Fix manifest yml (#45)

From de43f3afb6, both the code and the
commit message used singular form of expand_tag, but the example in the
README used the plural form of expand_tags. Based on that I assume the
singular form was the intention and the plural form in the README was a
typo (the plural form does not work because the code only checks for the
singular form env var).

.drone.yml

@@ -4,7 +4,7 @@ name: default
 
 steps:
 - name: build
-  image: golang
+  image: golang:1.17.7
   commands:
   - go test ./...
   - sh scripts/build.sh
@@ -60,6 +60,56 @@ steps:
       exclude:
       - pull_request
 
+- name: docker-kaniko-v1-8
+  image: plugins/docker
+  settings:
+    repo: plugins/kaniko
+    auto_tag: true
+    auto_tag_suffix: linux-amd64-kaniko1.8.0
+    daemon_off: false
+    dockerfile: docker/docker/Dockerfile.linux.amd64.kaniko1.8.0
+    username:
+      from_secret: docker_username
+    password:
+      from_secret: docker_password
+  when:
+    event:
+      exclude:
+      - pull_request
+
+- name: gcr-kaniko-v1-8
+  image: plugins/docker
+  settings:
+    repo: plugins/kaniko-gcr
+    auto_tag: true
+    auto_tag_suffix: linux-amd64-kaniko1.8.0
+    daemon_off: false
+    dockerfile: docker/gcr/Dockerfile.linux.amd64.kaniko1.8.0
+    username:
+      from_secret: docker_username
+    password:
+      from_secret: docker_password
+  when:
+    event:
+      exclude:
+      - pull_request
+
+- name: ecr-kaniko-v1-8
+  image: plugins/docker
+  settings:
+    repo: plugins/kaniko-ecr
+    auto_tag: true
+    auto_tag_suffix: linux-amd64-kaniko1.8.0
+    daemon_off: false
+    dockerfile: docker/ecr/Dockerfile.linux.amd64.kaniko1.8.0
+    username:
+      from_secret: docker_username
+    password:
+      from_secret: docker_password
+  when:
+    event:
+      exclude:
+      - pull_request
 ---
 kind: pipeline
 type: docker
@@ -112,4 +162,58 @@ trigger:
   - "refs/tags/**"
 
 depends_on:
-- default
+- default
+
+---
+kind: pipeline
+type: docker
+name: notifications-docker-kaniko1-8
+
+platform:
+  os: linux
+  arch: amd64
+
+steps:
+- name: manifest-docker
+  pull: always
+  image: plugins/manifest
+  settings:
+    auto_tag: true
+    ignore_missing: true
+    password:
+      from_secret: docker_password
+    spec: docker/docker/manifest-kaniko1.8.0.tmpl
+    username:
+      from_secret: docker_username
+
+- name: manifest-gcr
+  pull: always
+  image: plugins/manifest
+  settings:
+    auto_tag: true
+    ignore_missing: true
+    password:
+      from_secret: docker_password
+    spec: docker/gcr/manifest-kaniko1.8.0.tmpl
+    username:
+      from_secret: docker_username
+
+- name: manifest-ecr
+  pull: always
+  image: plugins/manifest
+  settings:
+    auto_tag: true
+    ignore_missing: true
+    password:
+      from_secret: docker_password
+    spec: docker/ecr/manifest-kaniko1.8.0.tmpl
+    username:
+      from_secret: docker_username
+
+trigger:
+  ref:
+  - refs/heads/main
+  - "refs/tags/**"
+
+depends_on:
+- default

README.md

@@ -39,6 +39,7 @@ docker build \
 ```
 
 ## Usage
+### Manual Tagging
 
 ```console
 docker run --rm \
@@ -51,3 +52,79 @@ docker run --rm \
     -w /drone \
     plugins/kaniko:linux-amd64
 ```
+
+With expanded tagging enabled, semantic versions can be passed to PLUGIN_TAGS directly for expansion.
+
+**Note**: this feature only works for build labels. Artifact labels are not supported.
+
+```console
+docker run --rm \
+    -e PLUGIN_TAGS=v1.2.3,latest \
+    -e PLUGIN_EXPAND_TAG=true \
+    -v $(pwd):/drone \
+    -w /drone \
+    plugins/kaniko:linux-amd64
+```
+would both be equivalent to
+
+```
+PLUGIN_TAGS=1,1.2,1.2.3,latest
+```
+
+This allows for passing `$DRONE_TAG` directly as a tag for repos that use [semver](https://semver.org) tags.
+
+To avoid confusion between repo tags and image tags, `PLUGIN_EXPAND_TAG` also recognizes a semantic version
+without the `v` prefix.  As such, the following is also equivalent to the above:
+
+```console
+docker run --rm \
+    -e PLUGIN_TAGS=1.2.3,latest \
+    -e PLUGIN_EXPAND_TAG=true \
+    -v $(pwd):/drone \
+    -w /drone \
+    plugins/kaniko:linux-amd64
+```
+
+### Auto Tagging
+The [auto tag feature](https://plugins.drone.io/drone-plugins/drone-docker) of docker plugin is also supported.
+
+When auto tagging is enabled, if any of the case is matched below, a docker build will be pushed with auto generated tags. Otherwise the docker build will be skipped.
+
+**Note**: this feature only works for build labels. Artifact labels are not supported.
