[Nix-dev] How to use MySQL

[Linus Arver]

Hello all,

I want to install and use MySQL on NixOS, but am not sure how to
proceed. I've managed to do

    nix-env -iA nixos.mysql55

but trying to get it to run is difficult. Here is what I tried:

    [月 03 0:50:47] - l_k0 ~/prog/sqfmm/mysql
     > mysql
    ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/run/mysqld/mysqld.sock' (2)
    [月 03 0:50:53] 1 - l_k0 ~/prog/sqfmm/mysql
     > systemctl start mysqld
    ==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
    Authentication is required to start 'mysqld.service'.
    Multiple identities can be used for authentication:
     1.  System administrator (root)
     2.  Linus Arver (l)
    Choose identity to authenticate as (1-2): 2
    Password: 
    ==== AUTHENTICATION COMPLETE ===
    Failed to start mysqld.service: Unit mysqld.service not found.
    [月 03 0:52:33] 5 - l_k0 ~/prog/sqfmm/mysql
     > systemctl start mysql 
    ==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
    Authentication is required to start 'mysql.service'.
    Multiple identities can be used for authentication:
     1.  System administrator (root)
     2.  Linus Arver (l)
    Choose identity to authenticate as (1-2): 2
    Password: 
    ==== AUTHENTICATION COMPLETE ===
    Failed to start mysql.service: Unit mysql.service not found.
    [月 03 0:52:57] 5 - l_k0 ~/prog/sqfmm/mysql
     > mysqld
    161003  0:53:16 [Note] mysqld (mysqld 5.5.50) starting as process 12363 ...
    161003  0:53:16 [Warning] Can't create test file /var/lib/mysql/k0.lower-test
    161003  0:53:16 [Warning] Can't create test file /var/lib/mysql/k0.lower-test
    mysqld: Can't change dir to '/var/lib/mysql/' (Errcode: 2)
    161003  0:53:16 [ERROR] Aborting

    161003  0:53:16 [Note] mysqld: Shutdown complete

    [月 03 0:53:16] 1 - l_k0 ~/prog/sqfmm/mysql
     > mysqld_safe
    161003 00:54:16 mysqld_safe Logging to '/var/lib/mysql/k0.err'.
    touch: cannot touch '/var/lib/mysql/k0.err': No such file or directory
    chmod: cannot access '/var/lib/mysql/k0.err': No such file or directory
    mkdir: cannot create directory ‘/run/mysqld’: Permission denied
    chown: invalid user: ‘mysql’
    chmod: cannot access '/run/mysqld': No such file or directory
    161003 00:54:16 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
    /home/l/.nix-profile/bin/mysqld_safe: line 128: /var/lib/mysql/k0.err: No such file or directory
    /home/l/.nix-profile/bin/mysqld_safe: line 165: /var/lib/mysql/k0.err: No such file or directory
    touch: cannot touch '/var/lib/mysql/k0.err': No such file or directory
    chown: invalid user: ‘mysql’
    chmod: cannot access '/var/lib/mysql/k0.err': No such file or directory
    161003 00:54:16 mysqld_safe mysqld from pid file /var/lib/mysql/k0.pid ended
    /home/l/.nix-profile/bin/mysqld_safe: line 128: /var/lib/mysql/k0.err: No such file or directory

The attempt to run *mysqld_safe* was taken from the official docs at
http://dev.mysql.com/doc/refman/5.6/en/starting-server.html.

I see that there are several configuration options for MySQL
(services.mysql.*) defined in the NixOS manual
(https://nixos.org/nixos/manual/options.html#opt-services.mysql.enable)
but this seems to be for enabling it as a service that starts
unconditionally on every boot (configuration.nix), which I want to avoid.

How do I start MySQL without touching configuration.nix? If
configuration.nix is the only sane/preferred way to use MySQL on NixOS,
then is there a resource/wiki/blogpost that discusses a minimal example?
I don't mind trial-and-error with editing my system configs but seeing a
second-hand account of the entire process would be very helpful.

Please forgive me if I have missed any obvious documentation.

Best,
Linus