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[](https://github.com/docker/metadata-action/releases/latest)
[](https://github.com/marketplace/actions/docker-metadata-action)
[](https://github.com/docker/metadata-action/actions?workflow=test)
[](https://codecov.io/gh/docker/metadata-action)
## About
GitHub Action to extract metadata from Git reference and GitHub events.
This action is particularly useful if used with [Docker Build Push](https://github.com/docker/build-push-action) action to tag and label Docker images.
___
* [Usage](#usage)
* [Basic](#basic)
* [Semver](#semver)
* [Bake definition](#bake-definition)
* [Customizing](#customizing)
* [inputs](#inputs)
* [outputs](#outputs)
* [`images` input](#images-input)
* [`flavor` input](#flavor-input)
* [`tags` input](#tags-input)
* [`type=schedule`](#typeschedule)
* [`type=semver`](#typesemver)
* [`type=pep440`](#typepep440)
* [`type=match`](#typematch)
* [`type=edge`](#typeedge)
* [`type=ref`](#typeref)
* [`type=raw`](#typeraw)
* [`type=sha`](#typesha)
* [Notes](#notes)
* [Latest tag](#latest-tag)
* [Global expressions](#global-expressions)
* [`{{branch}}`](#branch)
* [`{{tag}}`](#tag)
* [`{{sha}}`](#sha)
* [`{{base_ref}}`](#base_ref)
* [`{{is_default_branch}}`](#is_default_branch)
* [`{{date '<format>'}}`](#date-format)
* [Major version zero](#major-version-zero)
* [JSON output object](#json-output-object)
* [Overwrite labels](#overwrite-labels)
* [Keep up-to-date with GitHub Dependabot](#keep-up-to-date-with-github-dependabot)
## Usage
### Basic
```yaml
name: ci
on:
push:
branches:
- 'master'
tags:
- 'v*'
pull_request:
branches:
- 'master'
jobs:
docker:
runs-on: ubuntu-latest
steps:
-
name: Checkout
uses: actions/checkout@v2
-
name: Docker meta
id: meta
uses: docker/metadata-action@v3
with:
images: name/app
-
name: Login to DockerHub
if: github.event_name != 'pull_request'
uses: docker/login-action@v1
with:
username: ${{ secrets.DOCKERHUB_USERNAME }}
password: ${{ secrets.DOCKERHUB_TOKEN }}
-
name: Build and push
uses: docker/build-push-action@v2
with:
context: .
push: ${{ github.event_name != 'pull_request' }}
tags: ${{ steps.meta.outputs.tags }}
labels: ${{ steps.meta.outputs.labels }}
```
| Event | Ref | Docker Tags |
|-----------------|-------------------------------|-------------------------------------|
| `pull_request` | `refs/pull/2/merge` | `pr-2` |
| `push` | `refs/heads/master` | `master` |
| `push` | `refs/heads/releases/v1` | `releases-v1` |
| `push tag` | `refs/tags/v1.2.3` | `v1.2.3`, `latest` |
| `push tag` | `refs/tags/v2.0.8-beta.67` | `v2.0.8-beta.67`, `latest` |
### Semver
```yaml
name: ci
on:
push:
branches:
- 'master'
tags:
- 'v*'
pull_request:
branches:
- 'master'
jobs:
docker:
runs-on: ubuntu-latest
steps:
-
name: Checkout
uses: actions/checkout@v2
-
name: Docker meta
id: meta
uses: docker/metadata-action@v3
with:
images: |
name/app
tags: |
type=ref,event=branch
type=ref,event=pr
type=semver,pattern={{version}}
type=semver,pattern={{major}}.{{minor}}
-
name: Login to DockerHub
if: github.event_name != 'pull_request'
uses: docker/login-action@v1
with:
username: ${{ secrets.DOCKERHUB_USERNAME }}
password: ${{ secrets.DOCKERHUB_TOKEN }}
-
name: Build and push
uses: docker/build-push-action@v2
with:
context: .
