[debian-mysql] Bug#1071699: mariadb-server: Moved mariadb socket, debian-start reports error connecting to old socket

[Eric Towers]

Package: mariadb-server
Version: 1:10.11.6-0+deb12u1
Severity: normal
X-Debbugs-Cc: fuzzyeric at gmail.com

Dear Maintainer,

First, thanks for your hard work maintaining the MariaDB (server)
package.  You're awesome.


After moving /var/lib/mysql/ to /mnt/tera/mariadb/ ,
modifying /etc/mysql/mariadb.conf.d/50-server.conf
    from: datadir = /var/lib/mysql
    to:   datadir = /mnt/tera/mariadb ,
modifying /etc/mariadb.cnf
    uncomment: port = 3306
    from:      socket = /run/mysqld/mysqld.sock
    to:        socket = /mnt/tera/mariadb/mysqld.sock ,
and modifying /etc/mariadb.conf.d/50-client.cnf
    add to [client] section:
        port = 3306
	socket = /mnt/tera/mariadb/mysqld.conf ,
starting mariadb (as root)
    systemctl start mariadb
yields a successfully running mariadb
    tested by: mysqladmin -u root status
    returns: Uptime: 1644  Threads: 1  Questions: 4  Slow queries: 0  Opens: 17  Open tables: 10  Queries per second avg: 0.002
but debian start returns an error (there may be a smarter way to extract
the debian-start messages, but I know this one works)
    journalctl -b | grep debian-start
    returns for this start: 
        [...] /etc/mysql/debian-start[141397]: Upgrading MySQL tables if necessary.
        [...] /etc/mysql/debian-start[141408]: Checking for insecure root accounts.
        [...] debian-start[141411]: ERROR 2002 (HY000): Can't connect to local server through socket '/run/mysqld/mysqld.sock' (2)
Checking /etc/mysql/debian-start and
/usr/share/mysql/debian-start.inc.sh, I don't see a hardcoded socket
path, so I don't know where this socket path is coming from.

I did not expect an error from debian-start.  I expect that debian-start
indicates if it is attaching to the server via the socket or via 
localhost/127.0.0.1 (and the port).  In fact, if both are configured, I
imagine it would check reachability through both mechanisms and report
results for both.  I also expect it will use the configured mechanisms,
not defaults.

Correct(?) solution: debian-start uses the configured mechanisms to probe
the mariadb server and reports success/fail of each.  Errors are only
generated if the configured access mechanisms fail.

Passable workaround: systemd's maraidb startup script creates a link 
from /run/mysqld/mysqld.sock to wherever that socket actually is when 
it starts up.

My hack-ish workaround: I have linked the wrong location to the configured 
location.
    ln -s /mnt/tera/mariadb/mysqld.sock /run/mysqld/mysqld.sock
    chown -h mysql:mysql /run/mysqld/mysqld.sock
I don't have a clear understanding of the lifetime of the /run/*
(sub-)filesystem, so I don't know how long this hack will prevent the
error message.

Again, thanks for your hard work!

-- System Information:
Debian Release: 12.5
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 6.1.0-21-amd64 (SMP w/6 CPU threads; PREEMPT)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages mariadb-server depends on:
ii  adduser                3.134
ii  debconf [debconf-2.0]  1.5.82
ii  galera-4               26.4.13-1
ii  gawk                   1:5.2.1-2
ii  iproute2               6.1.0-3
ii  libc6                  2.36-9+deb12u7
ii  libdbi-perl            1.643-4
ii  libpam0g               1.5.2-6+deb12u1
ii  libssl3                3.0.11-1~deb12u2
ii  libstdc++6             12.2.0-14
ii  lsof                   4.95.0-1
ii  mariadb-client         1:10.11.6-0+deb12u1
ii  mariadb-common         1:10.11.6-0+deb12u1
ii  mariadb-server-core    1:10.11.6-0+deb12u1
ii  passwd                 1:4.13+dfsg1-1+b1
ii  perl                   5.36.0-7+deb12u1
ii  procps                 2:4.0.2-3
ii  psmisc                 23.6-1
ii  rsync                  3.2.7-1
ii  socat                  1.7.4.4-2
ii  zlib1g                 1:1.2.13.dfsg-1

Versions of packages mariadb-server recommends:
ii  libhtml-template-perl           2.97-2
ii  mariadb-plugin-provider-bzip2   1:10.11.6-0+deb12u1
ii  mariadb-plugin-provider-lz4     1:10.11.6-0+deb12u1
ii  mariadb-plugin-provider-lzma    1:10.11.6-0+deb12u1
ii  mariadb-plugin-provider-lzo     1:10.11.6-0+deb12u1
ii  mariadb-plugin-provider-snappy  1:10.11.6-0+deb12u1
ii  pv                              1.6.20-1

Versions of packages mariadb-server suggests:
ii  bsd-mailx [mailx]  8.1.2-0.20220412cvs-1
pn  mariadb-test       <none>
pn  netcat-openbsd     <none>

-- Configuration Files:
/etc/mysql/mariadb.conf.d/50-server.cnf changed:
[server]
[mysqld]
pid-file                = /run/mysqld/mysqld.pid
basedir                 = /usr
datadir                 = /mnt/tera/mariadb
bind-address            = 127.0.0.1
expire_logs_days        = 10
character-set-server  = utf8mb4
collation-server      = utf8mb4_general_ci
[embedded]
[mariadb]
[mariadb-10.11]


-- debconf information:
  mariadb-server/old_data_directory_saved:
  mariadb-server/nis_warning:
  mariadb-server/postrm_remove_databases: false