renovate/docs/usage/docker.md

title	description
Docker	Docker Package Manager Support in Renovate

Docker

Renovate supports upgrading dependencies in various types of Docker definition files:

• Docker's Dockerfile files
• Docker Compose docker-compose.yml files
• CircleCI config files
• Kubernetes manifest files
• Ansible configuration files

How It Works

1. Renovate searches in each repository for any files matching each manager's configured fileMatch pattern(s)
2. Matching files are parsed, Renovate checks if the file(s) contain any Docker image references (e.g. FROM lines in a Dockerfile)
3. If the image tag in use "looks" like a version (e.g. myimage:1, myimage:1.1, myimage:1.1.0, myimage:1-onbuild) then Renovate checks the Docker registry for upgrades (e.g. from myimage:1.1.0 to myimage:1.2.0)

Preservation of Version Precision

By default, Renovate preserves the precision level specified in the Docker images. For example, if the existing image is pinned at myimage:1.1 then Renovate only proposes upgrades to myimage:1.2 or myimage:1.3. This means that you will not get upgrades to a more specific versions like myimage:1.2.0 or myimage:1.3.0. Renovate does not yet support "pinning" an imprecise version to a precise version, e.g. from myimage:1.2 to myimage:1.2.0, however it's a feature we'd like to implement one day.

Version compatibility

Although suffixes in SemVer indicate pre-releases (e.g. v1.2.0-alpha.2), in Docker they typically indicate compatibility, e.g. 1.2.0-alpine. By default Renovate assumes suffixes indicate compatibility, for this reason Renovate will not change any suffixes. Renovate will update 1.2.0-alpine to 1.2.1-alpine but never updates to 1.2.1 or 1.2.1-stretch as that would change the suffix.

If this behavior does not suit a particular package you have, Renovate allows you to customize the versioning scheme it uses. For example, you have a Docker image foo/bar that sticks to SemVer versioning. This means that you need to tell Renovate that suffixes indicate pre-release versions, and not compatibility.

You could then use this packageRules array, to tell Renovate to use semver versioning for the foo/bar package:

{
  "packageRules": [
    {
      "matchDatasources": ["docker"],
      "matchPackageNames": ["foo/bar"],
      "versioning": "semver"
    }
  ]
}

Another example is the official python image, which follows pep440 versioning. You can tell Renovate to use the pep440 versioning scheme with this set of packageRules:

{
  "packageRules": [
    {
      "matchDatasources": ["docker"],
      "matchPackageNames": ["python"],
      "versioning": "pep440"
    }
  ]
}

If traditional versioning doesn't work, try Renovate's built-in loose versioning. Renovate will perform a best-effort sort of the versions, regardless of whether they contain letters or digits.

If both the traditional versioning, and the loose versioning do not give the results you want, try the regex versioning. This approach uses regex capture group syntax to specify which part of the version string is major, minor, patch, pre-release, or compatibility. See the docs for versioning for documentation and examples of regex versioning in action.

Digest Pinning

We recommend that you pin your Docker images to an exact digest. By pinning to a digest you ensure your Docker builds are immutable: every time you do a pull you get the same content.

If you have experience with the way dependency versioning is handled in the JavaScript/npm ecosystem, you might be used to exact versions being immutable. e.g. if you specify a version like 2.0.1, you and your colleagues always get the exact same "code".

What you may not know is that Docker's tags are not immutable versions, even if they look like a version. e.g. you probably expect myimage:1 and myimage:1.2 to change over time, but you might incorrectly assume that myimage:1.2.0 never changes. Although it probably shouldn't, the reality is that any Docker image tag can change content, and potentially break.

Using a Docker digest as the image's primary identifier instead of using a Docker tag will achieve immutability. It's not easy to work with strings like FROM node@sha256:d938c1761e3afbae9242848ffbb95b9cc1cb0a24d889f8bd955204d347a7266e. Luckily Renovate can update the digests for you, so you don't have to.

To keep things simple, Renovate retains the Docker tag in the FROM line, e.g. FROM node:14.15.1@sha256:d938c1761e3afbae9242848ffbb95b9cc1cb0a24d889f8bd955204d347a7266e. Read on to see how Renovate updates Docker digests.

