This application pushes Exometer metrics to a Graphite server. Also, the application allows selection of relevant Exometer metrics that are created already or will be created in future.

Before sending, metrics are stored in configurable time interval buffer and sent to Carbon (Graphite backend) using Pickle protocol.

This application configured in sys.config file.

Configuration items:

• host - address of a Graphite server. Default is "localhost"
• port - port of Carbon receiving Pickle protocol messages. Default is 2004.
• send_delay - time interval buffer of storing metrics before sending to Graphite. Default is 10 seconds.
• connect_timeout - connection to Carbon timeout. In case connection cannot be established, this application retries specified number of times. After unsuccessful retries single send_delay interval loop is finished with pending messages for the next loop. Default is 5 seconds.
• retries - how many times to try sending messages to Graphite in single send_delay interval loop. number of retries when sending messages to Carbon on the same socket. Default is 2.
• resub_delay - time interval of renewing subscriptions. New metrics can be created or deleted. Default is 60 seconds.
• path_prefix - adds prefix for metrics that are sent to graphite. To automatically get node@host, use atom '$node' which provides erlang:node/0
• force_sname - forces the use of short names when passing $node as the prefix eg. [email protected] would be converted to node@host
• period_replacement - What character to use to replace periods in the graphite path when using $node. defaults to '~'.
• subscriptions - selection of metrics that are wanted to be seen in Graphite. Read next section for detail information.

Selecting metrics is done using Erlang specification matching.

Note that subscription entries are scanned in order, and first match wins. In case an application creates new metrics in runtime, subscriptions are renewed every resubscription_delay,

Top-level generic expresion of a subscription configuration:

{subscriptions, [
    subscription(),
    ...
]}

subscription() = {
                     [
                         {name_pattern(), type()},
                         ...
                     ],
                     datapoint_setting(),
                     interval()
                 }

name_pattern() = [name_part()]

Atom '_' is expression for any.

type() = '_' | counter | fast_counter | gauge | histogram | spiral | duration | meter

Atom '_' is expression for any.

name_part() = '_' | atom() | integer()

    {exometer_graphite, [
        {host, "localhost"},
        {port, 2004},
        {connect_timeout, 5000},
        {send_delay, 3000},
        {retries, 2},
        {resub_delay, 60000},
        {path_prefix, [server1, '$node']},
        {subscriptions, [
            {
                [
                    {[program1,   lager, '_'], '_'},
                    {[program2, lager, '_'], '_'}
                ],
                [mean, max, min],
                20000
            },
            {
                [{[program2, store, '_'], histogram}],
                all,
                10000},
            {
                [{[program3, lager, '_'], '_'}],
                [mean, min, max],
                4000
            },
            {
                [{[program4 | '_'], '_'}],
                all,
                5000
            }
        ]}
    ]},
    {exometer_core, [
        {report, [
            {reporters, [
                {exometer_graphite_reporter, []}
            ]}
        ]}
    ]}

Following name_pattern() will select all available metrics with name starting with program1:

    [program1 | '_']

To check if metrics are sent to Graphite server, in test/sys.config set {port, 2004} instead of {port, 8096} and run make itest. Test will fail. Metrics testA.cpuUsage.value and testB.memUsage.min should appear in Graphite.

To remove these metrics run following command:

sudo rm -r /var/lib/graphite/whisper/server1/