+
+#### Git Tag Push:
+
+```console
+docker run --rm \
+    -e DRONE_COMMIT_REF=refs/tags/v1.2.3 \
+    -e PLUGIN_REPO=foo/bar \
+    -e PLUGIN_USERNAME=foo \
+    -e PLUGIN_PASSWORD=bar \
+    -e PLUGIN_AUTO_TAG=true \
+    -v $(pwd):/drone \
+    -w /drone \
+    plugins/kaniko:linux-amd64
+```
+
+Tags to push:
+- 1.2.3
+- 1.2
+- 1
+
+#### Git Commit Push in default branch:
+
+```console
+docker run --rm \
+    -e DRONE_COMMIT_REF=refs/heads/master \
+    -e DRONE_REPO_BRANCH=main \
+    -e PLUGIN_REPO=foo/bar \
+    -e PLUGIN_USERNAME=foo \
+    -e PLUGIN_PASSWORD=bar \
+    -e PLUGIN_AUTO_TAG=true \
+    -v $(pwd):/drone \
+    -w /drone \
+    plugins/kaniko:linux-amd64
+```
+
+Tags to push:
+- latest

cmd/kaniko-docker/main.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"strings"
 
 	"github.com/joho/godotenv"
 	"github.com/pkg/errors"
@@ -12,7 +13,7 @@ import (
 	"github.com/urfave/cli"
 
 	kaniko "github.com/drone/drone-kaniko"
-	"github.com/drone/drone-kaniko/cmd/artifact"
+	"github.com/drone/drone-kaniko/pkg/artifact"
 )
 
 const (
@@ -20,8 +21,9 @@ const (
 	dockerPath       string = "/kaniko/.docker"
 	dockerConfigPath string = "/kaniko/.docker/config.json"
 
-	v1Registry string = "https://index.docker.io/v1/" // Default registry
-	v2Registry string = "https://index.docker.io/v2/" // v2 registry is not supported
+	v1RegistryURL    string = "https://index.docker.io/v1/" // Default registry
+	v2RegistryURL    string = "https://index.docker.io/v2/" // v2 registry is not supported
+	v2HubRegistryURL string = "https://registry.hub.docker.com/v2/"
 
 	defaultDigestFile string = "/kaniko/digest-file"
 )
@@ -56,6 +58,16 @@ func main() {
 			Value:  ".",
 			EnvVar: "PLUGIN_CONTEXT",
 		},
+		cli.StringFlag{
+			Name:   "drone-commit-ref",
+			Usage:  "git commit ref passed by Drone",
+			EnvVar: "DRONE_COMMIT_REF",
+		},
+		cli.StringFlag{
+			Name:   "drone-repo-branch",
+			Usage:  "git repository default branch passed by Drone",
+			EnvVar: "DRONE_REPO_BRANCH",
+		},
 		cli.StringSliceFlag{
 			Name:     "tags",
 			Usage:    "build tags",
@@ -63,6 +75,21 @@ func main() {
 			EnvVar:   "PLUGIN_TAGS",
 			FilePath: ".tags",
 		},
+		cli.BoolFlag{
+			Name:   "expand-tag",
+			Usage:  "enable for semver tagging",
+			EnvVar: "PLUGIN_EXPAND_TAG",
+		},
+		cli.BoolFlag{
+			Name:   "auto-tag",
+			Usage:  "enable auto generation of build tags",
+			EnvVar: "PLUGIN_AUTO_TAG",
+		},
+		cli.StringFlag{
+			Name:   "auto-tag-suffix",
+			Usage:  "the suffix of auto build tags",
+			EnvVar: "PLUGIN_AUTO_TAG_SUFFIX",
+		},
 		cli.StringSliceFlag{
 			Name:   "args",
 			Usage:  "build args",
@@ -86,9 +113,14 @@ func main() {
 		cli.StringFlag{
 			Name:   "registry",
 			Usage:  "docker registry",
-			Value:  v1Registry,
+			Value:  v1RegistryURL,
 			EnvVar: "PLUGIN_REGISTRY",
 		},
+		cli.StringSliceFlag{
+			Name:   "registry-mirrors",
+			Usage:  "docker registry mirrors",
+			EnvVar: "PLUGIN_REGISTRY_MIRRORS",
+		},
 		cli.StringFlag{
 			Name:   "username",
 			Usage:  "docker username",
@@ -139,6 +171,11 @@ func main() {
 			Usage:  "Set this flag with value as oneof <panic|fatal|error|warn|info|debug|trace> to set the logging level for kaniko. Defaults to info.",
 			EnvVar: "PLUGIN_VERBOSITY",
 		},
+		cli.StringFlag{
+			Name:   "platform",
+			Usage:  "Allows to build with another default platform than the host, similarly to docker build --platform",
+			EnvVar: "PLUGIN_PLATFORM",
+		},
 	}
 
 	if err := app.Run(os.Args); err != nil {
@@ -159,25 +196,32 @@ func run(c *cli.Context) error {
 
 	plugin := kaniko.Plugin{
 		Build: kaniko.Build{
-			Dockerfile:    c.String("dockerfile"),
-			Context:       c.String("context"),
-			Tags:          c.StringSlice("tags"),
-			Args:          c.StringSlice("args"),
-			Target:        c.String("target"),
-			Repo:          c.String("repo"),
-			Labels:        c.StringSlice("custom-labels"),
-			SkipTlsVerify: c.Bool("skip-tls-verify"),
-			SnapshotMode:  c.String("snapshot-mode"),
-			EnableCache:   c.Bool("enable-cache"),
-			CacheRepo:     c.String("cache-repo"),
-			CacheTTL:      c.Int("cache-ttl"),
-			DigestFile:    defaultDigestFile,
-			NoPush:        noPush,
-			Verbosity:     c.String("verbosity"),
+			DroneCommitRef:  c.String("drone-commit-ref"),
+			DroneRepoBranch: c.String("drone-repo-branch"),
+			Dockerfile:      c.String("dockerfile"),
+			Context:         c.String("context"),
+			Tags:            c.StringSlice("tags"),
+			AutoTag:         c.Bool("auto-tag"),
+			AutoTagSuffix:   c.String("auto-tag-suffix"),
+			ExpandTag:       c.Bool("expand-tag"),
+			Args:            c.StringSlice("args"),
+			Target:          c.String("target"),
+			Repo:            buildRepo(c.String("registry"), c.String("repo")),
+			Mirrors:         c.StringSlice("registry-mirrors"),
+			Labels:          c.StringSlice("custom-labels"),
+			SkipTlsVerify:   c.Bool("skip-tls-verify"),
+			SnapshotMode:    c.String("snapshot-mode"),
+			EnableCache:     c.Bool("enable-cache"),
+			CacheRepo:       buildRepo(c.String("registry"), c.String("cache-repo")),
+			CacheTTL:        c.Int("cache-ttl"),
+			DigestFile:      defaultDigestFile,
+			NoPush:          noPush,
+			Verbosity:       c.String("verbosity"),
+			Platform:        c.String("platform"),
 		},
 		Artifact: kaniko.Artifact{
 			Tags:         c.StringSlice("tags"),
-			Repo:         c.String("repo"),
+			Repo:         buildRepo(c.String("registry"), c.String("repo")),
 			Registry:     c.String("registry"),
 			ArtifactFile: c.String("artifact-file"),
 			RegistryType: artifact.Docker,
@@ -198,10 +242,10 @@ func createDockerCfgFile(username, password, registry string) error {
 		return fmt.Errorf("Registry must be specified")
 	}
 
-	if registry == v2Registry {
+	if registry == v2RegistryURL || registry == v2HubRegistryURL {
 		fmt.Println("Docker v2 registry is not supported in kaniko. Refer issue: https://github.com/GoogleContainerTools/kaniko/issues/1209")
-		fmt.Printf("Using v1 registry instead: %s\n", v1Registry)
-		registry = v1Registry
+		fmt.Printf("Using v1 registry instead: %s\n", v1RegistryURL)
+		registry = v1RegistryURL
 	}
 
 	err := os.MkdirAll(dockerPath, 0600)
@@ -218,3 +262,19 @@ func createDockerCfgFile(username, password, registry string) error {
 	}
 	return nil
 }
+
+func buildRepo(registry, repo string) string {
+	if registry == "" {
+		// No custom registry, just return the repo name
+		return repo
+	}
+	// Trim off trailing slash to prevent double slash when combining with repo
+	registry = strings.TrimSuffix(registry, "/")
+	if strings.HasPrefix(repo, registry+"/") {
+		// Repo already includes the registry prefix
+		// For backward compatibility, we won't add the prefix again.
