Switch to go-git for a pure golang implementation

After src-d/go-git#1081 was merged,
the performance seems to be significantly better (usable).

Even if a slight bit slower, this means theres no more CGO dependency
making it much more portable.

Author: Adam Kunicki

.gitignore

@@ -19,3 +19,7 @@ beer
 
 # Project-local glide cache, RE: https://github.com/Masterminds/glide/issues/736
 .glide/
+vendor/
+
+# ignore release binaries
+dist/

.gitlab-ci.yml

@@ -1,54 +1,16 @@
-image: golang:1.11
-
-variables:
-  GOFLAGS: -mod=readonly
-  GOPATH: ${CI_PROJECT_DIR}/vendor/go
-  PKG_CONFIG_PATH: ${CI_PROJECT_DIR}/libgit2/lib/pkgconfig
-
-.modcache: &modcache
-  key: modcache
-  paths:
-    - vendor/go/pkg/mod/
-    - libgit2
-
-before_script:
-  - apt-get -qq update
-  - apt-get install -y libssh2-1-dev cmake libssl-dev zlib1g-dev libcurl4-openssl-dev
+image: docker:stable
+services:
+- docker:dind
 
 stages:
-  - dependencies
-  - test
-  - build
+- build
 
-dependencies:
-  stage: dependencies
-  before_script:
-    - apt-get -qq update
-    - apt-get install -y libssh2-1-dev cmake libssl-dev zlib1g-dev libcurl4-openssl-dev
-    - wget https://github.com/libgit2/libgit2/archive/v0.27.8.tar.gz
-    - tar xf v0.27.8.tar.gz
-    - mkdir -p ${CI_PROJECT_DIR}/libgit2
-    - pushd libgit2-0.27.8 && mkdir -p build && cd build && cmake .. -DCMAKE_INSTALL_PREFIX=${CI_PROJECT_DIR}/libgit2 && cmake --build . --target install && popd
-
-  script: go mod download
-  cache: *modcache
-
-test:
-  stage: test
-  image: golang:1.11
-  cache:
-    <<: *modcache
-    policy: pull
-  script: go test ./...
+variables:
+  GORELEASER_IMAGE: goreleaser/goreleaser:latest
+  DOCKER_REGISTRY: https://index.docker.io/v1/
 
 build:
   stage: build
-  cache:
-    <<: *modcache
-    policy: pull
-  script: go build
-  artifacts:
-    paths:
-    - beer
-    expire_in: 1 week
-
+  script:
+    - docker pull $GORELEASER_IMAGE
+    - docker run --rm --privileged -v $PWD:/go/src/github.com/kunickiaj/beer -v /var/run/docker.sock:/var/run/docker.sock -w /go/src/github.com/kunickiaj/beer -e GITHUB_TOKEN -e DOCKER_USERNAME -e DOCKER_PASSWORD -e DOCKER_REGISTRY $GORELEASER_IMAGE release --rm-dist

.goreleaser.yml

@@ -0,0 +1,31 @@
+before:
+  hooks:
+builds:
+- env:
+  - CGO_ENABLED=0
+archives:
+  - id: dist
+    replacements:
+      darwin: Darwin
+      linux: Linux
+      windows: Windows
+      amd64: x86_64
+dockers:
+-
+  goos: linux
+  goarch: amd64
+  binaries:
+  - beer
+  image_templates:
+  - 'kunickiaj/beer:{{ .Tag }}'
+  - 'kunickiaj/beer:latest'
+checksum:
+  name_template: 'checksums.txt'
+snapshot:
+  name_template: "{{ .Tag }}-next"
+changelog:
+  sort: asc
+  filters:
+    exclude:
+    - '^docs:'
+    - '^test:'

Dockerfile

@@ -0,0 +1,6 @@
+FROM scratch
+
+ADD beer /beer
+
+ENTRYPOINT [ "/beer" ]
+CMD [ "--help" ]

cmd/brew.go

@@ -20,13 +20,20 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"os/user"
+	"path"
 	"regexp"
+	"time"
+
+	"gopkg.in/src-d/go-git.v4/plumbing/object"
 
 	jira "github.com/andygrunwald/go-jira"
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
-	git "gopkg.in/libgit2/git2go.v27"
+	"gopkg.in/src-d/go-git.v4"
+	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/plumbing/format/config"
 )
 
 var brewCmd = &cobra.Command{
@@ -77,13 +84,11 @@ func brew(cmd *cobra.Command, args []string) {
 		panic(err)
 	}
 
