This overhauls the Datadog module a bit to be much more useful. In
particular, it adds support for nginx and postgresql monitoring
integrations to dd-agent. These have to exist in separate files under
/etc/dd-agent, so the module just exposes then as separate options. In
the future, more integrations could be added this way.
In the process of doing this, I also had to rename the dd-agent user to
datadog. Note the UIDs did not change, so this is strictly backwards
compatible. The reason for this is to make it easier to create a
'datadog' postgres user with access to pg_stats, as 'dd-agent' typically
isn't a valid username. This allows the out of the box configurations to
be used.
Signed-off-by: Austin Seipp <aseipp@pobox.com>
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.