push: ${{ github.event_name != 'pull_request' }}
tags: ${{ steps.meta.outputs.tags }}
labels: ${{ steps.meta.outputs.labels }}
```
| Event | Ref | Docker Tags |
|-----------------|-------------------------------|-------------------------------------|
| `pull_request` | `refs/pull/2/merge` | `pr-2` |
| `push` | `refs/heads/master` | `master` |
| `push` | `refs/heads/releases/v1` | `releases-v1` |
| `push tag` | `refs/tags/v1.2.3` | `1.2.3`, `1.2`, `latest` |
| `push tag` | `refs/tags/v2.0.8-beta.67` | `2.0.8-beta.67` |
### Bake definition
This action also handles a bake definition file that can be used with the
[Docker Bake action](https://github.com/docker/bake-action). You just have to declare an empty target named
`docker-metadata-action` and inherit from it.
```hcl
// docker-bake.hcl
target "docker-metadata-action" {}
target "build" {
inherits = ["docker-metadata-action"]
context = "./"
dockerfile = "Dockerfile"
platforms = [
"linux/amd64",
"linux/arm/v6",
"linux/arm/v7",
"linux/arm64",
"linux/386"
]
}
```
```yaml
name: ci
on:
push:
branches:
- 'master'
tags:
- 'v*'
jobs:
docker:
runs-on: ubuntu-latest
steps:
-
name: Checkout
uses: actions/checkout@v2
-
name: Docker meta
id: meta
uses: docker/metadata-action@v3
with:
images: |
name/app
tags: |
type=ref,event=branch
type=ref,event=pr
type=semver,pattern={{version}}
type=semver,pattern={{major}}.{{minor}}
type=sha
-
name: Build
uses: docker/bake-action@v1
with:
files: |
./docker-bake.hcl
${{ steps.meta.outputs.bake-file }}
targets: build
```
Content of `${{ steps.meta.outputs.bake-file }}` file will look like this with `refs/tags/v1.2.3` ref:
```json
{
"target": {
"docker-metadata-action": {
"tags": [
"name/app:1.2.3",
"name/app:1.2",
"name/app:sha-90dd603",
"name/app:latest"
],
"labels": {
"org.opencontainers.image.title": "Hello-World",
"org.opencontainers.image.description": "This your first repo!",
"org.opencontainers.image.url": "https://github.com/octocat/Hello-World",
"org.opencontainers.image.source": "https://github.com/octocat/Hello-World",
"org.opencontainers.image.version": "1.2.3",
"org.opencontainers.image.created": "2020-01-10T00:30:00.000Z",
"org.opencontainers.image.revision": "860c1904a1ce19322e91ac35af1ab07466440c37",
"org.opencontainers.image.licenses": "MIT"
},
"args": {
"DOCKER_META_IMAGES": "name/app",
"DOCKER_META_VERSION": "1.2.3"
}
}
}
}
```
## Customizing
### inputs
Following inputs can be used as `step.with` keys
> `List` type is a newline-delimited string
> ```yaml
> labels: |
> org.opencontainers.image.title=MyCustomTitle
> org.opencontainers.image.description=Another description
> org.opencontainers.image.vendor=MyCompany
> ```
| Name | Type | Description |
|---------------------|--------|----------------------------------------------------------|
| `images` | List | List of Docker images to use as base name for tags |
| `tags` | List | List of [tags](#tags-input) as key-value pair attributes |
| `flavor` | List | [Flavor](#flavor-input) to apply |
| `labels` | List | List of custom labels |
| `sep-tags` | String | Separator to use for tags output (default `\n`) |
| `sep-labels` | String | Separator to use for labels output (default `\n`) |
| `bake-target` | String | Bake target name (default `docker-metadata-action`) |
### outputs
Following outputs are available
| Name | Type | Description |
|---------------|---------|-------------------------------------------------------------------------------|
| `version` | String | Docker image version |
| `tags` | String | Docker tags |
| `labels` | String | Docker labels |
| `json` | String | JSON output of tags and labels |
| `bake-file` | File | [Bake definition file](https://github.com/docker/buildx#file-definition) path |
## `images` input
`images` defines a list of Docker images to use as base name for [`tags`](#tags-input):
```yaml
images: |
name/foo
ghcr.io/name/bar
# or
name=name/foo
name=ghcr.io/name/bar
```
Extended attributes and default values:
```yaml
images: |
