Exometer InfluxDB reporter

This reporter pushes data to InfluxDB.

Usage

1. Add exometer_influxdb to your list of dependencies in rebar.config:

   {deps, [
       {exometer_influxdb, ".*", {git, "https://github.com/travelping/exometer_influxdb.git", "master"}}
   ]}.

2. Ensure exometer_influxdb is started before your application:

   {applications, [exometer_influxdb]}.

3. Configure it:

   {exometer, 
       {reporters, [
           {exometer_report_influxdb, [{protocol, http}, 
                                       {host, <<"localhost">>},
                                       {port, 8086},
                                       {db, <<"exometer">>},
                                       {tags, [{region, ru}]}]}
       ]}
   }.

Available options:

• host - InfluxDB host. 127.0.0.1 by default.
• protocol - http or udp for operating with InfluxDB. http by default.
• port - InfluxDB port. 8086 by default.
• db - database on InfluxDB for writing data. exometer by default
• username - username for authorization on InfluxDB.
• password - password for authorization on InfluxDB.
• timestamping - enable timestamping, false by default.
• tags - list of default tags for each data point. The host is automatically included here.
• batch_window_size - set window size in ms for batch sending. This means reported will collect measurements within this interval and send all measurements in one packet. 0 by default.

Timestamping is by default done by influxdb itself. To enable timestamping with the reporter you can use true or {true, Precision} where Precision is a unit taken from [n,u,ms,s,m,h]. The default unit is u.

Besides the tags for the reporter initialization it is possible to add other tags via the Extra parameter of exometer_report:subscribe/5 as done here with environment variables:

{exometer, 
    {subscriptions, [
         {exometer_report_influxdb, [erlang, memory], total, 5000, true, [{tag, <<"value">>}]},
    ]}
}.

By default the in influxdb visible name of the metric is derived from the exometer id: here [erlang, memory] is translated to erlang_memory. It is possible to remove an item from this list by naming itself or its position with the from_name keyword. A removed element is then used as tag:

exometer_report:subscribe(exometer_report_influxdb, [erlang, memory], total, 5000, true, [{tag, {from_name, 2}}]).

This will result in a name erlang with the tag pair {tag, memory} (plus the default pair {host, Host}).

TODO

• Tests
• Reconfiguration on runtime