build: set provenance vcs details

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

util/gitutil/gitutil.go

@@ -0,0 +1,123 @@
+package gitutil
+
+import (
+	"bytes"
+	"context"
+	"os/exec"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+// Git represents an active git object
+type Git struct {
+	ctx context.Context
+	wd  string
+}
+
+// Option provides a variadic option for configuring the git client.
+type Option func(b *Git)
+
+// WithContext sets context.
+func WithContext(ctx context.Context) Option {
+	return func(b *Git) {
+		b.ctx = ctx
+	}
+}
+
+// WithWorkingDir sets working directory.
+func WithWorkingDir(wd string) Option {
+	return func(b *Git) {
+		b.wd = wd
+	}
+}
+
+// New initializes a new git client
+func New(opts ...Option) *Git {
+	c := &Git{
+		ctx: context.Background(),
+	}
+	for _, opt := range opts {
+		opt(c)
+	}
+	return c
+}
+
+func (c *Git) IsInsideWorkTree() bool {
+	out, err := c.clean(c.run("rev-parse", "--is-inside-work-tree"))
+	return out == "true" && err == nil
+}
+
+func (c *Git) IsDirty() bool {
+	out, err := c.run("status", "--porcelain", "--ignored")
+	return strings.TrimSpace(out) != "" || err != nil
+}
+
+func (c *Git) RootDir() (string, error) {
+	return c.clean(c.run("rev-parse", "--show-toplevel"))
+}
+
+func (c *Git) RemoteURL() (string, error) {
+	return c.clean(c.run("ls-remote", "--get-url"))
+}
+
+func (c *Git) FullCommit() (string, error) {
+	return c.clean(c.run("show", "--format=%H", "HEAD", "--quiet"))
+}
+
+func (c *Git) ShortCommit() (string, error) {
+	return c.clean(c.run("show", "--format=%h", "HEAD", "--quiet"))
+}
+
+func (c *Git) Tag() (string, error) {
+	var tag string
+	var err error
+	for _, fn := range []func() (string, error){
+		func() (string, error) {
+			return c.clean(c.run("tag", "--points-at", "HEAD", "--sort", "-version:creatordate"))
+		},
+		func() (string, error) {
+			return c.clean(c.run("describe", "--tags", "--abbrev=0"))
+		},
+	} {
+		tag, err = fn()
+		if tag != "" || err != nil {
+			return tag, err
+		}
+	}
+	return tag, err
+}
+
+func (c *Git) run(args ...string) (string, error) {
+	if _, err := exec.LookPath("git"); err != nil {
+		return "", errors.New("git not present in PATH")
+	}
+
+	var extraArgs = []string{
+		"-c", "log.showSignature=false",
+	}
+
+	args = append(extraArgs, args...)
+	cmd := exec.Command("git", args...)
+	if c.wd != "" {
+		cmd.Dir = c.wd
+	}
+
+	stdout := bytes.Buffer{}
+	stderr := bytes.Buffer{}
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	if err := cmd.Run(); err != nil {
+		return "", errors.New(stderr.String())
+	}
+	return stdout.String(), nil
+}
+
+func (c *Git) clean(out string, err error) (string, error) {
+	out = strings.ReplaceAll(strings.Split(out, "\n")[0], "'", "")
+	if err != nil {
+		err = errors.New(strings.TrimSuffix(err.Error(), "\n"))
+	}
+	return out, err
+}