Description of problem:
The collectd-postgresql plugin cannot connect to a locally-running PostgreSQL instance via UNIX socket because of this AVC denial:

type=AVC msg=audit(1465396307.731:4222): avc:  denied  { write } for  pid=20104 comm="collectd" name=".s.PGSQL.5432" dev="tmpfs" ino=36537 scontext=system_u:system_r:collectd_t:s0 tcontext=system_u:object_r:postgresql_var_run_t:s0 tclass=sock_file

Version-Release number of selected component (if applicable):
collectd-5.5.1-3.el7.x86_64
collectd-postgresql-5.5.1-3.el7.x86_64
selinux-policy-3.13.1-60.el7_2.3.noarch
selinux-policy-targeted-3.13.1-60.el7_2.3.noarch

How reproducible:
Always

Steps to Reproduce:
1. Install collectd and collectd-postgresql (from EPEL)
2. Add <Plugin postgresql> and <Database {name}>  entries to collectd.conf, using a filesystem directory for Host, e.g.

LoadPlugin postgresql
<Plugin postgresql>
    <Database postgres>
        Host "/run/postgresql"
        User postgres
    </Database>
</Plugin>
3. Start collectd and observe an error like this in syslog

Jun  8 14:31:47 fmosng-56d3ff collectd[20094]: Failed to connect to database postgres (postgres): could not connect to server: Permission denied#012#011Is the server running locally and accepting#012#011connections on Unix domain socket "/run/postgresql/.s.PGSQL.5432"?


Actual results:
collectd is unable to connect to the database instance

Expected results:
collectd should be able to connect to the database instance


Additional info:
The following policy modification resolves the issue:

policy_module(collectdlocal, 1.0.0)

gen_require(`
	type collectd_t;
')

optional_policy(`
	postgresql_stream_connect(collectd_t)
')