services: postgresql-role: Add support for password files.

This commit adds a password-file to the postgresql-role field.  It
allows users to provision Postgres roles with a set password.

* gnu/services/databases.scm (postgresql-role): Add password-file field.
(postgresql-role-configuration): Add requirement field.
(postgresql-create-roles): Add support for setting passwords from a
file without leaking passwords to the command line.
(postgresql-role-shepherd-service): Add support for customizable
requirements.
(postgresql-role-service-type): Pass on postgresql-role-configuration
fields values by default, this way user configured fields are not lost.
* gnu/tests/databases.scm: Test it.
* doc/guix.texi: Document the new field and fix the extension point example.

Change-Id: I3aabaa10b0c5e826c5aa874e5649e25a3508a585
Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>

0 files changed, 0 insertions, 0 deletions