When starting from a clean slate, the couchdb service fails.
First, the pre-start script fails because it tries to chown the uriFile,
which doesn't exist. It also doesn't ensure that the directory in which
the uriFIle is placed is writeable by couchdb, which could also cause
failure (though I didn't observe this).
Additionally, the log file's default location isn't a directory owned by
couchdb, nor is the file guaranteed to exist, nor is it guaranteed to be
chowned to the appropriate user. All of which can cause unexpected
failure.
As a bonus I made a small change in the description of the configFile
attribute, in the hopes of making it a little more obvious why it
existed.
Commit 89fee1006c ("nixos/redis: clean up
option types") broke nixos evaluation:
error: attempt to call something which is not a function but a set, at .../nixpkgs/nixos/modules/services/databases/redis.nix:111:28
Fix it.
Reported by Oliver Charles (thanks!).
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
The postgresql module has a postStart section that waits for a database
to accept connections before continuing. However, this assumes various
properties about the database - specifically the database user
and (implicitly) the database name. This means that for old
installations, this command fails because there is no 'postgres' user,
and the service never starts.
While 7deff39 does create the 'postgres' user, a better solution is to
use `pg_isready`, who's sole purpose is to check if the database is
accepting connections. This has no dependency on users, so should be
more robust.
Old PostgreSQL installations were created using the 'root' database
user. In this case, we need to create a new 'postgres' account, as we
now assume that this is the superuser account.
Unfortunately, these machines will be left with a 'root' user as
well (which will have ownership of some databases). While PostgreSQL
does let you rename superuser accounts, you can only do that when you
are connected as a *different* database user. Thus we'd have to create a
special superuser account to do the renaming. As we default to using
ident authentication, we would have to create a system level user to do
this. This all feels rather complex, so I'm currently opting to keep the
'root' user on these old machines.
as per postgresql manual, interactions with psql should be carried
out with the postgresql system user and postgresql db user by default.
ensure it happens in postStart.
According to the MySQL manual, this is a perfectly legal way of
shutting down the server. The shutdown logs also looks fine:
systemd[1]: Stopping MySQL Server...
mysqld[5114]: 140319 8:36:12 [Note] /nix/store/sc26mz82k97mbpx3d1abzn3rrbd155ws-mariadb-10.0.8/bin/mysqld: Normal shutdown
mysqld[5114]: 140319 8:36:12 [Note] Event Scheduler: Purging the queue. 0 events
mysqld[5114]: 140319 8:36:12 [Note] InnoDB: FTS optimize thread exiting.
mysqld[5114]: 140319 8:36:12 [Note] InnoDB: Starting shutdown...
mysqld[5114]: 140319 8:36:14 [Note] InnoDB: Shutdown completed; log sequence number 1619078
mysqld[5114]: 140319 8:36:14 [Note] /nix/store/sc26mz82k97mbpx3d1abzn3rrbd155ws-mariadb-10.0.8/bin/mysqld: Shutdown complete
systemd[1]: Stopped MySQL Server.
