Docs: Update autoscale AWS documentation that still uses deprecated docker+machine executor

Problem to solve

The documentation page "Autoscale GitLab Runner on AWS" at:

https://docs.gitlab.com/runner/configuration/runner_autoscale_aws/

is outdated and still instructs users to use the docker+machine executor.

However:

• The docker-machine project is archived and unmaintained (https://github.com/docker/machine).
• GitLab Runner’s docker+machine executor is officially deprecated and will be removed in a future release: https://docs.gitlab.com/runner/executors/docker_machine/
• GitLab Runner documentation recommends the Instance Group Autoscaler as the replacement: https://docs.gitlab.com/runner/runner_autoscale/gitlab-runner-autoscaler/

This creates confusion for users because the linked doc appears to describe a recommended autoscaling method, but in reality it relies entirely on deprecated and unsupported components.

Further details

Users following this document will attempt to configure autoscaling runners with docker+machine. This leads to:

• Compatibility errors (for example Docker API mismatches such as client version 1.43 is too old)
• Instability when creating AWS instances
• Unsupported docker-machine behaviors
• An autoscaling method that GitLab no longer recommends or maintains

GitLab now has a modern and fully supported solution for autoscaling runners on AWS:
the GitLab Runner Autoscaler (Instance Group Autoscaler).

Updating the documentation will prevent new users from adopting a deprecated architecture and guide them toward the supported solution.

Target audience:

• DevOps engineers deploying autoscaled GitLab Runners on AWS
• Cloud infrastructure teams following GitLab documentation

Proposal

• Add a clear deprecation notice at the top of https://docs.gitlab.com/runner/configuration/runner_autoscale_aws/ indicating that docker+machine is deprecated and will be removed.

• Replace or rewrite the page to recommend:

  • GitLab Runner Autoscaler (Instance Group Autoscaler)
    https://docs.gitlab.com/runner/runner_autoscale/gitlab-runner-autoscaler/

• Update examples, diagrams, and instructions to reflect the current best practice.

• Optionally provide a migration path for users moving from docker+machine to the new autoscaler.

Who can address the issue

A technical writer in collaboration with the Runner team or compute/infra specialists familiar with autoscaling architecture.

Other links/references

• Docker Machine archived: https://github.com/docker/machine

• Docker Machine executor deprecated: https://docs.gitlab.com/runner/executors/docker_machine/

• GitLab issue: Remove docker+machine executor gitlab-runner#29086 (closed)