-	repo, err := git.OpenRepositoryExtended(cwd, git.RepositoryOpenFromEnv, "")
+	repo, err := git.PlainOpenWithOptions(cwd, &git.PlainOpenOptions{DetectDotGit: true})
 	if err != nil {
 		panic(err)
 	}
 
-	defer repo.Free()
-
 	// Get user struct for logged in user
 	jiraUser, _, err := jiraClient.User.Get(username)
 	if err != nil {
@@ -231,100 +236,85 @@ func bodyToString(res *jira.Response) string {
 }
 
 func checkout(repo *git.Repository, issue *jira.Issue) error {
-	checkoutOpts := &git.CheckoutOpts{
-		Strategy: git.CheckoutSafe | git.CheckoutRecreateMissing | git.CheckoutAllowConflicts | git.CheckoutUseTheirs,
+	workTree, err := repo.Worktree()
+	if err != nil {
+		return err
 	}
 
-	// Check only for local branches
-	branch, err := repo.LookupBranch(issue.Key, git.BranchLocal)
+	branch := fmt.Sprintf("refs/heads/%s", issue.Key)
+	b := plumbing.ReferenceName(branch)
+
+	// First try to checkout branch
 	newBranch := false
-	// If it doesn't exist then create it
-	if branch == nil || err != nil {
+	err = workTree.Checkout(&git.CheckoutOptions{Create: false, Force: false, Keep: true, Branch: b})
+	if err != nil {
+		// didn't exist so try to create it
 		newBranch = true
+		err = workTree.Checkout(&git.CheckoutOptions{Create: true, Force: false, Keep: true, Branch: b})
+	}
+
+	if err != nil {
+		return err
+	}
 
-		head, err := repo.Head()
+	if newBranch {
+		commitMessage := fmt.Sprintf("%s. %s", issue.Key, issue.Fields.Summary)
+		usr, err := user.Current()
 		if err != nil {
 			return err
 		}
-
-		headCommit, err := repo.LookupCommit(head.Target())
+		gitConfig, err := os.Open(path.Join(usr.HomeDir, ".gitconfig"))
 		if err != nil {
 			return err
 		}
+		decoder := config.NewDecoder(gitConfig)
+		decodedConfig := config.New()
+		err = decoder.Decode(decodedConfig)
 
-		branch, err = repo.CreateBranch(issue.Key, headCommit, false)
 		if err != nil {
 			return err
 		}
-	}
 
-	defer branch.Free()
-
-	// Get tree for the branch
-	commit, err := repo.LookupCommit(branch.Target())
-	if err != nil {
+		userSection := decodedConfig.Section("user")
+		_, err = workTree.Commit(commitMessage, &git.CommitOptions{
+			Author: &object.Signature{
+				Name:  userSection.Option("name"),
+				Email: userSection.Option("email"),
+				When:  time.Now(),
+			},
+		})
 		return err
 	}
-
-	defer commit.Free()
-
-	tree, err := repo.LookupTree(commit.TreeId())
-	if err != nil {
-		return err
-	}
-
-	// Checkout the tree
-	err = repo.CheckoutTree(tree, checkoutOpts)
-	if err != nil {
-		return err
-	}
-
-	// Set the head to point to the new branch
-	repo.SetHead("refs/heads/" + issue.Key)
-
-	headCommit, err := repo.LookupCommit(branch.Target())
-	if err != nil {
-		return err
-	}
-
-	signature, err := repo.DefaultSignature()
-	if err != nil {
-		return err
-	}
-
-	if newBranch {
-		commitMessage := fmt.Sprintf("%s. %s", issue.Key, issue.Fields.Summary)
-		_, err = repo.CreateCommit("refs/heads/"+issue.Key, signature, signature, commitMessage, tree, headCommit)
-	}
+	
 	return nil
 }
 
 func getProjectKey(repo *git.Repository) (string, error) {
-	head, err := repo.Head()
+	ref, err := repo.Head()
 	if err != nil {
 		return "", err
 	}
 