Digest Updating

If you follow our advice to go from a simple tag like node:14 to using a pinned digest node:14@sha256:d938c1761e3afbae9242848ffbb95b9cc1cb0a24d889f8bd955204d347a7266e, you will receive Renovate PRs whenever the node:14 image is updated on Docker Hub.

Previously this update would have been "invisible" to you - one day you pull code that represents node:14.15.0 and the next day you get code that represents node:14.15.1. But you can never be sure, especially as Docker caches. Perhaps some of your colleagues or worse still your build machine are stuck on an older version with a security vulnerability.

By pinning to a digest instead, you will receive these updates via Pull Requests, or even committed directly to your repository if you enable branch automerge for convenience. This ensures everyone on the team uses the latest versions and is in sync.

Version Upgrading

Renovate also supports upgrading versions in Docker tags, e.g. from myimage:1.2.0 to myimage:1.2.1 or myimage:1.2 to myimage:1.3. If a tag looks like a version, Renovate will upgrade it like a version.

We recommend you use the major.minor.patch tagging scheme e.g. change from myimage:1 to myimage:1.1.1. This way it's easy to see what the Renovate PR is going to change. You can see the difference between a PR that upgrades myimage from 1.1.1 to 1.1.2. and a PR that changes the contents of the version you already use (1.1.1).

Currently, Renovate will upgrade minor/patch versions (e.g. from 1.2.0 to 1.2.1) by default, but not upgrade major versions. If you wish to enable major versions then add the preset docker:enableMajor to your extends array in your renovate.json.

Renovate has some Docker-specific intelligence when it comes to versions. For example:

Configuring/Disabling

If you wish to make changes that apply to all Docker managers, then add them to the docker config object. This is not foolproof, because some managers like circleci and ansible support multiple datasources that do not inherit from the docker config object.

If you wish to override Docker settings for one particular type of manager, use that manager's config object instead. For example, to disable digest updates for Docker Compose only but leave them for other managers like Dockerfile, you would use this:

  "docker-compose": {
    "digest": {
      "enabled": false
    }
  }

The following configuration options are applicable to Docker:

Disable all Docker Renovation

Add "docker:disable" to your extends array.

Disable Renovate for only certain Dockerfiles

Add all paths to ignore into the ignorePaths configuration field. e.g.

{
  "extends": ["config:base"],
  "ignorePaths": ["docker/old-files/"]
}

Enable Docker major updates

Add "docker:enableMajor" to your extends array.

Disable digest pinning

Add "default:pinDigestsDisabled" to your extends array.

Automerge digest updates

Add "default:automergeDigest" to your extends array. If you want Renovate to commit directly to your base branch without opening a PR first, add "default:automergeBranchPush" to the extends array.

Registry authentication

There are many different registries, and many ways to authenticate to those registries. We will explain how to authenticate for the most common registries.

DockerHub

Here is an example of configuring a default Docker username/password in config.js. The Docker Hub password is stored in a process environment variable.

module.exports = {
  hostRules: [
    {
      hostType: 'docker',
      username: '<your-username>',
      password: process.env.DOCKER_HUB_PASSWORD,
    },
  ],
};

You can add additional host rules, read the hostrules documentation for more information.

Self-hosted Docker registry

Say you host some Docker images yourself, and use a password to access your self-hosted Docker images. In addition to self-hosting, you also pull images from Docker Hub, without a password. In this example you would configure a specific Docker host like this:

module.exports = {
  hostRules: [
    {
      hostType: 'docker',
      hostName: 'your.host.io',
      username: '<your-username>',
      password: process.env.SELF_HOSTED_DOCKER_IMAGES_PASSWORD,
    },
  ],
};

ChartMuseum

Maybe you're running your own ChartMuseum server to host your private Helm Charts. This is how you connect to a private Helm repository:

module.exports = {
  hostRules: [
    {
      hostName: 'your.host.io',
      username: '<your-username>',
      password: process.env.SELF_HOSTED_HELM_CHARTS_PASSWORD,
    },
  ],
};

If you need to configure per-repository credentials then you can also configure the above within a repository's Renovate config (e.g. renovate.json).