+		return repo
+	}
+	// Prefix the repo with the registry
+	return registry + "/" + repo
+}

cmd/kaniko-docker/main_test.go

@@ -0,0 +1,37 @@
+package main
+
+import "testing"
+
+func Test_buildRepo(t *testing.T) {
+	tests := []struct {
+		name     string
+		registry string
+		repo     string
+		want     string
+	}{
+		{
+			name: "dockerhub",
+			repo: "golang",
+			want: "golang",
+		},
+		{
+			name:     "internal",
+			registry: "artifactory.example.com",
+			repo:     "service",
+			want:     "artifactory.example.com/service",
+		},
+		{
+			name:     "backward_compatibility",
+			registry: "artifactory.example.com",
+			repo:     "artifactory.example.com/service",
+			want:     "artifactory.example.com/service",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := buildRepo(tt.registry, tt.repo); got != tt.want {
+				t.Errorf("buildRepo(%q, %q) = %v, want %v", tt.registry, tt.repo, got, tt.want)
+			}
+		})
+	}
+}

cmd/kaniko-ecr/main.go

@@ -14,7 +14,7 @@ import (
 	"github.com/aws/aws-sdk-go-v2/service/ecrpublic"
 	"github.com/aws/smithy-go"
 	kaniko "github.com/drone/drone-kaniko"
-	"github.com/drone/drone-kaniko/cmd/artifact"
+	"github.com/drone/drone-kaniko/pkg/artifact"
 	"github.com/drone/drone-kaniko/pkg/docker"
 	"github.com/joho/godotenv"
 	"github.com/pkg/errors"
@@ -71,6 +71,16 @@ func main() {
 			Value:  ".",
 			EnvVar: "PLUGIN_CONTEXT",
 		},
+		cli.StringFlag{
+			Name:   "drone-commit-ref",
+			Usage:  "git commit ref passed by Drone",
+			EnvVar: "DRONE_COMMIT_REF",
+		},
+		cli.StringFlag{
+			Name:   "drone-repo-branch",
+			Usage:  "git repository default branch passed by Drone",
+			EnvVar: "DRONE_REPO_BRANCH",
+		},
 		cli.StringSliceFlag{
 			Name:     "tags",
 			Usage:    "build tags",
@@ -78,6 +88,21 @@ func main() {
 			EnvVar:   "PLUGIN_TAGS",
 			FilePath: ".tags",
 		},
+		cli.BoolFlag{
+			Name:   "expand-tag",
+			Usage:  "enable for semver tagging",
+			EnvVar: "PLUGIN_EXPAND_TAG",
+		},
+		cli.BoolFlag{
+			Name:   "auto-tag",
+			Usage:  "enable auto generation of build tags",
+			EnvVar: "PLUGIN_AUTO_TAG",
+		},
+		cli.StringFlag{
+			Name:   "auto-tag-suffix",
+			Usage:  "the suffix of auto build tags",
+			EnvVar: "PLUGIN_AUTO_TAG_SUFFIX",
+		},
 		cli.StringSliceFlag{
 			Name:   "args",
 			Usage:  "build args",
@@ -114,6 +139,11 @@ func main() {
 			Usage:  "ECR registry",
 			EnvVar: "PLUGIN_REGISTRY",
 		},
+		cli.StringSliceFlag{
+			Name:   "registry-mirrors",
+			Usage:  "docker registry mirrors",
+			EnvVar: "PLUGIN_REGISTRY_MIRRORS",
+		},
 		cli.StringFlag{
 			Name:   "access-key",
 			Usage:  "ECR access key",
@@ -169,6 +199,11 @@ func main() {
 			Usage:  "Set this flag with value as oneof <panic|fatal|error|warn|info|debug|trace> to set the logging level for kaniko. Defaults to info.",
 			EnvVar: "PLUGIN_VERBOSITY",
 		},
+		cli.StringFlag{
+			Name:   "platform",
+			Usage:  "Allows to build with another default platform than the host, similarly to docker build --platform",
+			EnvVar: "PLUGIN_PLATFORM",
+		},
 	}
 
 	if err := app.Run(os.Args); err != nil {
@@ -232,20 +267,27 @@ func run(c *cli.Context) error {
 
 	plugin := kaniko.Plugin{
 		Build: kaniko.Build{
-			Dockerfile:   c.String("dockerfile"),
-			Context:      c.String("context"),
-			Tags:         c.StringSlice("tags"),
-			Args:         c.StringSlice("args"),
-			Target:       c.String("target"),
-			Repo:         fmt.Sprintf("%s/%s", c.String("registry"), c.String("repo")),
-			Labels:       c.StringSlice("custom-labels"),
-			SnapshotMode: c.String("snapshot-mode"),
-			EnableCache:  c.Bool("enable-cache"),
-			CacheRepo:    fmt.Sprintf("%s/%s", c.String("registry"), c.String("cache-repo")),
-			CacheTTL:     c.Int("cache-ttl"),
-			DigestFile:   defaultDigestFile,
-			NoPush:       noPush,
-			Verbosity:    c.String("verbosity"),
+			DroneCommitRef:  c.String("drone-commit-ref"),
+			DroneRepoBranch: c.String("drone-repo-branch"),
+			Dockerfile:      c.String("dockerfile"),
+			Context:         c.String("context"),
+			Tags:            c.StringSlice("tags"),
+			AutoTag:         c.Bool("auto-tag"),
+			AutoTagSuffix:   c.String("auto-tag-suffix"),
+			ExpandTag:       c.Bool("expand-tag"),
+			Args:            c.StringSlice("args"),
+			Target:          c.String("target"),
+			Repo:            fmt.Sprintf("%s/%s", c.String("registry"), c.String("repo")),
+			Mirrors:         c.StringSlice("registry-mirrors"),
+			Labels:          c.StringSlice("custom-labels"),
+			SnapshotMode:    c.String("snapshot-mode"),
+			EnableCache:     c.Bool("enable-cache"),
+			CacheRepo:       fmt.Sprintf("%s/%s", c.String("registry"), c.String("cache-repo")),
+			CacheTTL:        c.Int("cache-ttl"),
+			DigestFile:      defaultDigestFile,
+			NoPush:          noPush,
+			Verbosity:       c.String("verbosity"),
+			Platform:        c.String("platform"),
 		},
 		Artifact: kaniko.Artifact{
 			Tags:         c.StringSlice("tags"),

cmd/kaniko-gcr/main.go

@@ -11,7 +11,7 @@ import (
 	"github.com/urfave/cli"
 
 	kaniko "github.com/drone/drone-kaniko"
-	"github.com/drone/drone-kaniko/cmd/artifact"
+	"github.com/drone/drone-kaniko/pkg/artifact"
 )
 
 const (
@@ -52,6 +52,16 @@ func main() {
 			Value:  ".",
 			EnvVar: "PLUGIN_CONTEXT",
 		},
+		cli.StringFlag{
+			Name:   "drone-commit-ref",
