services: postgresql: Add log directory support.

* gnu/services/databases.scm (postgresql-configuration-log-directory): New
procedure.
(<postgresql-configuration>)[log-directory]: New field.
(postgresql-activation): Create the log directory.
(postgresql-shepherd-service): Honor it.
* gnu/tests/databases.scm (%postgresql-log-directory): New variable.
(log-file): New test case.
* doc/guix.texi (Database Services): Document it.

1 files changed, 5 insertions, 0 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index b01bbf0d96..f4fbe6b0e6 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -19344,6 +19344,11 @@ The configuration file to use when running PostgreSQL@.  The default
 behaviour uses the postgresql-config-file record with the default values
 for the fields.
 
+@item @code{log-directory} (default: @code{"/var/log/postgresql"})
+The directory where @command{pg_ctl} output will be written in a file
+named @code{"pg_ctl.log"}.  This file can be useful to debug PostgreSQL
+configuration errors for instance.
+
 @item @code{data-directory} (default: @code{"/var/lib/postgresql/data"})
 Directory in which to store the data.