-	commit, err := repo.LookupCommit(head.Target())
+	cIter, err := repo.Log(&git.LogOptions{From: ref.Hash()})
 	if err != nil {
 		return "", err
 	}
 
 	var depth uint
-	for depth < 5 {
+	commit, err := cIter.Next()
+	for depth < 5 && err != nil {
 		re := regexp.MustCompile("^([a-zA-Z]{3,})(-[0-9]+)")
-		message := commit.Message()
+		message := commit.Message
 		match := re.FindStringSubmatch(message)
 		if len(match) == 3 && len(match[1]) > 0 {
 			log.WithField("project_key", match[1]).Info("Inferred project key; override with --project if incorrect")
 			return match[1], nil
 		}
 		depth++
-		commit = commit.Parent(0)
+		commit, err = cIter.Next()
 	}
 
-	defer commit.Free()
-	return "", errors.New("Wasn't able to infer a project key")
+	return "", errors.New("wasn't able to infer a project key")
 }
 
 func createMetaProject(jira *jira.Client, projectKey string) (*jira.MetaProject, error) {

cmd/taste.go

@@ -22,7 +22,8 @@ import (
 
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
-	git "gopkg.in/libgit2/git2go.v27"
+	"gopkg.in/src-d/go-git.v4"
+	"gopkg.in/src-d/go-git.v4/config"
 )
 
 var tasteCmd = &cobra.Command{
@@ -57,13 +58,11 @@ func taste(cmd *cobra.Command, args []string) {
 		panic(err)
 	}
 
-	repo, err := git.OpenRepository(cwd)
+	repo, err := git.PlainOpenWithOptions(cwd, &git.PlainOpenOptions{DetectDotGit: true})
 	if err != nil {
 		panic(err)
 	}
 
-	defer repo.Free()
-
 	var ref string
 	if isWIP {
 		ref = "master%wip"
@@ -77,38 +76,13 @@ func taste(cmd *cobra.Command, args []string) {
 	}
 	log.WithField("refspec", refspec).Debug("Using refspec")
 
-	remote, err := repo.Remotes.Lookup("origin")
-	if err != nil {
-		panic(err)
-	}
-	log.WithField("remote", remote).Debug("Discovered remote")
-
-	pushOpts := &git.PushOptions{
-		RemoteCallbacks: git.RemoteCallbacks{
-			CredentialsCallback:      credentialsCallback,
-			CertificateCheckCallback: certificateCheckCallback,
-			SidebandProgressCallback: transportMessageCallback,
-		},
-	}
-	refspecs := []string{refspec}
-	err = remote.Push(refspecs, pushOpts)
+	err = repo.Push(&git.PushOptions{
+		RemoteName: "origin",
+		RefSpecs:   []config.RefSpec{config.RefSpec(refspec)},
+	})
 	if err != nil {
 		log.WithError(err).Error("Error pushing review")
 		os.Exit(1)
 	}
 	log.Info("Pushed review")
 }
-
-func credentialsCallback(url string, username string, allowedTypes git.CredType) (git.ErrorCode, *git.Cred) {
-	ret, cred := git.NewCredSshKeyFromAgent(username)
-	return git.ErrorCode(ret), &cred
-}
-
-func certificateCheckCallback(cert *git.Certificate, valid bool, hostname string) git.ErrorCode {
-	return 0
-}
-
-func transportMessageCallback(str string) git.ErrorCode {
-	fmt.Printf(str)
-	return 0
-}

go.mod

@@ -7,13 +7,11 @@ require (
 	github.com/google/go-querystring v1.0.0 // indirect
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect
 	github.com/mitchellh/go-homedir v1.1.0
-	github.com/pkg/errors v0.8.1 // indirect
 	github.com/sirupsen/logrus v1.3.0
 	github.com/spf13/afero v1.2.0 // indirect
 	github.com/spf13/cobra v0.0.3
 	github.com/spf13/viper v1.3.1
 	github.com/trivago/tgo v1.0.5 // indirect
-	golang.org/x/crypto v0.0.0-20190123085648-057139ce5d2b // indirect
-	golang.org/x/sys v0.0.0-20190124100055-b90733256f2e // indirect
-	gopkg.in/libgit2/git2go.v27 v27.0.0-20190104134018-ecaeb7a21d47
+	golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529 // indirect
+	gopkg.in/src-d/go-git.v4 v4.12.0
 )