Closes#76812. Closes#77126.
OsProbe was only capable of handle cgroup data in the v1 format.
However, Debian 11 uses cgroups v2 by default, and Elasticsearch isn't
capable of reporting any cgroup information. Therefore, add support for
the v2 layout.
Note that we have to open access to all of /sys/fs/cgroup because with
cgroups v2, the files we need are in an unpredictably location.
The changelog generation process currently relies on version
information being present in the changelog YAML descriptors. However,
this makes them difficult to update in some scenarios. For example,
if a PR is merged and subsequently labelled for backporting, our
automation won't update the versions in the changelog YAML.
We can make the process more flexible by removing version data from
the changelog YAML files, and instead inferring the versions from
each changelog YAML file's existence in the git tree at each tag
in the minor series.
This change makes the process more ergonomic for developers, but
harder to test, since I can't simply concoct YAML data for a range
of versions. Instead, I've added a number of unit tests, and tried
to exercise all the relevant parts.
It is now an error to include `versions` the YAML file.
Closes#76148. Previously, in #74327, we added support for setting
Elasticsearch settings in the Docker image via environment variables.
However there are scenarios e.g in Kubernetes where it is easy to
accidentally define environment variables that the ES startup process
rejects.
Work around this by using the more explicit env var prefix
`ES_SETTING_`.
Explicitly set permissions for all files in the Elasticsearch home
directory to the minimum required set, and change ownership to
`root:root` where possible.
Rory Hunter
Mark Vieira