+			Usage:  "git commit ref passed by Drone",
+			EnvVar: "DRONE_COMMIT_REF",
+		},
+		cli.StringFlag{
+			Name:   "drone-repo-branch",
+			Usage:  "git repository default branch passed by Drone",
+			EnvVar: "DRONE_REPO_BRANCH",
+		},
 		cli.StringSliceFlag{
 			Name:     "tags",
 			Usage:    "build tags",
@@ -59,6 +69,21 @@ func main() {
 			EnvVar:   "PLUGIN_TAGS",
 			FilePath: ".tags",
 		},
+		cli.BoolFlag{
+			Name:   "expand-tag",
+			Usage:  "enable for semver tagging",
+			EnvVar: "PLUGIN_EXPAND_TAG",
+		},
+		cli.BoolFlag{
+			Name:   "auto-tag",
+			Usage:  "enable auto generation of build tags",
+			EnvVar: "PLUGIN_AUTO_TAG",
+		},
+		cli.StringFlag{
+			Name:   "auto-tag-suffix",
+			Usage:  "the suffix of auto build tags",
+			EnvVar: "PLUGIN_AUTO_TAG_SUFFIX",
+		},
 		cli.StringSliceFlag{
 			Name:   "args",
 			Usage:  "build args",
@@ -85,6 +110,11 @@ func main() {
 			Value:  "gcr.io",
 			EnvVar: "PLUGIN_REGISTRY",
 		},
+		cli.StringSliceFlag{
+			Name:   "registry-mirrors",
+			Usage:  "docker registry mirrors",
+			EnvVar: "PLUGIN_REGISTRY_MIRRORS",
+		},
 		cli.StringFlag{
 			Name:   "json-key",
 			Usage:  "docker username",
@@ -125,6 +155,11 @@ func main() {
 			Usage:  "Set this flag as --verbosity=<panic|fatal|error|warn|info|debug|trace> to set the logging level for kaniko. Defaults to info.",
 			EnvVar: "PLUGIN_VERBOSITY",
 		},
+		cli.StringFlag{
+			Name:   "platform",
+			Usage:  "Allows to build with another default platform than the host, similarly to docker build --platform",
+			EnvVar: "PLUGIN_PLATFORM",
+		},
 	}
 
 	if err := app.Run(os.Args); err != nil {
@@ -136,8 +171,10 @@ func run(c *cli.Context) error {
 	noPush := c.Bool("no-push")
 	jsonKey := c.String("json-key")
 
-	// only setup auth when pushing or credentials are defined
-	if !noPush || jsonKey != "" {
+	// JSON key may not be set in the following cases:
+	// 1. Image does not need to be pushed to GCR.
+	// 2. Workload identity is set on GKE in which pod will inherit the credentials via service account.
+	if jsonKey != "" {
 		if err := setupGCRAuth(jsonKey); err != nil {
 			return err
 		}
@@ -145,20 +182,27 @@ func run(c *cli.Context) error {
 
 	plugin := kaniko.Plugin{
 		Build: kaniko.Build{
-			Dockerfile:   c.String("dockerfile"),
-			Context:      c.String("context"),
-			Tags:         c.StringSlice("tags"),
-			Args:         c.StringSlice("args"),
-			Target:       c.String("target"),
-			Repo:         fmt.Sprintf("%s/%s", c.String("registry"), c.String("repo")),
-			Labels:       c.StringSlice("custom-labels"),
-			SnapshotMode: c.String("snapshot-mode"),
-			EnableCache:  c.Bool("enable-cache"),
-			CacheRepo:    fmt.Sprintf("%s/%s", c.String("registry"), c.String("cache-repo")),
-			CacheTTL:     c.Int("cache-ttl"),
-			DigestFile:   defaultDigestFile,
-			NoPush:       noPush,
-			Verbosity:    c.String("verbosity"),
+			DroneCommitRef:  c.String("drone-commit-ref"),
+			DroneRepoBranch: c.String("drone-repo-branch"),
+			Dockerfile:      c.String("dockerfile"),
+			Context:         c.String("context"),
+			Tags:            c.StringSlice("tags"),
+			AutoTag:         c.Bool("auto-tag"),
+			AutoTagSuffix:   c.String("auto-tag-suffix"),
+			ExpandTag:       c.Bool("expand-tag"),
+			Args:            c.StringSlice("args"),
+			Target:          c.String("target"),
+			Repo:            fmt.Sprintf("%s/%s", c.String("registry"), c.String("repo")),
+			Mirrors:         c.StringSlice("registry-mirrors"),
+			Labels:          c.StringSlice("custom-labels"),
+			SnapshotMode:    c.String("snapshot-mode"),
+			EnableCache:     c.Bool("enable-cache"),
+			CacheRepo:       fmt.Sprintf("%s/%s", c.String("registry"), c.String("cache-repo")),
+			CacheTTL:        c.Int("cache-ttl"),
+			DigestFile:      defaultDigestFile,
+			NoPush:          noPush,
+			Verbosity:       c.String("verbosity"),
+			Platform:        c.String("platform"),
 		},
 		Artifact: kaniko.Artifact{
 			Tags:         c.StringSlice("tags"),
@@ -172,10 +216,6 @@ func run(c *cli.Context) error {
 }
 
 func setupGCRAuth(jsonKey string) error {
-	if jsonKey == "" {
-		return fmt.Errorf("GCR JSON key must be specified")
-	}
-
 	err := ioutil.WriteFile(gcrKeyPath, []byte(jsonKey), 0644)
 	if err != nil {
 		return errors.Wrap(err, "failed to write GCR JSON key")

docker/docker/Dockerfile.linux.amd64

@@ -1,4 +1,4 @@
-FROM gcr.io/kaniko-project/executor:v1.5.2
+FROM gcr.io/kaniko-project/executor:v1.6.0
 
 ADD release/linux/amd64/kaniko-docker /kaniko/
 ENTRYPOINT ["/kaniko/kaniko-docker"]

docker/docker/Dockerfile.linux.amd64.kaniko1.8.0

@@ -0,0 +1,4 @@
+FROM gcr.io/kaniko-project/executor:v1.8.0
+
+ADD release/linux/amd64/kaniko-docker /kaniko/
+ENTRYPOINT ["/kaniko/kaniko-docker"]

docker/docker/Dockerfile.linux.arm64

@@ -1,4 +1,4 @@
-FROM gcr.io/kaniko-project/executor:arm64-v1.5.2
+FROM gcr.io/kaniko-project/executor:arm64-v1.6.0
 
 ENV HOME /root
 ENV USER root

docker/docker/manifest-kaniko1.8.0.tmpl

@@ -0,0 +1,13 @@
+image: plugins/kaniko:{{#if build.tag}}{{trimPrefix "v" build.tag}}-kaniko1.8.0{{else}}latest-kaniko1.8.0{{/if}}
+{{#if build.tags}}
+tags:
+{{#each build.tags}}
+  - {{this}}
+{{/each}}
+{{/if}}
+manifests:
+  -
+    image: plugins/kaniko:{{#if build.tag}}{{trimPrefix "v" build.tag}}-{{/if}}linux-amd64-kaniko1.8.0
+    platform:
+      architecture: amd64
