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Update Version in variables or buildargs in Dockerfiles with Renovatebot

My team is using Renovatebot for automatic dependency management and is quite happy with it.

Renovate can manage a bunch of dependencies out of the box:

  • Tags and Digests of Docker images
  • Refs of GitLab Include directives
  • Ansible Collections / Roles
  • Helm Charts
  • Python packages
  • and more…

However, we have some versions in a Dockerfile which we use for downloading packages during the build process:

FROM alpine:3.14.0@sha256:234cb88d3020898631af0ccbbcca9a66ae7306ecd30c9720690858c1b007d2a0

ARG KUBECTL_VERSION=1.21.1

RUN wget -q -O /usr/local/bin/kubectl https://storage.googleapis.com/kubernetes-release/release/v${KUBECTL_VERSION}/bin/linux/amd64/kubectl && \
    chmod 0755 /usr/local/bin/kubectl

The KUBECTL_VERSION variable isn’t picked up by Renovatebot automatically, as it has no way of knowing which package this variable references. However you can use the regex manager in the .renovate.json file to provide some context.

The Renovatebot documentation actually provides an example how to achieve this. However, we needed some further customization:

  • ability to remove the v from tags on github (e.g. v1.2.3 -> 1.2.3).
  • support for ARG and ENV keyword

We came up with the following solution which can be added to the .renovate.json:

{
  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
  "regexManagers": [
    {
      "fileMatch": [
        "(^|/)Dockerfile$",
        "(^|/)Dockerfile\\.[^/]*$"
      ],
      "matchStrings": [
        "#\\srenovate:\\sdatasource=(?<datasource>.*?) depName=(?<depName>.*?)( versioning=(?<versioning>.*?))?( extractVersion=(?<extractVersion>.*?))?\\s(ENV|ARG) .*?_VERSION=(?<currentValue>.*)\\s"
      ]
    }
  ]
}

Using the snippet above, renovate will be able to manage the version of the variable(s) in the Dockerfile, just by adding a special comment in front of the ARG/ENV statement:

FROM alpine:3.14.0@sha256:234cb88d3020898631af0ccbbcca9a66ae7306ecd30c9720690858c1b007d2a0

# renovate: datasource=github-releases depName=kubernetes/kubernetes extractVersion=^v(?<version>.*)$
ARG KUBECTL_VERSION=1.21.1

RUN wget -q -O /usr/local/bin/kubectl https://storage.googleapis.com/kubernetes-release/release/v${KUBECTL_VERSION}/bin/linux/amd64/kubectl && \
    chmod 0755 /usr/local/bin/kubectl
2021-06-17
/update-version-in-variables-or-buildargs-in-dockerfiles-with-renovatebot/ Stefan Hojer