Rolf

'Azamat is run Big Data analytics on famous last words in devops. Most common is "I know, I roll own monitoring tool!"' -- @DEVOPS_BORAT

Overview

Monitoring and graphing tool like Munin or collectd.
Written in Erlang.
Sample frequency down to 1 second, configured per plug-in.
Record data on multiple nodes in parallel.
Asynchronous data gathering.
HTTP interface for HTML, graphs and data via JSON.
Writing plug-ins is simple. Plug-ins are kept resident between updates, as in collectd.
Runs anywhere Erlang runs (at least Linux, OS X, Windows).

Getting started

Configure which node(s) should be recorders in etc/app.config.

[{rolf, [recorders, [rolf@john]]}].

Configure which services should run on which nodes in etc/services.config.

{node, rolf@john, [disk, loadtime]}.
{node, rolf@paul, [disk]}.
{node, rolf@george, [disk]}.
{node, rolf@ringo, [disk]}.

Start Rolf on each machine.

[user@john ~] rolf start
[user@paul ~] rolf start
[user@george ~] rolf start
[user@ringo ~] rolf start

Architecture

An Erlang cluster is created. Each node runs the rolf application.
One node is designated the recorder by it's config file.
If the cluster has no recorder, nothing happens.
If a recorder has been started, service configuration is distributed to all other nodes by the recorder.
A node manager process starts services and they start emitting samples.
Services can be implemented as Erlang functions, external commands or external daemons.
Services collect samples and send them to all live recorders.
Recorders and collectors can be added and removed from the cluster dynamically.

The supervision tree of an Rolf node looks like this (node has recorder):

rolf_sup
├── rolf_recorder
│   └── errd_server
└── rolf_collector_sup
    ├── rolf_service (svc1)
    └── rolf_service (svc2)
        └── rolf_external

Plugins

Plugins add additional collectors to Rolf.

Plugins live in plugins.
A plugin has a config file, see plugins/loadtime/loadtime.config for an example.
Plugin config can be overridden per-site by customising services.config.
Plugins can use an Erlang module, a command or a daemon to collect data.
Plugin collectors written in Erlang should implement the rolf_collector behaviour.
The collect/1 function should capture data. The argument, Service, is a service record, which includes lots of useful info such as name and options (see apps/rolf/include/rolf.hrl for more info).

Author

Ben Godfrey, ben@ben2.com, http://aftnn.org/.

License

Rolf - a monitoring and graphing tool like Munin or collectd.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.