name=,enable=true
```
* `name=<string>` image base name
* `enable=<true|false>` enable this entry (default `true`)
## `flavor` input
`flavor` defines a global behavior for [`tags`](#tags-input):
```yaml
flavor: |
latest=auto
prefix=
suffix=
```
* `latest=<auto|true|false>`: Handle [latest tag](#latest-tag) (default `auto`)
* `prefix=<string>,onlatest=<true|false>`: A global prefix for each generated tag and optionally for `latest`
* `suffix=<string>,onlatest=<true|false>`: A global suffix for each generated tag and optionally for `latest`
## `tags` input
`tags` is the core input of this action as everything related to it will reflect the output metadata. This one is in
the form of a key-value pair list in CSV format to remove limitations intrinsically linked to GitHub Actions
(only string format is handled in the input fields). Here is an example:
```yaml
tags: |
type=schedule
type=semver,pattern={{version}}
type=semver,pattern={{major}}.{{minor}}
type=semver,pattern={{major}}
type=ref,event=branch
type=ref,event=pr
type=sha
```
Each entry is defined by a `type`, which are:
* [`type=schedule`](#typeschedule)
* [`type=semver`](#typesemver)
* [`type=pep440`](#typepep440)
* [`type=match`](#typematch)
* [`type=edge`](#typeedge)
* [`type=ref`](#typeref)
* [`type=raw`](#typeraw)
* [`type=sha`](#typesha)
And global attributes:
* `enable=<true|false>` enable this entry (default `true`)
* `priority=<number>` priority to manage the order of tags
* `prefix=<string>` add prefix
* `suffix=<string>` add suffix
Default entries if `tags` input is empty:
```yaml
tags: |
type=schedule
type=ref,event=branch
type=ref,event=tag
type=ref,event=pr
```
### `type=schedule`
```yaml
tags: |
# minimal
type=schedule
# default
type=schedule,pattern=nightly
# handlebars
type=schedule,pattern={{date 'YYYYMMDD'}}
```
Will be used on [schedule event](https://docs.github.com/en/actions/reference/events-that-trigger-workflows#schedule).
`pattern` is a specially crafted attribute to support [Handlebars' template](https://handlebarsjs.com/guide/) with
the following expressions:
* `date 'format'` ; render date by its [moment format](https://momentjs.com/docs/#/displaying/format/)
| Pattern | Output |
|--------------------------|----------------------|
| `nightly` | `nightly` |
| `{{date 'YYYYMMDD'}}` | `20210326` |
Extended attributes and default values:
```yaml
tags: |
type=schedule,enable=true,priority=1000,prefix=,suffix=,pattern=nightly
```
### `type=semver`
```yaml
tags: |
# minimal
type=semver,pattern={{version}}
# use custom value instead of git tag
type=semver,pattern={{version}},value=v1.0.0
```
Will be used on a [push tag event](https://docs.github.com/en/actions/reference/events-that-trigger-workflows#push)
and requires a valid [semver](https://semver.org/) Git tag, but you can also use a custom value through `value`
attribute.
`pattern` attribute supports [Handlebars template](https://handlebarsjs.com/guide/) with the following expressions:
* `raw` ; the actual tag
* `version` ; shorthand for `{{major}}.{{minor}}.{{patch}}` (can include pre-release)
* `major` ; major version identifier
* `minor` ; minor version identifier
* `patch` ; patch version identifier
| Git tag | Pattern | Output |
|--------------------|----------------------------------------------------------|----------------------|
| `v1.2.3` | `{{raw}}` | `v1.2.3` |
| `v1.2.3` | `{{version}}` | `1.2.3` |
| `v1.2.3` | `{{major}}.{{minor}}` | `1.2` |
| `v1.2.3` | `v{{major}}` | `v1` |
| `v1.2.3` | `{{minor}}` | `2` |
| `v1.2.3` | `{{patch}}` | `3` |
| `v2.0.8-beta.67` | `{{raw}}` | `v2.0.8-beta.67` |
| `v2.0.8-beta.67` | `{{version}}` | `2.0.8-beta.67` |
| `v2.0.8-beta.67` | `{{major}}.{{minor}}` | `2.0.8-beta.67`* |
> *Pre-release (rc, beta, alpha) will only extend `{{version}}` (or `{{raw}}` if specified) as tag
> because they are updated frequently, and contain many breaking changes that are (by the author's design)
> not yet fit for public consumption.
