TL;DR Example

--------------------------------------------------------
-- get the name, pid and attached port of all processes 
-- which are listening on localhost interfaces
--------------------------------------------------------
SELECT DISTINCT 
    process.name, 
    listening.port, 
    process.pid
FROM processes AS process
JOIN listening_ports AS listening
ON process.pid = listening.pid
WHERE listening.address = '127.0.0.1';

   name   | port | pid  
----------+------+------
 postgres | 5432 | 6932
(1 row)

About

So I saw Facebook's OSQuery[1], and thought "That looks awesome, but complicated to build on top of SQLite. Postgres' Foreign Data Wrappers seem like a much better foundation. How long would it take to write the same app on top of Postgres?". Turns out it takes about 15 minutes, for someone who's never written an FDW before :-)

This approach does have the downside that it runs as the postgres user rather than as root, so it can't see the full details of other people's processes, but I'm sure that could be worked around if you really want to.

Currently this is just a proof-of-concept to see how useful Postgres' foreign data wrappers are, and how easy they are to create with the Multicorn python library. Seems the answers are "very useful" and "very easy". If people want to make this more useful by adding more virtual tables, pull requests are welcome~

[1] https://github.com/facebook/osquery

Installation

Let your system python install know about this module:

sudo python setup.py develop

"setup.py develop" will link the current directory so you can modify it; "setup.py install" will copy a snapshot of current code to the OS folder.

Note that either way, you need to restart the postgres server to pick up python code changes.

Create a database with multicorn loaded (See http://multicorn.org/#installation for multicorn installation)

CREATE DATABASE pgosquery;
\c pgosquery;

CREATE EXTENSION multicorn;

Create a FDW table for PgOSQuery:

CREATE SERVER pgosquery_srv foreign data wrapper multicorn options (
    wrapper 'pgosquery.PgOSQuery'
);

CREATE FOREIGN TABLE processes (
    pid integer,
    name character varying,
	username character varying
) server pgosquery_srv options (
    tabletype 'processes'
);  

CREATE FOREIGN TABLE listening_ports (
    pid integer,
    address character varying,
	port integer
) server pgosquery_srv options (
    tabletype 'listening_ports'
);  

Select data:

--------------------------------------------------------
-- get the name, pid and attached port of all processes 
-- which are listening on all interfaces
--------------------------------------------------------
SELECT DISTINCT 
    process.name, 
    listening.port, 
    process.pid
FROM processes AS process
JOIN listening_ports AS listening
ON process.pid = listening.pid
WHERE listening.address = '127.0.0.1';

   name   | port | pid  
----------+------+------
 postgres | 5432 | 6932
(1 row)

Table Types

processes:

Columns are based on psutil's Process attributes, see http://pythonhosted.org/psutil/#psutil.Process

listening_ports:

columns: pid, address, port