Missing documentation on how to update to 10.0.0

Summary

I can't find any documentation on how to update from gitlab-ci-multi-runner to gitlab-runner.

On the installation page there's an update section, but it just has instructions for updating gitlab-ci-multi-runner OR gitlab-runner, but not for updating from gitlab-ci-multi-runner TO gitlab-runner.

I tried to simply remove gitlab-ci-multi-runner and install gitlab-runner (see steps to reproduce), but this results in some messages I'm not really comfortable with. Why does it just say "service is not installed"?

It seems to be working (version 10.0.0 is showing for this runner in the GitLab UI), but I would appreciate it if there was an official guide on how to update (also for Windows).

Steps to reproduce

1. apt remove gitlab-ci-multi-runner
2. Change the repository from https://packages.gitlab.com/runner/gitlab-ci-multi-runner/ubuntu/ to https://packages.gitlab.com/runner/gitlab-runner/ubuntu/
3. apt update
4. apt install gitlab-runner

Relevant logs and/or screenshots

Preparing to unpack .../gitlab-runner_10.0.0_amd64.deb ...
Unpacking gitlab-runner (10.0.0) ...
Setting up gitlab-runner (10.0.0) ...
GitLab Runner: detected user gitlab-runner
WARNING: Since GitLab Runner 10.0 this command is marked as DEPRECATED and will be removed in one of the upcoming releases
gitlab-runner: Service is not installed.
WARNING: Since GitLab Runner 10.0 this command is marked as DEPRECATED and will be removed in one of the upcoming releases
gitlab-ci-multi-runner: Service is not installed.
WARNING: Since GitLab Runner 10.0 this command is marked as DEPRECATED and will be removed in one of the upcoming releases
WARNING: Since GitLab Runner 10.0 this command is marked as DEPRECATED and will be removed in one of the upcoming releases

Environment description

GitLab Runner on Ubuntu Xenial.

Used GitLab Runner version

From 9.5.0 to 10.0.0.

According to the post-install script I guess this is what happens:

1. L6-11: check if the gitlab-runner user already exists so the existing user can be reused. Just an informational message.

    GitLab Runner: detected user gitlab-runner

2. L37-40: check if the gitlab-runner service already exists. The warning is generated because of #2710 (closed). The error is generated because the service doesn't exist, which is correct because this is the first install for gitlab-runner.

    WARNING: Since GitLab Runner 10.0 this command is marked as DEPRECATED and will be removed in one of the upcoming releases
    gitlab-runner: Service is not installed.

3. L42-46: check if the gitlab-ci-multi-runner service exists. The warning is generated because of #2710 (closed). The error is generated because the service doesn't exist, which is correct because I already removed gitlab-ci-multi-runner myself.

    WARNING: Since GitLab Runner 10.0 this command is marked as DEPRECATED and will be removed in one of the upcoming releases
    gitlab-ci-multi-runner: Service is not installed.

4. L51-54: install and start gitlab-runner. This generates 2 warnings because of #2710 (closed) again.

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So it seems my output is completely normal. Still, a guide or a bit more descriptive warning/error messages would be nice!

@Xatom Thanks for noticing this. Indeed, we've updated the documentation how to install 10.0 version and how to use old versions if someone needs/wants to, but the documentation about how to update from pre-10.0 to 10.0 was not added.

As for the warning - the post-install script still uses deprecated commands (this is why the message is posted) but in %10.1 we plan to add dedicated service definition files. This will make these commands disappear from the log :).

added Next Patch Release ~60197 labels

We removed deprecation message with 10.0.1.

@axil @tmaczukin Could you help filling that gap?

changed milestone to %10.1

I'll pick it up when I find some free time yes.

assigned to @axil

mentioned in merge request !709

added Documentation and removed ~60197 labels