Alternative PostgreSQL plugin for munin — Part 2

Tue 10 November 2015

Filed under sysadmin

First Alpha Releases

I have finished porting all "virtual" graphs from the official plugins. The source of this release can be found on github.

This is currently a very rough cut release. Keep in mind:

There is barely any documentation
The plugin does not support autoconfig
It is likely that some major refactoring will go on once the docs are written.
Maybe things will change. Maybe not.

Trying it out

Installation

Installing the plugin is fairly easy:

Clone the github repository somewhere and switch to the alpha tag:

git clone https://github.com/exhuma/munin-plugins.git /opt/exhuma/munin-plugins
cd /opt/exhuma/munin-plugins
git checkout postgres-multigraph/v1.0.0a2

Install psycopg2:
```
apt-get install python-psycopg2
```

Symlink the plugin into your munin-node:

ln -s /opt/exhuma/munin-plugins/pg_multigraph /etc/munin/plugins/pg_multigraph

Configuration

The plugin reads the following environment variables:

PG_DBNAME (default='template1')

The database name to connect to.

PG_USER (default='postgres')

The username used to connect.

PG_PASSWORD (default='')

The password used to connect. If empty, perform a passwordless login.

PG_HOST (default='')

The DB host. If empty, connect using the unix domain socket.

PG_PORT (default=0)

The port which is used to connect. If 0, connect using the unix domain socket.

PG_MULTIGRAPHS (default='__all__')

A comma-separated list of which graphs to create. At the time of this writing the following names are accepted:

__all__
connections
locks
query_ages
row_access
scantypes
sizes
indexio
sequenceio
tableio

The special name __all__ causes all graphs to be generated.

What's different?

Compared to the plugins bundled with munin, there are a couple of differences in the generated graphs:

Locks show both "granted" and "waiting" locks. The official plugin did not differentiate between both.
postgres_transactions_ has not been ported. I have not use-case for that one.
index scan and sequential scan is removed from tuple access. It is now also related to row access. Both scan fetches are more related to indices and pollute that graph.
Buffer Cache has been removed and replaced by sepearate I/O plugins for Tables, Sequences and Indices.

Screenshots?

I have currently no screenshots at hand which are really representative. All I have is some "work in progress" stuff from my laptop. They don't represent the graphs very well.