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Custom Manager Support using Regex

The regex manager is designed to allow users to manually configure Renovate for how to find dependencies that aren't detected by the built-in package managers.

This manager is unique in Renovate in that:

  • It is configurable via regex named capture groups
  • Through the use of the regexManagers config, multiple "regex managers" can be created for the same repository.

Required Fields

The first two required fields are fileMatch and matchStrings. fileMatch works the same as any manager, while matchStrings is a regexManagers concept and is used for configuring a regular expression with named capture groups.

In order for Renovate to look up a dependency and decide about updates, it then needs the following information about each dependency:

  • The dependency's name
  • Which datasource to look up (e.g. npm, Docker, GitHub tags, etc)
  • Which version scheme to apply (defaults to semver, but also may be other values like pep440)

Configuration-wise, it works like this:

  • You must capture the currentValue of the dependency in a named capture group
  • You must have either a depName capture group or a depNameTemplate config field
  • You can optionally have a lookupName capture group or a lookupNameTemplate if it differs from depName
  • You must have either a datasource capture group or a datasourceTemplate config field
  • You can optionally have a versioning capture group or a versioningTemplate config field. If neither are present, semver will be used as the default
  • You can optionally have a currentDigest capture group.

Regular Expression Capture Groups

To be fully effective with the regex manager, you will need to understand regular expressions and named capture groups, although sometimes enough examples can compensate for lack of experience.

Consider this Dockerfile:

FROM node:12
ENV YARN_VERSION=1.19.1
RUN curl -o- -L https://yarnpkg.com/install.sh | bash -s -- --version ${YARN_VERSION}

You would need to capture the currentValue using a named capture group, like so: ENV YARN_VERSION=(?<currentValue>.*?)\n.

If you're looking for an online regex testing tool that supports capture groups, try https://regex101.com/.

Configuration templates

In many cases, named capture groups alone won't be enough and you'll need to configure Renovate with additional information about how to look up a dependency. Continuing the above example with Yarn, here is the full config:

{
  "regexManagers": [
    {
      "fileMatch": ["^Dockerfile$"],
      "matchStrings": ["ENV YARN_VERSION=(?<currentValue>.*?)\n"],
      "depNameTemplate": "yarn",
      "datasourceTemplate": "npm"
    }
  ]
}

Advanced Capture

Let's say that your Dockerfile has many ENV variables you want to keep updated and you prefer not to write one regexManagers rule per variable. Instead you could enhance your Dockerfile like the following:

ARG IMAGE=node:12@sha256:6e5264cd4cfaefd7174b2bc10c7f9a1c2b99d98d127fc57a802d264da9fb43bd
FROM ${IMAGE}
 # renovate: datasource=github-tags depName=nodejs/node versioning=node
ENV NODE_VERSION=10.19.0
 # renovate: datasource=github-releases depName=composer/composer
ENV COMPOSER_VERSION=1.9.3
# renovate: datasource=docker depName=docker versioning=docker
ENV DOCKER_VERSION=19.03.1
# renovate: datasource=npm depName=yarn
ENV YARN_VERSION=1.19.1

The above (obviously not a complete Dockerfile, but abbreviated for this example), could then be supported accordingly:

{
  "regexManagers": [
    {
      "fileMatch": ["^Dockerfile$"],
      "matchStrings": [
        "datasource=(?<datasource>.*?) depName=(?<depName>.*?)( versioning=(?<versioning>.*?))?\\sENV .*?_VERSION=(?<currentValue>.*)\\s"
      ],
      "versioningTemplate": "{{#if versioning}}{{versioning}}{{else}}semver{{/if}}"
    },
    {
      "fileMatch": ["^Dockerfile$"],
      "matchStrings": [
        "ARG IMAGE=(?<depName>.*?):(?<currentValue>.*?)@(?<currentDigest>sha256:[a-f0-9]+)s"
      ],
      "datasourceTemplate": "docker"
    }
  ]
}

In the above the versioningTemplate is not actually necessary because Renovate already defaults to semver versioning, but it has been included to help illustrate why we call these fields templates. They are named this way because they are compiled using handlebars and so can be composed from values you collect in named capture groups.

By adding the comments to the Dockerfile, you can see that instead of four separate regexManagers being required, there is now only one - and the Dockerfile itself is now somewhat better documented too. The syntax we used there is completely arbitrary and you may choose your own instead if you prefer - just be sure to update your matchStrings regex.