+		(strings.HasPrefix(arg, "git::") ||
+			strings.HasPrefix(arg, "gh:") ||
+			strings.HasPrefix(arg, "ssh:") ||
+			strings.HasPrefix(arg, "github.com") ||
+			strings.HasPrefix(arg, "git@") ||
+			strings.Index(arg, "github.com/") > -1 ||
+			isAzureHost(arg) || isAWSHost(arg))
+}
+
+func makeTmpDir() (string, error) {
+	return ioutil.TempDir("", "kustomize-")
+}
+
+func ClonerUsingGitExec(spec string) (
+	checkoutDir string, pathInCoDir string, err error) {
+	gitProgram, err := exec.LookPath("git")
+	if err != nil {
+		return "", "", errors.Wrap(err, "no 'git' program on path")
+	}
+	checkoutDir, err = makeTmpDir()
+	if err != nil {
+		return
+	}
+	repo, pathInCoDir, gitRef, err := parseUrl(spec)
+	if err != nil {
+		return
+	}
+	cmd := exec.Command(
+		gitProgram,
+		"clone",
+		repo,
+		checkoutDir)
+	var out bytes.Buffer
+	cmd.Stdout = &out
+	err = cmd.Run()
+	if err != nil {
+		return "", "",
+			errors.Wrapf(err, "trouble cloning %s", spec)
+	}
+	if gitRef == "" {
+		return
+	}
+	cmd = exec.Command(gitProgram, "checkout", gitRef)
+	cmd.Dir = checkoutDir
+	err = cmd.Run()
+	if err != nil {
+		return "", "",
+			errors.Wrapf(err, "trouble checking out href %s", gitRef)
+	}
+	return checkoutDir, pathInCoDir, nil
+}
+
+func parseUrl(n string) (
+	repo string, path string, gitRef string, err error) {
+	host, repo, path, gitRef, err := parseGithubUrl(n)
+	if err != nil {
+		return
+	}
+	if isAzureHost(host) || isAWSHost(host) {
+		repo = host + repo
+		return
+	}
+	repo = host + repo + ".git"
+	return
+}
+
+const (
+	refQuery  = "?ref="
+	gitSuffix = ".git"
+)
+
+// From strings like git@github.com:someOrg/someRepo.git or
+// https://github.com/someOrg/someRepo?ref=someHash, extract
+// the parts.
+func parseGithubUrl(n string) (
+	host string, repo string, path string, gitRef string, err error) {
+	host, n = parseHostSpec(n)
+	host = normalizeGitHostSpec(host)
+
+	if strings.HasSuffix(n, gitSuffix) {
+		repo = n[0 : len(n)-len(gitSuffix)]
+		return
+	}
+	if strings.Contains(n, gitSuffix) {
+		index := strings.Index(n, gitSuffix)
+		repo = n[0:index]
+		n = n[index+len(gitSuffix):]
+		path, gitRef = peelQuery(n)
+		return
+	}
+	i := strings.Index(n, "/")
+	if i < 1 {
+		return "", "", "", "", errors.New("no separator")
+	}
+	j := strings.Index(n[i+1:], "/")
+	if j >= 0 {
+		j += i + 1
+		repo = n[:j]
+		path, gitRef = peelQuery(n[j+1:])
+	} else {
+		path = ""
+		repo, gitRef = peelQuery(n)
+	}
+	return
+}
+
+func peelQuery(arg string) (string, string) {
+	j := strings.Index(arg, refQuery)
+	if j >= 0 {
+		return arg[:j], arg[j+len(refQuery):]
+	}
+	return arg, ""
+}
+
+func parseHostSpec(n string) (string, string) {
+	var host string
+	for _, p := range []string{
+		// Order matters here.
+		"git::", "gh:", "ssh://", "https://", "http://",
+		"git@", "github.com:", "github.com/"} {
+		if strings.ToLower(n[:len(p)]) == p {
+			n = n[len(p):]
+			host = host + p
+		}
+	}
+
+	// If host is a http(s) or ssh URL, grab the domain part.
+	for _, p := range []string{
+		"ssh://", "https://", "http://"} {
+		if strings.HasSuffix(strings.ToLower(host), p) {
+			index := regexp.MustCompile("^(.*?)/").FindStringIndex(n)
+			if len(index) > 0 {
+				host = host + n[0:index[len(index)-1]]
+				n = n[index[len(index)-1]:]
+			}
+		}
+	}
+	return host, n
+}
+
+func normalizeGitHostSpec(host string) string {
+	s := strings.ToLower(host)
+	if strings.Contains(s, "github.com") {
+		if strings.Contains(s, "git@") || strings.Contains(s, "ssh:") {
+			host = "git@github.com:"
+		} else {
+			host = "https://github.com/"
+		}
+	}
+	if strings.HasPrefix(s, "git::") {
+		host = strings.TrimLeft(s, "git::")
+	}
+	return host
+}
+
+// The format of Azure repo URL is documented
+// https://docs.microsoft.com/en-us/azure/devops/repos/git/clone?view=vsts&tabs=visual-studio#clone_url
+func isAzureHost(host string) bool {
+	return strings.Contains(host, "dev.azure.com") ||
+		strings.Contains(host, "visualstudio.com")
+}
+
+// The format of AWS repo URL is documented
+// https://docs.aws.amazon.com/codecommit/latest/userguide/regions.html
+func isAWSHost(host string) bool {
+	return strings.Contains(host, "amazonaws.com")
+}