Extended attributes and default values:
```yaml
tags: |
type=semver,enable=true,priority=900,prefix=,suffix=,pattern=,value=
```
### `type=pep440`
```yaml
tags: |
# minimal
type=pep440,pattern={{version}}
# use custom value instead of git tag
type=pep440,pattern={{version}},value=1.0.0
```
Will be used on a [push tag event](https://docs.github.com/en/actions/reference/events-that-trigger-workflows#push)
and requires a Git tag that conforms to [PEP 440](https://www.python.org/dev/peps/pep-0440/), but you can also use a
custom value through `value` attribute.
`pattern` attribute supports [Handlebars template](https://handlebarsjs.com/guide/) with the following expressions:
* `raw` ; the actual tag
* `version` ; cleaned version
* `major` ; major version identifier
* `minor` ; minor version identifier
* `patch` ; patch version identifier
| Git tag | Pattern | Output |
|--------------------|----------------------------------------------------------|----------------------|
| `1.2.3` | `{{raw}}` | `1.2.3` |
| `1.2.3` | `{{version}}` | `1.2.3` |
| `v1.2.3` | `{{version}}` | `1.2.3` |
| `1.2.3` | `{{major}}.{{minor}}` | `1.2` |
| `1.2.3` | `v{{major}}` | `v1` |
| `v1.2.3rc2` | `{{raw}}` | `v1.2.3rc2` |
| `1.2.3rc2` | `{{version}}` | `1.2.3rc2` |
| `1.2.3rc2` | `{{major}}.{{minor}}` | `1.2.3rc2`* |
| `1.2.3post1` | `{{major}}.{{minor}}` | `1.2.3.post1`* |
| `1.2.3beta2` | `{{major}}.{{minor}}` | `1.2.3b2`* |
| `1.0dev4` | `{{major}}.{{minor}}` | `1.0.dev4`* |
> *dev/pre/post release will only extend `{{version}}` (or `{{raw}}` if specified) as tag
> because they are updated frequently, and contain many breaking changes that are (by the author's design)
> not yet fit for public consumption.
Extended attributes and default values:
```yaml
tags: |
type=pep440,enable=true,priority=900,prefix=,suffix=,pattern=,value=
```
### `type=match`
```yaml
tags: |
# minimal
type=match,pattern=\d.\d.\d
# define match group
type=match,pattern=v(.*),group=1
# use custom value instead of git tag
type=match,pattern=v(.*),group=1,value=v1.0.0
```
Can create a regular expression for matching Git tag with a pattern and capturing group. Will be used on a
[push tag event](https://docs.github.com/en/actions/reference/events-that-trigger-workflows#push) but, you can also use
a custom value through `value` attribute.
| Git tag | Pattern | Group | Output |
|-------------------------|-------------------------------|---------|------------------------|
| `v1.2.3` | `\d.\d.\d` | `0` | `1.2.3` |
| `v2.0.8-beta.67` | `v(.*)` | `1` | `2.0.8-beta.67` |
| `v2.0.8-beta.67` | `v(\d.\d)` | `1` | `2.0` |
| `20200110-RC2` | `\d+` | `0` | `20200110` |
| `p1/v1.2.3` | `p1-v(\d.\d.\d)` | `1` | `1.2.3` |
Extended attributes and default values:
```yaml
tags: |
type=match,enable=true,priority=800,prefix=,suffix=,pattern=,group=0,value=
```
### `type=edge`
```yaml
tags: |
# minimal
type=edge
# define default branch
type=edge,branch=main
```
An `edge` tag reflects the last commit of the active branch on your Git repository. I usually prefer to use `edge`
as a Docker tag for a better distinction or common pattern. This is also used by official images
like [Alpine](https://hub.docker.com/_/alpine).
