[debian-mysql] Bug#663720: mysql-server: problems upgrading packages that only suggest/recommand a database server

[Andreas Beckmann]

Package: mysql-server
Severity: normal
User: debian-qa at lists.debian.org
Usertags: piuparts


Hi,

this is probably not a bug in mysql-server, but the MySQL maintainers
might know the best solution for this problem.

I'm currently experimenting with piuparts (i.e. allowing to run a local
database server in the chroot) and do squeeze->wheezy upgrade tests.
During these experiments I discovered the following upgrade failure, I
give only a rough outline what happend, the full log is attached:

* setup minimal squeeze chroot (do not install recommends by default)
* apt-get install mysql-server  # there is only a Suggests: mysql-server
* apt-get install pdns-backend-mysql
* switch sources.list from squeeze to wheezy
* apt-get dist-upgrade
  - replaces/unpacks mysql-server*
  - repalces/unpacks pdns-server*
  - configures pdns-server* (fails because database is not running)
  - configures mysql-server*

Log excerpts from the dist-upgrade part:

  [...]
  Preparing to replace mysql-server-5.1 5.1.49-3 (using .../mysql-server-5.1_5.1.61-2_amd64.deb) ...
  Stopping MySQL database server: mysqld.
  Stopping MySQL database server: mysqld.
  Unpacking replacement mysql-server-5.1 ...
  Preparing to replace mysql-server-core-5.1 5.1.49-3 (using .../mysql-server-core-5.1_5.1.61-2_amd64.deb) ...
  Unpacking replacement mysql-server-core-5.1 ...
  [...]
  Preparing to replace pdns-server 2.9.22-8+squeeze1 (using .../pdns-server_3.0-1.1_amd64.deb) ...
  Unpacking replacement pdns-server ...
  Preparing to replace pdns-backend-mysql 2.9.22-8+squeeze1 (using .../pdns-backend-mysql_3.0-1.1_amd64.deb) ...
  Unpacking replacement pdns-backend-mysql ...
  [...]
  Setting up pdns-server (3.0-1.1) ...
  Installing new version of config file /etc/init.d/pdns ...
  Setting up pdns-backend-mysql (3.0-1.1) ...
  dbconfig-common: writing config to /etc/dbconfig-common/pdns-backend-mysql.conf
  
  Creating config file /etc/dbconfig-common/pdns-backend-mysql.conf with new version
  
  Creating config file /etc/powerdns/pdns.d/pdns.local.gmysql with new version
  detected upgrade from previous non-dbconfig version.
  creating database backup in /var/cache/dbconfig-common/backups/pdns-backend-mysql_2.9.22-8+squeeze1.mysql.
  ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2).
  unable to connect to mysql server.
  error encountered backing up the old database:
  ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)
  dbconfig-common: pdns-backend-mysql configure: aborted.
  dbconfig-common: flushing administrative password
  dpkg: error processing pdns-backend-mysql (--configure):
   subprocess installed post-installation script returned error exit status 1
  [...]
  Setting up mysql-client-5.1 (5.1.61-2) ...
  Setting up mysql-server-5.1 (5.1.61-2) ...
  Installing new version of config file /etc/mysql/debian-start ...
  Stopping MySQL database server: mysqld.
  Starting MySQL database server: mysqld.
  Checking for tables which need an upgrade, are corrupt or were 
  not closed cleanly..
  Setting up mysql-server (5.1.61-2) ...
  [...]

Having a package that needs a database only Suggests/Recommends the
corresponding database server is good since it allows to use a remote
database server without being forced to install a local one. I did not
try whether this problem also happens if the package Recommends instead
of Suggests mysql-server. The problem is not frequent as it highly
depends on the set of packages being installed and the upgrade and
configuration order choosen by apt/dpkg.

dpkg --configure --pending would probably fix all the unconfigured
packages.  But as long as a package is working in its default
configuration, there should be an error-free upgrade path to the next
distribution.

What is the recommended way of packaging a database-using application
that avoids this pitfall?

I was googling around a bit but found nothing more than
http://people.debian.org/~seanius/policy/dbapp-policy.html/
and the dbconfig-common documentation.


Andreas
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