A backend plugin for Graphite and MegaCarbon to replace the Ceres filesystem store with Apache Cassandra.

1. Download

   • graphite-web
   • carbon_cassandra_plugin
   • this plugin, graphite-cassandra-plugin

2. Extract graphite-web and add the graphite-cassandra-plugin and the carbon-cassandra-plugin to the Graphite lib folder or place them within the PYTHONPATH which will be used by Graphite and MegaCarbon

Modify the db.conf file located at /opt/graphite/conf/carbon-daemons/writer/db.conf

DATABASE_PLUGIN = carbon_cassandra_plugin.CarbonCassandraDatabase

[cassandra]
KEYSPACE = graphite
SERVERS = 192.168.1.1:9160,192.168.1.2:9160,192.168.1.3:9160
REPLICATION_STRATEGY = NetworkTopologyStrategy
STRATEGY_OPTIONS = {"datacenter1" : "1"}
# Nodes created by this daemon will be associated with this DC for
# maintenance tasks such as rollups.
LOCAL_DC_NAME=datacenter1

When running on EC2 with the Ec2Snitch configured, use the following values for the last three options (adjusting the region and replication factor as necessary):

REPLICATION_STRATEGY = NetworkTopologyStrategy
STRATEGY_OPTIONS = {"us-west-2" : "3"}
LOCAL_DC_NAME=us-west-2

The carbon daemon is run from the mounted carbon source, start it with:

sudo -u www-data /vagrant/src/carbon/bin/carbon-daemon.py --config=/opt/graphite/conf/carbon-daemons/writer/ writer start

For more granularity with data rollups (probably just in development) modify management.conf located at /opt/graphite/conf/carbon-daemons/writer/management.conf to make the metric interval more granular:

CARBON_METRIC_INTERVAL = 5

Similarly, change storage-rules.conf in the same directory to add more rollups and/or modify the retention policy:

retentions = 10s:6h, 1m:1d, 15m:1w

Note: the default values for the maximum amount and frequency of writes to the system specified in writer.conf are almost always wrong and will cause you to silently drop data:

MAX_WRITES_PER_SECOND = 100000
MAX_CREATES_PER_MINUTE = inf

Modify local_settings.py file located at /opt/graphite/webapp/graphite/local_settings.py

#####################################
# Cassandra Plugin Settings         #
#####################################
CASSANDRA_KEYSPACE = 'graphite'
CASSANDRA_SERVERS = ['192.168.1.1:9160','192.168.1.2:9160','192.168.1.3:9160']
CASSANDRA_USERNAME = 'cassandra'
CASSANDRA_PASSWORD = 'password'
STORAGE_FINDERS = (
    'graphite_cassandra_plugin.graphite_cassandra_plugin.CassandraFinder',
)

Start the web server using the Django dev server with:

sudo -u www-data /opt/graphite/bin/run-graphite-devel-server.py  /opt/graphite/

The Apache Cassandra schema used for the Carbon backend store is auto created when initialized. The table layout definitions are:

• global_nodes
  • Metric hierarchical relationship representation
• dc_$DCNAME_nodes
  • Replicates the global_nodes hierarchy above but only for nodes created by carb daemons running in the $DCNAME cassandra data centre.
• metadata
  • Metric metedata (Time Step, Retentions, Aggregation Method, etc.)
• ts{VALUE}
  • Metrics, {VALUE} is the defined time value from each unique storage schema item

Edit $USER/.cassandra-cli/assumptions.json and add the following data type assumptions

{
  "graphite" : [ {
    "global_nodes" : [ {
      "KEYS" : "utf8"
    } ]
  }, {
    "metadata" : [ {
      "KEYS" : "utf8"
    } ]
  } ]
}

Using the Apache Cassandra CLI to query for information

[15:29:52] root@cassandra-501:/ # cassandra-cli
Column Family assumptions read from /root/.cassandra-cli/assumptions.json
Connected to: "Acquia Cloud Cluster" on 127.0.0.1/9160
Welcome to Cassandra CLI version 1.2.6

Type 'help;' or '?' for help.
Type 'quit;' or 'exit;' to quit.

[default@unknown] use graphite;
Authenticated to keyspace: graphite
[default@graphite] list metadata;
...
[default@graphite] get metadata['stats_counts.statsd.packets_received'];
...

Except as otherwise noted this software is licensed under the Apache License, Version 2.0

Copyright 2014 Acquia, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.