Extended attributes and default values:
```yaml
tags: |
type=edge,enable=true,priority=700,prefix=,suffix=,branch=$repo.default_branch
```
### `type=ref`
```yaml
tags: |
# branch event
type=ref,event=branch
# tag event
type=ref,event=tag
# pull request event
type=ref,event=pr
```
This type handles Git ref (or reference) for the following events:
* `branch` ; eg. `refs/heads/master`
* `tag` ; eg. `refs/tags/v1.0.0`
* `pr` ; eg. `refs/pull/318/merge`
| Event | Ref | Output |
|-----------------|-------------------------------|-------------------------------|
| `pull_request` | `refs/pull/2/merge` | `pr-2` |
| `push` | `refs/heads/master` | `master` |
| `push` | `refs/heads/my/branch` | `my-branch` |
| `push tag` | `refs/tags/v1.2.3` | `v1.2.3` |
| `push tag` | `refs/tags/v2.0.8-beta.67` | `v2.0.8-beta.67` |
Extended attributes and default values:
```yaml
tags: |
# branch event
type=ref,enable=true,priority=600,prefix=,suffix=,event=branch
# tag event
type=ref,enable=true,priority=600,prefix=,suffix=,event=tag
# pull request event
type=ref,enable=true,priority=600,prefix=pr-,suffix=,event=pr
```
### `type=raw`
```yaml
tags: |
type=raw,value=foo
type=raw,value=bar
# or
type=raw,foo
type=raw,bar
# or
foo
bar
```
Output custom tags according to your needs.
Extended attributes and default values:
```yaml
tags: |
type=raw,enable=true,priority=200,prefix=,suffix=,value=
```
### `type=sha`
```yaml
tags: |
# minimal (short sha)
type=sha
# full length sha
type=sha,format=long
```
Output Git short commit (or long if specified) as Docker tag like `sha-ad132f5`.
Extended attributes and default values:
```yaml
tags: |
type=sha,enable=true,priority=100,prefix=sha-,suffix=,format=short
```
## Notes
### Latest tag
`latest` tag is handled through the [`flavor` input](#flavor-input). It will be generated by default (`auto` mode) for:
* [`type=ref,event=tag`](#typeref)
* [`type=semver,pattern=...`](#typesemver)
* [`type=match,pattern=...`](#typematch)
For conditionally tagging with latest for a specific branch name, e.g. if your
default branch name is not `master`, use `type=raw` with a boolean expression:
```yaml
tags: |
# set latest tag for master branch
type=raw,value=latest,enable=${{ github.ref == format('refs/heads/{0}', 'master') }}
```
You can also use the [`{{is_default_branch}}` global expression](#is_default_branch)
to conditionally tag with latest for the default branch:
```yaml
tags: |
# set latest tag for default branch
type=raw,value=latest,enable={{is_default_branch}}
```
### Global expressions
The following [Handlebars' template](https://handlebarsjs.com/guide/) expressions
for `prefix`, `suffix`, `value` and `enable` attributes are available:
```yaml
tags: |
# dynamically set the branch name as a prefix
type=sha,prefix={{branch}}-
# dynamically set the branch name and sha as a custom tag
type=raw,value=mytag-{{branch}}-{{sha}}
```
#### `{{branch}}`
Returns the branch name that triggered the workflow run. Will be empty if not
a branch reference:
| Event | Ref | Output |
|-----------------|-------------------------------|---------------------|
| `pull_request` | `refs/pull/2/merge` | |
| `push` | `refs/heads/master` | `master` |
| `push` | `refs/heads/my/branch` | `my-branch` |
| `push tag` | `refs/tags/v1.2.3` | |
#### `{{tag}}`
Returns the tag name that triggered the workflow run. Will be empty if not a
tag reference:
| Event | Ref | Output |
|-----------------|-------------------------------|--------------------|
| `pull_request` | `refs/pull/2/merge` | |
| `push` | `refs/heads/master` | |
| `push` | `refs/heads/my/branch` | |
| `push tag` | `refs/tags/v1.2.3` | `v1.2.3` |
#### `{{sha}}`
Returns the short commit SHA that triggered the workflow run (e.g., `90dd603`).
