[debian-mysql] Bug#1028273: MariaDB systemd: make multiple systemd files compatible with --build=all

[Otto Kekäläinen]

Package: mariadb-server
Severity: wishlist
Tags: newcomer

Upstream MariaDB ships with multiple systemd service files but we
don't have it enabled in MariaDB packaging in Debian[1].

This issue is tagged newcomer friendly as it only requires a minimal
knowledge[2] of existing MariaDB packaging in Debian.

We need help from somebody who can deep dive into both systemd to
understand how this feature is supposed to work correctly, and to read
up on what the Debian Policy says about systemd usage and what the
conventions are for this specifically in Debian.

The section in debian/rules currently looks like this, explaining the problem:

# Install mariadb.socket without enabling it, keep using
mariadb.service by default
# @TODO: Temporarily disable extra and socket systemd file installation until
# a '--build=all' compatible mechanism is found
override_dh_systemd_enable:
dh_systemd_enable --name=mariadb
dh_systemd_enable --no-enable --name=mariadb@ # mariadb at .service
# dh_systemd_enable --no-enable --name=mariadb mariadb.socket
# dh_systemd_enable --no-enable --name=mariadb-extra mariadb-extra.socket
# dh_systemd_enable --no-enable --name=mariadb@ mariadb.socket
# dh_systemd_enable --no-enable --name=mariadb-extra@ mariadb-extra.socket


If these lines are enabled, the build fails with error:

    dh_systemd_enable: warning: Requested unit "mariadb.socket" but it was
    not found in any package acted on.

See example of failing CI job at
https://salsa.debian.org/mariadb-team/mariadb-server/-/jobs/3763077



[1] https://salsa.debian.org/mariadb-team/mariadb-server
[2] https://salsa.debian.org/mariadb-team/mariadb-server/-/wikis/Contributing-to-MariaDB-packaging-in-Debian