+      os: linux

docker/ecr/Dockerfile.linux.amd64

@@ -1,4 +1,4 @@
-FROM gcr.io/kaniko-project/executor:v1.5.2
+FROM gcr.io/kaniko-project/executor:v1.6.0
 
 ADD release/linux/amd64/kaniko-ecr /kaniko/
 ENTRYPOINT ["/kaniko/kaniko-ecr"]

docker/ecr/Dockerfile.linux.amd64.kaniko1.8.0

@@ -0,0 +1,4 @@
+FROM gcr.io/kaniko-project/executor:v1.8.0
+
+ADD release/linux/amd64/kaniko-ecr /kaniko/
+ENTRYPOINT ["/kaniko/kaniko-ecr"]

docker/ecr/Dockerfile.linux.arm64

@@ -1,4 +1,4 @@
-FROM gcr.io/kaniko-project/executor:arm64-v1.5.2
+FROM gcr.io/kaniko-project/executor:arm64-v1.6.0
 
 ENV HOME /root
 ENV USER root

docker/ecr/manifest-kaniko1.8.0.tmpl

@@ -0,0 +1,13 @@
+image: plugins/kaniko-ecr:{{#if build.tag}}{{trimPrefix "v" build.tag}}-kaniko1.8.0{{else}}latest-kaniko1.8.0{{/if}}
+{{#if build.tags}}
+tags:
+{{#each build.tags}}
+  - {{this}}
+{{/each}}
+{{/if}}
+manifests:
+  -
+    image: plugins/kaniko-ecr:{{#if build.tag}}{{trimPrefix "v" build.tag}}-{{/if}}linux-amd64-kaniko1.8.0
+    platform:
+      architecture: amd64
+      os: linux

docker/gcr/Dockerfile.linux.amd64

@@ -1,4 +1,4 @@
-FROM gcr.io/kaniko-project/executor:v1.5.2
+FROM gcr.io/kaniko-project/executor:v1.6.0
 
 ADD release/linux/amd64/kaniko-gcr /kaniko/
 ENTRYPOINT ["/kaniko/kaniko-gcr"]

docker/gcr/Dockerfile.linux.amd64.kaniko1.8.0

@@ -0,0 +1,4 @@
+FROM gcr.io/kaniko-project/executor:v1.8.0
+
+ADD release/linux/amd64/kaniko-gcr /kaniko/
+ENTRYPOINT ["/kaniko/kaniko-gcr"]

docker/gcr/Dockerfile.linux.arm64

@@ -1,4 +1,4 @@
-FROM gcr.io/kaniko-project/executor:arm64-v1.5.2
+FROM gcr.io/kaniko-project/executor:arm64-v1.6.0
 
 ENV HOME /root
 ENV USER root

docker/gcr/manifest-kaniko1.8.0.tmpl

@@ -0,0 +1,13 @@
+image: plugins/kaniko-gcr:{{#if build.tag}}{{trimPrefix "v" build.tag}}-kaniko1.8.0{{else}}latest-kaniko1.8.0{{/if}}
+{{#if build.tags}}
+tags:
+{{#each build.tags}}
+  - {{this}}
+{{/each}}
+{{/if}}
+manifests:
+  -
+    image: plugins/kaniko-gcr:{{#if build.tag}}{{trimPrefix "v" build.tag}}-{{/if}}linux-amd64-kaniko1.8.0
+    platform:
+      architecture: amd64
+      os: linux

go.mod

@@ -6,10 +6,29 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/ecr v1.4.3
 	github.com/aws/aws-sdk-go-v2/service/ecrpublic v1.4.3
 	github.com/aws/smithy-go v1.7.0
+	github.com/coreos/go-semver v0.3.0
+	github.com/google/go-cmp v0.5.6
 	github.com/joho/godotenv v1.3.0
 	github.com/pkg/errors v0.9.1
 	github.com/sirupsen/logrus v1.3.0
 	github.com/urfave/cli v1.22.2
+	golang.org/x/mod v0.4.2
 )
 
-go 1.13
+require (
+	github.com/aws/aws-sdk-go-v2/credentials v1.3.3 // indirect
+	github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.4.1 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/ini v1.2.1 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.2.3 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sso v1.3.3 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sts v1.6.2 // indirect
+	github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d // indirect
+	github.com/jmespath/go-jmespath v0.4.0 // indirect
+	github.com/konsorten/go-windows-terminal-sequences v1.0.1 // indirect
+	github.com/russross/blackfriday/v2 v2.0.1 // indirect
+	github.com/shurcooL/sanitized_anchor_name v1.0.0 // indirect
+	golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550 // indirect
+	golang.org/x/sys v0.0.0-20190412213103-97732733099d // indirect
+)
+
+go 1.17

go.sum

@@ -21,6 +21,8 @@ github.com/aws/aws-sdk-go-v2/service/sts v1.6.2 h1:l504GWCoQi1Pk68vSUFGLmDIEMzRf
 github.com/aws/aws-sdk-go-v2/service/sts v1.6.2/go.mod h1:RBhoMJB8yFToaCnbe0jNq5Dcdy0jp6LhHqg55rjClkM=
 github.com/aws/smithy-go v1.7.0 h1:+cLHMRrDZvQ4wk+KuQ9yH6eEg6KZEJ9RI2IkDqnygCg=
 github.com/aws/smithy-go v1.7.0/go.mod h1:SObp3lf9smib00L/v3U2eAKG8FyQ7iLrJnQiAmR5n+E=
+github.com/coreos/go-semver v0.3.0 h1:wkHLiw0WNATZnSG7epLsujiMCgPAc9xhjJ4tgnAxmfM=
+github.com/coreos/go-semver v0.3.0/go.mod h1:nnelYz7RCh+5ahJtPPxZlU+153eP4D4r3EedlOD2RNk=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d h1:U+s90UTSYgptZMwQh2aRr3LuazLJIa+Pg3Kc1ylSYVY=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
@@ -53,13 +55,25 @@ github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/urfave/cli v1.22.2 h1:gsqYFH8bb9ekPA12kRo0hfjngWQjkJPlN9R0N78BoUo=
 github.com/urfave/cli v1.22.2/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
-golang.org/x/crypto v0.0.0-20180904163835-0709b304e793 h1:u+LnwYTOOW7Ukr/fppxEb1Nwz0AtPflrblfvUudpo+I=
 golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
-golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33 h1:I6FyU15t786LL7oL/hn43zqTuEGr4PN7F4XJ1p4E3Y8=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550 h1:ObdrDkeb4kJdCP557AjRjq69pTHfNouLtWZG7j9rPN8=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/mod v0.4.2 h1:Gz96sIWK3OalVv/I/qNygP42zyoKp3xptRVCWRFEBvo=
+golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d h1:+R4KGOnez64A81RvjARKc4UT5/tI9ujCIVX+P5KiHuI=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.8 h1:obN1ZagJSUGI0Ek/LBmuj4SNLPfIny3KsKFopxRdj10=

kaniko.go

@@ -7,28 +7,38 @@ import (
 	"os/exec"
 	"strings"
 
-	"github.com/drone/drone-kaniko/cmd/artifact"
+	"github.com/drone/drone-kaniko/pkg/artifact"
+	"github.com/drone/drone-kaniko/pkg/tagger"
+	"golang.org/x/mod/semver"
 )
 
 type (
 	// Build defines Docker build parameters.
