Carbon is one of the components of Graphite, and is responsible for receiving metrics over the network and writing them down to disk using a storage backend. Currently Whisper is our stable, supported backend and Ceres is the work-in-progress future replacement for Whisper.
Client applications can connect to the running carbon-cache.py daemon on port 2003 (default) and send it lines of text of the following format:
my.metric.name value unix_timestamp
performance.servers.www01.cpuUsage 42.5 1208815315
The metric name is like a filesystem path that uses a dot as a separator instead of a forward-slash.
The value is some scalar integer or floating point value
The unix_timestamp is unix epoch time, as an integer.
Each line like this corresponds to one data point for one metric.
Alternatively, they can send pickle-formatted messages to port 2004 (default) which is considered faster than the line-based format.
Once you've got some clients sending data to carbon-cache, you can view graphs of that data through the frontend Graphite Web application.
First you must tell carbon-cache what user it should run as. This must be a
user with write privileges to
$GRAPHITE_ROOT/storage/whisper. Specify the
user account in
$GRAPHITE_ROOT/conf/carbon.conf. This user must also have
write privileges to
Alternatively, you can run
Twistd plugins, for example:
Usage: twistd [options] carbon-cache [options] Options: --debug Run in debug mode. -c, --config= Use the given config file. --instance= Manage a specific carbon instance. [default: a] --logdir= Write logs to the given directory. --whitelist= List of metric patterns to allow. --blacklist= List of metric patterns to disallow. --version Display Twisted version and exit. --help Display this help and exit.
Common options to
--prefix are fully supported and have precedence over
carbon-*'s own options. Please refer to
twistd --help for the full list of
Writing a client
First you obviously need to decide what data it is you want to graph with
graphite. The script examples/example-client.py demonstrates a simple client
loadavg data for your local machine to carbon on a minutely basis.
The default storage schema stores data in one-minute intervals for 2 hours. This is probably not what you want so you should create a custom storage schema according to the docs on the Graphite wiki.