Running the Relay
java -jar graphite-relay-0.1.jar -c /path/to/relay.properites
A backend strategy will pick which Graphite backends to send a given metric to. The include ones are:
Broadcast- Broadcast each metric to all backends
ConsistentHash- Use a simple consistent hash to send an update to a backend with a minimal change in (metric -> backend) mapping on backend addition or deletion.
RoundRobin- Cycle through the backends sending a batch of metrics to one at a time (Not reccomended as this will not play nicely with other Graphite Tools).
When a backend goes down, this relay will buffer up messages to a point. After
that point, it will dump updates to an
OverflowHandler to ensure we don't blow
the heap. The
OverflowHandler should do something with an update toher than
keep it in memory. The included implementations are:
BitchingOverflowHandler- Simply log ever so often to let someone know that not all metrics are making it to backends.
LoggingOverflowHandler- Stream the metrics to a rolling, gzipped set of files on disk which can be replayed with netcat (or similar) at a later point.
There are a number of variables you can set in the config file. Popular ones are set below. If a required parameter is missing it will manifest itself (for the moment) with Guice vomiting a stack trace on you while trying to start the program.
Graphite backends which will recieve messages in the normal Graphite Pickle
format. This should be a line-delimited list of
host:port pairs. For example:
relay.backends: \ localhost:1234 \ localhost:1235 \ localhost:1236 \ localhost:1237
Number of updates to buffer for each host in the event that it goes down
Default port to listen on. This port will expect line-oriented Graphite update metrics.
Number of seconds to sleep before trying to reconnect to a disconnected backend.
Backend Strategy to use for finding a backend for each metric. Default available values are:
graphite.relay.backend.strategy.RoundRobinYou may also set to the FQCN of any other
CLASSPATH. If using the
ConsistentHashstrategy, you will also have to set
hash.replicasin the config. A reasonable default value is
Handler which will recieve updates that no backend is available to handle. This is generally because it is unavailable or overwhelmed. Default available values are:
relay.backendstrategy, the FQCN of any other
CLASSPATHis just as valid. If using the
LoggingOverflowHandler, you must set
overflow.directoryin the configuration to a directory that the current user has permission to create.
A complete config file might be as follows:
relay.hostbuffer: 1000 relay.port: 2002 relay.reconnect: 2 relay.backendstrategy: graphite.relay.backend.strategy.ConsistentHash hash.replicas: 20 relay.overflowhandler: graphite.relay.overflow.LoggingOverflowHandler overflow.directory: /mnt/overflow/ relay.backends: \ localhost:1234 \ localhost:1235 \ localhost:1236 \ localhost:1237
The included Pickle formatting is very rudimentary and only groks the data type that the Graphite backends expect. Because of its simple format, this will actually use a very early Pickle encoding, which cPickle and friends can grok, but may not be most effecient.