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 files
• CircleCI config files
• Kubernetes manifests
• Ansible configuration files

How It Works

1. Renovate will search each repository for any files matching each manager's configured fileMatch pattern(s)
2. Files that match the pattern(s) are parsed and checked to see if they contain any Docker image references (e.g. FROM lines in a Dockerfile)
3. If the image tag in use "looks" like a semver (e.g. node:12, node:12.1, node:12.1.0, node:12-onbuild) then Renovate will look up the Docker registry to determine if any upgrades are available (e.g. node:12.2.0).

Preservation of Version Precision

Renovate by default will preserve the precision of Docker images. For example if the existing image is node:12.1 then Renovate would only propose upgrades to node:12.2 or node:12.3 and not to more specified versions like node:12.2.0 or node:12.3.0. Renovate does not yet support "pinning" an imprecise version to a precise version, e.g. from node:12.2 to node:12.2.0, 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. 12.2.0-alpine. Renovate defaults to assuming suffixes indicate compatibility so will never change it. e.g. 12.1.0-alpine might get updated to 12.1.1-alpine but never 12.1.1 or 12.1.1-stretch.

If this behaviour does not suit a particular package you have, Renovate allows you to customize the versioning in use. For example, if you have a Docker image foo/bar that sticks to semver versioning and you need Renovate to understand that suffixes indicate pre-releases versions and not compatibility, then you could configure this package rule:

{
  "packageRules": [
    {
      "datasources": ["docker"],
      "packageNames": ["foo/bar"],
      "versioning": "semver"
    }
  ]
}

Another example is the official python image, which follows pep440 versioning. You can configure that with another package rule:

{
  "packageRules": [
    {
      "datasources": ["docker"],
      "packageNames": ["python"],
      "versioning": "pep440"
    }
  ]
}

If traditional versioning doesn't work, consider using Renovate's built-in loose versioning. It essentially just does a best effort sort of versions, regardless of whether they contain letters or digits.

Finally, if you use a Docker image that follows a versioning approach not captured by one of our existing versionings, and which loose sorts incorrectly, you could see if the regex versioning can work. It uses regex capture group syntax to let you specify which part of the version string is major, minor, patch, pre-release, or compatibility. See the docs for versioning for documentation/examples of regex versioning in action.

Digest Pinning

Pinning your docker images to an exact digest is recommended for reasons of immutability. In short: pin to digests so every time you pull, you get the same content.

If your experience with dependency versioning comes from a place like javascript/npm, you might be used to exact versions being immutable, e.g. if you specify a version like 2.0.1 then you and your colleagues will always get the exact same "code". What you may not expect is that Docker's tags are not immutable versions even if they look like a version. e.g. you probably expect that node:8 and node:8.9 will change over time, but you might incorrectly assume that node:8.9.0 would never change. 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 docker tag will achieve immutability but as a human it's quite inconvenient to deal with strings like FROM node@sha256:552348163f074034ae75643c01e0ba301af936a898d778bb4fc16062917d0430. The good news is that, as a human you no longer need to manually update such digests once you have Renovate on the job.

Also, to retain some human-friendliness, Renovate will actually retain the tag in the FROM line too, e.g. FROM node:8@sha256:552348163f074034ae75643c01e0ba301af936a898d778bb4fc16062917d0430. Read on to see how Renovate keeps it up-to-date.

Digest Updating

If you have followed our advice to go from tags like node:8 to node:8@sha256:552348163f074034ae75643c01e0ba301af936a898d778bb4fc16062917d0430, then you are likely to receive Renovate PRs whenever the node:8 image is updated on Docker Hub.

Previously this would have been "invisible" to you - one day you pull code that represents node:8.9.0 and the next day you get node:8.9.1. But you can never be sure, especially as Docker caches. Perhaps some of your colleagues or worst still your build machine are stuck on an older version with a security vulnerability.

Instead, you will now receive these updates via Pull Requests, or perhaps committed directly to your repository if you enable branch automerge for convenience. This ensures everyone on the team gets the latest versions and is in sync.

Version Upgrading

Renovate also supports upgrading versions in Docker tags, e.g. from node:8.9.0 to node:8.9.1 or node:8.9 to node:8.10. If your tags looks like a version, Renovate will upgrade it like a version.

Thanks to this, you may wish to change the way you tag your image dependencies to be more specific, e.g. change from node:8 to node:8.9.1 so that every Renovate PR will be more human friendly, e.g. you can know that you are getting a PR because node upgraded from 8.9.1 to 8.9.2 and not because 8.9.1 somehow changed.

Currently, Renovate will upgrade minor/patch versions (e.g. from 8.9.0 to 8.9.1) 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 a 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. Note though that this is not foolproof, because some managers like circleci and ansible support multiple datasources so 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 add 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. Also add "default:automergeBranchPush" if you wish for these to be committed directly to your base branch without raising a PR first.

Registry authentication

Here is an example of configuring a default Docker username/password in config.js:

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

It is possible to add additional host rules following the documentation. For example if you have some images you host yourself that are password protected and also some images you pull from docker hub without authentication then you can configure for a specific Docker host like this:

module.exports = {
  hostRules: [
    {
      hostType: 'docker',
      hostName: 'your.host.io',
      username: '<your-username>',
      password: '<your-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);