Implement option to add image labels and generate automatic labels (#19)

Fixes #16

Results into labels:
![attels](/attachments/3aa6641e-fe50-4e28-be97-64c0afe2c35a)

Co-authored-by: Lauris BH <lauris@nix.lv>
Reviewed-on: https://codeberg.org/woodpecker-plugins/plugin-docker-buildx/pulls/19
Reviewed-by: 6543 <6543@obermui.de>
Co-authored-by: Lauris BH <lafriks@noreply.codeberg.org>
Co-committed-by: Lauris BH <lafriks@noreply.codeberg.org>

cmd/docker-buildx/config.go

@@ -133,6 +133,19 @@ func settingsFlags(settings *plugin.Settings) []cli.Flag {
 			Usage:       "generates tag names with the given suffix",
 			Destination: &settings.Build.TagsSuffix,
 		},
+		&cli.StringSliceFlag{
+			Name:        "labels",
+			EnvVars:     []string{"PLUGIN_LABEL", "PLUGIN_LABELS"},
+			Usage:       "sets labels to use for the image",
+			Destination: &settings.Build.Labels,
+		},
+		&cli.BoolFlag{
+			Name:        "labels.auto",
+			EnvVars:     []string{"PLUGIN_DEFAULT_LABELS", "PLUGIN_AUTO_LABEL"},
+			Usage:       "generates labels automatically based on git repository info",
+			Value:       true,
+			Destination: &settings.Build.LabelsAuto,
+		},
 		&cli.StringSliceFlag{
 			Name:        "args",
 			EnvVars:     []string{"PLUGIN_BUILD_ARGS"},

docs.md

@@ -98,6 +98,8 @@ It will automatically generate buildkit configuration to use custom CA certifica
 | `context`                 | `.`               | sets the path of the build context to use
 | `default_tags`/`auto_tag` | `false`           | generates tag names automatically based on git branch and git tag
 | `default_suffix"`/`auto_tag_suffix`| *none*   | generates tag names with the given suffix
+| `label`/`labels`          | *none*            | sets labels to use for the image in format `<name>=<value>`
+| `default_labels`/`auto_labels` | `true`       | sets docker image labels based on git information
 | `build_args`              | *none*            | sets custom build arguments for the build
 | `build_args_from_env`     | *none*            | forwards environment variables as custom arguments to the build
 | `quiet`                   | `false`           | enables suppression of the build output

plugin/docker.go

@@ -126,6 +126,10 @@ func commandBuild(build Build, dryrun bool) *exec.Cmd {
 		args = append(args, "-t", fmt.Sprintf("%s:%s", build.Repo, arg))
 	}
 
+	for _, l := range build.Labels.Value() {
+		args = append(args, "--label", l)
+	}
+
 	return exec.Command(dockerExe, args...)
 }
 

plugin/impl.go

@@ -49,6 +49,8 @@ type Build struct {
 	TagsAuto   bool            // Docker build auto tag
 	TagsSuffix string          // Docker build tags with suffix
 	Tags       cli.StringSlice // Docker build tags
+	LabelsAuto bool            // Docker build auto labels
+	Labels     cli.StringSlice // Docker build labels
 	Platforms  cli.StringSlice // Docker build target platforms
 	Args       cli.StringSlice // Docker build args
 	ArgsEnv    cli.StringSlice // Docker build args from env
@@ -98,6 +100,9 @@ func (p *Plugin) Validate() error {
 			return nil
 		}
 	}
+	if p.settings.Build.LabelsAuto {
+		p.settings.Build.Labels = *cli.NewStringSlice(p.Labels()...)
+	}
 
 	return nil
 }

plugin/labels.go

@@ -0,0 +1,32 @@
+package plugin
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/coreos/go-semver/semver"
+)
+
+// Labels returns list of labels to use for image
+func (p *Plugin) Labels() []string {
+	l := p.settings.Build.Labels.Value()
+	// As described in https://github.com/opencontainers/image-spec/blob/main/annotations.md
+	l = append(l, fmt.Sprintf("org.opencontainers.image.created=%s", time.Now().UTC().Format(time.RFC3339)))
+	if p.settings.Build.Remote != "" {
+		l = append(l, fmt.Sprintf("org.opencontainers.image.source=%s", p.settings.Build.Remote))
+	}
+	if p.pipeline.Repo.Link != "" {
+		l = append(l, fmt.Sprintf("org.opencontainers.image.url=%s", p.pipeline.Repo.Link))
+	}
+	if p.pipeline.Commit.SHA != "" {
+		l = append(l, fmt.Sprintf("org.opencontainers.image.revision=%s", p.pipeline.Commit.SHA))
+	}
+	if p.settings.Build.Ref != "" && strings.HasPrefix(p.settings.Build.Ref, "refs/tags/") {
+		v, err := semver.NewVersion(strings.TrimPrefix(p.settings.Build.Ref[10:], "v"))
+		if err == nil && v != nil {
+			l = append(l, fmt.Sprintf("org.opencontainers.image.version=%s", v.String()))
+		}
+	}
+	return l
+}