 	Build struct {
-		Dockerfile    string   // Docker build Dockerfile
-		Context       string   // Docker build context
-		Tags          []string // Docker build tags
-		Args          []string // Docker build args
-		Target        string   // Docker build target
-		Repo          string   // Docker build repository
-		Labels        []string // Label map
-		SkipTlsVerify bool     // Docker skip tls certificate verify for registry
-		SnapshotMode  string   // Kaniko snapshot mode
-		EnableCache   bool     // Whether to enable kaniko cache
-		CacheRepo     string   // Remote repository that will be used to store cached layers
-		CacheTTL      int      // Cache timeout in hours
-		DigestFile    string   // Digest file location
-		NoPush        bool     // Set this flag if you only want to build the image, without pushing to a registry
-		Verbosity     string   // Log level
+		DroneCommitRef  string   // Drone git commit reference
+		DroneRepoBranch string   // Drone repo branch
+		Dockerfile      string   // Docker build Dockerfile
+		Context         string   // Docker build context
+		Tags            []string // Docker build tags
+		AutoTag         bool     // Set this to auto detect tags from git commits and semver-tagged labels
+		AutoTagSuffix   string   // Suffix to append to the auto detect tags
+		ExpandTag       bool     // Set this to expand the `Tags` into semver-tagged labels
+		Args            []string // Docker build args
+		Target          string   // Docker build target
+		Repo            string   // Docker build repository
+		Mirrors         []string // Docker repository mirrors
+		Labels          []string // Label map
+		SkipTlsVerify   bool     // Docker skip tls certificate verify for registry
+		SnapshotMode    string   // Kaniko snapshot mode
+		EnableCache     bool     // Whether to enable kaniko cache
+		CacheRepo       string   // Remote repository that will be used to store cached layers
+		CacheTTL        int      // Cache timeout in hours
+		DigestFile      string   // Digest file location
+		NoPush          bool     // Set this flag if you only want to build the image, without pushing to a registry
+		Verbosity       string   // Log level
+		Platform        string   // Allows to build with another default platform than the host, similarly to docker build --platform
 	}
+
 	// Artifact defines content of artifact file
 	Artifact struct {
 		Tags         []string                  // Docker artifact tags
@@ -45,6 +55,71 @@ type (
 	}
 )
 
+// labelsForTag returns the labels to use for the given tag, subject to the value of ExpandTag.
+//
+// Build information (e.g. +linux_amd64) is carried through to all labels.
+// Pre-release information (e.g. -rc1) suppresses major and major+minor auto-labels.
+func (b Build) labelsForTag(tag string) (labels []string) {
+	// We strip "v" off of the beginning of semantic versions, as they are not used in docker tags
+	const VersionPrefix = "v"
+
+	// Semantic Versions don't allow underscores, so replace them with dashes.
+	//   https://semver.org/
+	semverTag := strings.ReplaceAll(tag, "_", "-")
+
+	// Allow tags of the form "1.2.3" as well as "v1.2.3" to avoid confusion.
+	if withV := VersionPrefix + semverTag; !semver.IsValid(semverTag) && semver.IsValid(withV) {
+		semverTag = withV
+	}
+
+	// Pass through tags if expand-tag is not set, or if the tag is not a semantic version
+	if !b.ExpandTag || !semver.IsValid(semverTag) {
+		return []string{tag}
+	}
+	tag = semverTag
+
+	// If the version is pre-release, only the full release should be tagged, not the major/minor versions.
+	if semver.Prerelease(tag) != "" {
+		return []string{
+			strings.TrimPrefix(tag, VersionPrefix),
+		}
+	}
+
+	// tagFor carries any build information from the semantic version through to major and minor tags.
+	labelFor := func(base string) string {
+		return strings.TrimPrefix(base, VersionPrefix) + semver.Build(tag)
+	}
+	return []string{
+		labelFor(semver.Major(tag)),
+		labelFor(semver.MajorMinor(tag)),
+		labelFor(semver.Canonical(tag)),
+	}
+}
+
+// Returns the auto detected tags. See the AutoTag section of
+// https://plugins.drone.io/drone-plugins/drone-docker/ for more info.
+func (b Build) AutoTags() (tags []string, err error) {
+	if len(b.Tags) > 1 || len(b.Tags) == 1 && b.Tags[0] != "latest" {
+		err = fmt.Errorf("The auto-tag flag does not work with user provided tags %s", b.Tags)
+		return
+	}
+	// We have tried the best to prevent enabling auto-tag and passing in
+	// user specified at the same time. Starts to auto detect tags.
+	// Note: passing in a "latest" tag with auto-tag enabled won't trigger the
+	// early returns above, because we cannot tell if the tag is provided by
+	// the default value or by the users.
+	commitRef := b.DroneCommitRef
+	if !tagger.UseAutoTag(commitRef, b.DroneRepoBranch) {
+		err = fmt.Errorf("Could not auto detect the tag. Skipping automated docker build for commit %s", commitRef)
+		return
+	}
+	tags, err = tagger.AutoTagsSuffix(commitRef, b.AutoTagSuffix)
+	if err != nil {
+		err = fmt.Errorf("Invalid semantic version when auto detecting the tag. Skipping automated docker build for %s.", commitRef)
+	}
+	return
+}
+
 // Exec executes the plugin step
 func (p Plugin) Exec() error {
 	if !p.Build.NoPush && p.Build.Repo == "" {
@@ -55,6 +130,18 @@ func (p Plugin) Exec() error {
 		return fmt.Errorf("dockerfile does not exist at path: %s", p.Build.Dockerfile)
 	}
 
+	var tags = p.Build.Tags
+	if p.Build.AutoTag && p.Build.ExpandTag {
+		return fmt.Errorf("The auto-tag flag conflicts with the expand-tag flag")
+	}
+	if p.Build.AutoTag {
+		var err error
+		tags, err = p.Build.AutoTags()
+		if err != nil {
+			return err
+		}
+	}
+
 	cmdArgs := []string{
 		fmt.Sprintf("--dockerfile=%s", p.Build.Dockerfile),
 		fmt.Sprintf("--context=dir://%s", p.Build.Context),
@@ -62,8 +149,10 @@ func (p Plugin) Exec() error {
 
 	// Set the destination repository
 	if !p.Build.NoPush {
-		for _, tag := range p.Build.Tags {
-			cmdArgs = append(cmdArgs, fmt.Sprintf("--destination=%s:%s", p.Build.Repo, tag))
+		for _, tag := range tags {
+			for _, label := range p.Build.labelsForTag(tag) {
+				cmdArgs = append(cmdArgs, fmt.Sprintf("--destination=%s:%s", p.Build.Repo, label))
+			}
 		}
 	}
 	// Set the build arguments
@@ -74,7 +163,10 @@ func (p Plugin) Exec() error {
 	for _, label := range p.Build.Labels {
 		cmdArgs = append(cmdArgs, fmt.Sprintf("--label=%s", label))
 	}
-
+	// Set repository mirrors
+	for _, mirror := range p.Build.Mirrors {
+		cmdArgs = append(cmdArgs, fmt.Sprintf("--registry-mirror=%s", mirror))
+	}
 	if p.Build.Target != "" {
 		cmdArgs = append(cmdArgs, fmt.Sprintf("--target=%s", p.Build.Target))
 	}
@@ -96,7 +188,7 @@ func (p Plugin) Exec() error {
 	}
 
 	if p.Build.CacheTTL != 0 {
-		cmdArgs = append(cmdArgs, fmt.Sprintf("--cache-ttl=%d", p.Build.CacheTTL))
+		cmdArgs = append(cmdArgs, fmt.Sprintf("--cache-ttl=%dh", p.Build.CacheTTL))
 	}
 
 	if p.Build.DigestFile != "" {
@@ -111,6 +203,10 @@ func (p Plugin) Exec() error {
 		cmdArgs = append(cmdArgs, fmt.Sprintf("--verbosity=%s", p.Build.Verbosity))
 	}
 
+	if p.Build.Platform != "" {
+		cmdArgs = append(cmdArgs, fmt.Sprintf("--customPlatform=%s", p.Build.Platform))
+	}
+
 	cmd := exec.Command("/kaniko/executor", cmdArgs...)