#### `{{base_ref}}`
Returns the base ref or target branch of the pull request that triggered the
workflow run. Will be empty for a branch reference:
| Event | Ref | Output |
|----------------|-------------------------------|--------------------|
| `pull_request` | `refs/pull/2/merge` | `master` |
| `push` | `refs/heads/master` | |
| `push` | `refs/heads/my/branch` | |
| `push tag`* | `refs/tags/v1.2.3` | `master` |
> *`base_ref` is available in the push payload but doesn't always seem to
> return the expected branch when the push tag event occurs. It's also
> [not documented in GitHub docs](https://docs.github.com/en/developers/webhooks-and-events/webhooks/webhook-events-and-payloads#push).
> We keep it for backward compatibility, but it's **not recommended relying on it**.
> More context in [#192](https://github.com/docker/metadata-action/pull/192#discussion_r854673012).
#### `{{is_default_branch}}`
Returns `true` if the branch that triggered the workflow run is the default
one, otherwise `false`.
#### `{{date '<format>'}}`
Returns the current date rendered by its [moment format](https://momentjs.com/docs/#/displaying/format/).
| Expression | Output example |
|--------------------------------------------|-----------------------------------------|
| `{{date 'YYYYMMDD'}}` | `20200110` |
| `{{date 'dddd, MMMM Do YYYY, h:mm:ss a'}}` | `Friday, January 10th 2020, 3:25:50 pm` |
### Major version zero
Major version zero (`0.y.z`) is for initial development and **may** change at any time. This means the public API
[**should not** be considered stable](https://semver.org/#spec-item-4).
In this case, Docker tag `0` **should not** be generated if you're using [`type=semver`](#typesemver) with `{{major}}`
pattern. You can manage this behavior like this:
```yaml
# refs/tags/v0.1.2
tags: |
# output 0.1.2
type=semver,pattern={{version}}
# output 0.1
type=semver,pattern={{major}}.{{minor}}
# disabled if major zero
type=semver,pattern={{major}},enable=${{ !startsWith(github.ref, 'refs/tags/v0.') }}
```
### JSON output object
The `json` output is a JSON object composed of the generated tags and labels so that you can reuse them further in your
workflow using the [`fromJSON` function](https://docs.github.com/en/actions/learn-github-actions/expressions#fromjson):
```yaml
-
name: Docker meta
uses: docker/metadata-action@v3
id: meta
with:
images: name/app
-
name: Build and push
uses: docker/build-push-action@v2
with:
tags: ${{ steps.meta.outputs.tags }}
labels: ${{ steps.meta.outputs.labels }}
build-args: |
BUILDTIME=${{ fromJSON(steps.meta.outputs.json).labels['org.opencontainers.image.created'] }}
VERSION=${{ fromJSON(steps.meta.outputs.json).labels['org.opencontainers.image.version'] }}
REVISION=${{ fromJSON(steps.meta.outputs.json).labels['org.opencontainers.image.revision'] }}
```
### Overwrite labels
If some [OCI Image Format Specification](https://github.com/opencontainers/image-spec/blob/master/annotations.md)
labels generated are not suitable, you can overwrite them like this:
```yaml
-
name: Docker meta
id: meta
uses: docker/metadata-action@v3
with:
images: name/app
labels: |
maintainer=CrazyMax
org.opencontainers.image.title=MyCustomTitle
org.opencontainers.image.description=Another description
org.opencontainers.image.vendor=MyCompany
```
## Keep up-to-date with GitHub Dependabot
Since [Dependabot](https://docs.github.com/en/github/administering-a-repository/keeping-your-actions-up-to-date-with-github-dependabot)
has [native GitHub Actions support](https://docs.github.com/en/github/administering-a-repository/configuration-options-for-dependency-updates#package-ecosystem),
to enable it on your GitHub repo all you need to do is add the `.github/dependabot.yml` file:
```yaml
version: 2
updates:
# Maintain dependencies for GitHub Actions
- package-ecosystem: "github-actions"
directory: "/"
schedule:
interval: "daily"
```