Renaming the Prometheus repositories main branch

[Julien Pivotto]

Dear developers,

In PromCon 2020, the Prometheus-team sent the following message:

In tech, we tend to take the view that politics should be kept out.
This is wrong. Open Source is fundamentally a political movement, a
movement to literally change society, to create equality and freedom.
And not seeing the need to address all these concerns is a position
which is coming from a fundamental misunderstanding of society; and of
privilege
Resist racism
Resist facism
Black lives matter

This was true in 2020, it is still true in 2021, it will stay true in
the future.

GitHub has released the "branch renaming" feature in the last days,
enabling repository owners to rename the branches, redirecting pull
requests, etc.

I'd like that as a project, we rename the "master" branch to "main" for
all the Prometheus and Prometheus-community projects.

This will be more work than just clicking the button on the UI as we
will need an update on the CI. It will also impact people who rebuild
the project downstream.

If there is no objection, I will work on the exact details with the
in-team CI team, and we will announce the plans and dates in this
mailing list.

Read more: https://github.com/github/renaming

--
Julien Pivotto
@roidelapluie

[Julien Pivotto]

Hello,

My plan is to proceed with prometheus/prometheus in the second half of
February. I am basically waiting for the 2.25 release first.

Then, the master branch would be renamed to main.

BEFORE THE CHANGE:

1. An issue will be created in the github repo and "pinned", to better
inform our contributors of the change.
2. Our circle orb will gain a public_main action (additionally of the
publish_master)
3. A pull request will be open to change the .circleci config.


CHANGE:

4. The branch is renamed in the github UI.
5. Netlify config is updated (for UI PR's)
6. Merge request 3. (see above) is merged.

AFTER:

After a few days, we close the pinned issue which was there to inform
contributors of the change.


Regards,

--
Julien Pivotto
@roidelapluie