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr

kaniko_test.go

@@ -1 +1,141 @@
 package kaniko
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestBuild_labelsForTag(t *testing.T) {
+	tests := []struct {
+		name       string
+		tag        string
+		expandTags []string
+	}{
+		{
+			name:       "semver",
+			tag:        "v1.2.3",
+			expandTags: []string{"1", "1.2", "1.2.3"},
+		},
+		{
+			name:       "no_patch",
+			tag:        "v1.2",
+			expandTags: []string{"1", "1.2", "1.2.0"},
+		},
+		{
+			name:       "only_major",
+			tag:        "v1",
+			expandTags: []string{"1", "1.0", "1.0.0"},
+		},
+		{
+			name:       "full_with_build",
+			tag:        "v1.2.3+build-info",
+			expandTags: []string{"1+build-info", "1.2+build-info", "1.2.3+build-info"},
+		},
+		{
+			name:       "build_with_underscores",
+			tag:        "v1.2.3+linux_amd64",
+			expandTags: []string{"1+linux-amd64", "1.2+linux-amd64", "1.2.3+linux-amd64"},
+		},
+		{
+			name:       "prerelease",
+			tag:        "v1.2.3-rc1",
+			expandTags: []string{"1.2.3-rc1"},
+		},
+		{
+			name:       "prerelease_with_build",
+			tag:        "v1.2.3-rc1+bld",
+			expandTags: []string{"1.2.3-rc1+bld"},
+		},
+		{
+			name:       "invalid_build",
+			tag:        "v1+bld", // can only include build detail with all three elements
+			expandTags: []string{"v1+bld"},
+		},
+		{
+			name:       "accidental_non_semver",
+			tag:        "1.2.3",
+			expandTags: []string{"1", "1.2", "1.2.3"},
+		},
+		{
+			name:       "non_semver",
+			tag:        "latest",
+			expandTags: []string{"latest"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tags := Build{ExpandTag: true}.labelsForTag(tt.tag)
+			if got, want := tags, tt.expandTags; !cmp.Equal(got, want) {
+				t.Errorf("tagsFor(%q) = %q, want %q", tt.tag, got, want)
+			}
+		})
+	}
+}
+
+func TestBuild_AutoTags(t *testing.T) {
+	tests := []struct {
+		name          string
+		repoBranch    string
+		commitRef     string
+		autoTagSuffix string
+		expectedTags  []string
+	}{
+		{
+			name:          "commit push",
+			repoBranch:    "master",
+			commitRef:     "refs/heads/master",
+			autoTagSuffix: "",
+			expectedTags:  []string{"latest"},
+		},
+		{
+			name:          "tag push",
+			repoBranch:    "master",
+			commitRef:     "refs/tags/v1.0.0",
+			autoTagSuffix: "",
+			expectedTags: []string{
+				"1",
+				"1.0",
+				"1.0.0",
+			},
+		},
+		{
+			name:          "tag push",
+			repoBranch:    "master",
+			commitRef:     "refs/tags/v1.0.0",
+			autoTagSuffix: "linux-amd64",
+			expectedTags: []string{
+				"1-linux-amd64",
+				"1.0-linux-amd64",
+				"1.0.0-linux-amd64",
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			b := Build{DroneCommitRef: tt.commitRef, DroneRepoBranch: tt.repoBranch, AutoTag: true}
+			if tt.autoTagSuffix != "" {
+				b.AutoTagSuffix = tt.autoTagSuffix
+			}
+			tags, err := b.AutoTags()
+			if err != nil {
+				t.Errorf("Unexpected err %q", err)
+			}
+			if got, want := tags, tt.expectedTags; !cmp.Equal(got, want) {
+				t.Errorf("auto detected tags = %q, wanted = %q", got, want)
+			}
+		})
+	}
+	t.Run("auto-tag cannot be enabled with user provided tags", func(t *testing.T) {
+		b := Build{
+			DroneCommitRef:  "refs/tags/v1.0.0",
+			DroneRepoBranch: "master",
+			AutoTag:         true,
+			Tags:            []string{"v1"},
+		}
+		_, err := b.AutoTags()
+		if err == nil {
+			t.Errorf("Expect error for invalid flags")
+		}
+	})
+}

pkg/tagger/tagger.go

@@ -0,0 +1,95 @@
+// A fork of https://github.com/drone-plugins/drone-docker/blob/master/tags.go
+
+package tagger
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/coreos/go-semver/semver"
+)
+
+// AutoTagsSuffix returns a set of default suggested tags
+// based on the commit ref with an attached suffix.
+func AutoTagsSuffix(ref, suffix string) ([]string, error) {
+	tags, err := AutoTags(ref)
+	if err != nil {
+		return nil, err
+	}
+	if len(suffix) == 0 {
+		return tags, nil
+	}
+	for i, tag := range tags {
+		if tag == "latest" {
+			tags[i] = suffix
+		} else {
+			tags[i] = fmt.Sprintf("%s-%s", tag, suffix)
+		}
+	}
+	return tags, nil
+}
+
+func splitOff(input string, delim string) string {
+	parts := strings.SplitN(input, delim, 2)
+
+	if len(parts) == 2 {
+		return parts[0]
+	}
+
+	return input
+}
+
+// AutoTags returns a set of default suggested tags based on
+// the commit ref.
+func AutoTags(ref string) ([]string, error) {
+	if !strings.HasPrefix(ref, "refs/tags/") {
+		return []string{"latest"}, nil
+	}
+	v := stripTagPrefix(ref)
+	version, err := semver.NewVersion(v)
+	if err != nil {
+		return []string{"latest"}, err
+	}
+	if version.PreRelease != "" || version.Metadata != "" {
+		return []string{
+			version.String(),
+		}, nil
+	}
+
+	v = stripTagPrefix(ref)
+	v = splitOff(splitOff(v, "+"), "-")
+	dotParts := strings.SplitN(v, ".", 3)
+
+	if version.Major == 0 {
+		return []string{
+			fmt.Sprintf("%0*d.%0*d", len(dotParts[0]), version.Major, len(dotParts[1]), version.Minor),
+			fmt.Sprintf("%0*d.%0*d.%0*d", len(dotParts[0]), version.Major, len(dotParts[1]), version.Minor, len(dotParts[2]), version.Patch),
+		}, nil
+	}
+	return []string{
+		fmt.Sprintf("%0*d", len(dotParts[0]), version.Major),
+		fmt.Sprintf("%0*d.%0*d", len(dotParts[0]), version.Major, len(dotParts[1]), version.Minor),
+		fmt.Sprintf("%0*d.%0*d.%0*d", len(dotParts[0]), version.Major, len(dotParts[1]), version.Minor, len(dotParts[2]), version.Patch),
+	}, nil
+}
+
+// UseAutoTag for keep only default branch for latest tag.
+func UseAutoTag(ref, defaultBranch string) bool {
+	if strings.HasPrefix(ref, "refs/tags/") {
+		return true
+	}
+	if stripHeadPrefix(ref) == defaultBranch {
+		return true
+	}
+	return false
+}
+
+func stripHeadPrefix(ref string) string {
+	return strings.TrimPrefix(ref, "refs/heads/")
+}
+
+func stripTagPrefix(ref string) string {
+	ref = strings.TrimPrefix(ref, "refs/tags/")
+	ref = strings.TrimPrefix(ref, "v")
+	return ref
+}

pkg/tagger/tagger_test.go

@@ -0,0 +1,199 @@
+// A fork of https://github.com/drone-plugins/drone-docker/blob/master/tags_test.go
+
+package tagger
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_stripTagPrefix(t *testing.T) {
+	var tests = []struct {
+		Before string
+		After  string
+	}{
+		{"refs/tags/1.0.0", "1.0.0"},
+		{"refs/tags/v1.0.0", "1.0.0"},
+		{"v1.0.0", "1.0.0"},
+	}
+
+	for _, test := range tests {
+		got, want := stripTagPrefix(test.Before), test.After
+		if got != want {
+			t.Errorf("Got tag %s, want %s", got, want)
+		}
+	}
+}
+
+func TestAutoTags(t *testing.T) {
+	var tests = []struct {
+		Before string
+		After  []string
+	}{
+		{"", []string{"latest"}},
+		{"refs/heads/master", []string{"latest"}},
+		{"refs/tags/0.9.0", []string{"0.9", "0.9.0"}},
+		{"refs/tags/1.0.0", []string{"1", "1.0", "1.0.0"}},
+		{"refs/tags/v1.0.0", []string{"1", "1.0", "1.0.0"}},
+		{"refs/tags/v1.0.0-alpha.1", []string{"1.0.0-alpha.1"}},
+	}
+
+	for _, test := range tests {
+		tags, err := AutoTags(test.Before)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+		got, want := tags, test.After
+		if !reflect.DeepEqual(got, want) {
+			t.Errorf("Got tag %v, want %v", got, want)
+		}
+	}
+}
+
+func TestAutoTagsError(t *testing.T) {
+	var tests = []string{
+		"refs/tags/x1.0.0",
+		"refs/tags/20190203",
+	}
+
+	for _, test := range tests {
+		_, err := AutoTags(test)
+		if err == nil {
+			t.Errorf("Expect tag error for %s", test)
+		}
+	}
+}
+
+func TestAutoTagsSuffix(t *testing.T) {
+	var tests = []struct {
+		Before string
+		Suffix string
+		After  []string
+	}{
+		// without suffix
+		{
+			After: []string{"latest"},
+		},
+		{
+			Before: "refs/tags/v1.0.0",
+			After: []string{
+				"1",
+				"1.0",
+				"1.0.0",
+			},
+		},
+		// with suffix
+		{
+			Suffix: "linux-amd64",
+			After:  []string{"linux-amd64"},
+		},
+		{
+			Before: "refs/tags/v1.0.0",
+			Suffix: "linux-amd64",
+			After: []string{
+				"1-linux-amd64",
+				"1.0-linux-amd64",
+				"1.0.0-linux-amd64",
+			},
+		},
+		{
+			Suffix: "nanoserver",
+			After:  []string{"nanoserver"},
+		},
+		{
+			Before: "refs/tags/v1.9.2",
+			Suffix: "nanoserver",
+			After: []string{
+				"1-nanoserver",
+				"1.9-nanoserver",
+				"1.9.2-nanoserver",
+			},
+		},
+		{
+			Before: "refs/tags/v18.06.0",
+			Suffix: "nanoserver",
+			After: []string{
+				"18-nanoserver",
+				"18.06-nanoserver",
+				"18.06.0-nanoserver",
+			},
+		},
+	}
+
+	for _, test := range tests {
+		tag, err := AutoTagsSuffix(test.Before, test.Suffix)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+		got, want := tag, test.After
+		if !reflect.DeepEqual(got, want) {
+			t.Errorf("Got tag %v, want %v", got, want)
+		}
+	}
+}
+
+func Test_stripHeadPrefix(t *testing.T) {
+	type args struct {
+		ref string
+	}
+	tests := []struct {
+		args args
+		want string
+	}{
+		{
+			args: args{
+				ref: "refs/heads/master",
+			},
+			want: "master",
+		},
+	}
+	for _, tt := range tests {
+		if got := stripHeadPrefix(tt.args.ref); got != tt.want {
+			t.Errorf("stripHeadPrefix() = %v, want %v", got, tt.want)
+		}
+	}
+}
+
+func TestUseAutoTag(t *testing.T) {
+	type args struct {
+		ref           string
+		defaultBranch string
+	}
+	tests := []struct {
+		name string
+		args args
+		want bool
+	}{
+		{
+			name: "latest tag for default branch",
+			args: args{
+				ref:           "refs/heads/master",
+				defaultBranch: "master",
+			},
+			want: true,
+		},
+		{
+			name: "build from tags",
+			args: args{
+				ref:           "refs/tags/v1.0.0",
+				defaultBranch: "master",
+			},
+			want: true,
+		},
+		{
+			name: "skip build for not default branch",
+			args: args{
+				ref:           "refs/heads/develop",
+				defaultBranch: "master",
+			},
+			want: false,
+		},
+	}
+	for _, tt := range tests {
+		if got := UseAutoTag(tt.args.ref, tt.args.defaultBranch); got != tt.want {
+			t.Errorf("%q. UseAutoTag() = %v, want %v", tt.name, got, tt.want)
+		}
+	}
+}