TelemetryMetricsMnesia

Telemetry.Metrics reporter and metrics backend based on Mnesia DB.

Features

Full compatibility with Telemetry.Metrics specification.
Supports distribution between BEAM nodes.
In-memory and persistant data storage modes.
Custom metric aggregaaion support.
Has no external dependences.

Installation

Just add the reporter to your dependencies in mix.exs:

defp deps do
  [
    {:telemetry_metrics_mnesia, "~> 0.1.0"}
  ]
end

Usage

To use it, start the reporter with the start_link/1 function, providing it a list of Telemetry.Metrics metric definitions:

import Telemetry.Metrics

TelemetryMetricsMnesia.start_link(
  metrics: [
    counter("http.request.count"),
    sum("http.request.payload_size"),
    last_value("vm.memory.total")
  ]
)

or put it under a supervisor:

import Telemetry.Metrics

children = [
  {TelemetryMetricsMnesia, [
    metrics: [
      counter("http.request.count"),
      sum("http.request.payload_size"),
      last_value("vm.memory.total")
    ]
  ]}
]

Supervisor.start_link(children, ...)

By default the reporter uses in-memory storage without distribution.

Getting metrics values

There is a unified API for retrieving metrics data. Use TelemetryMetricsMnesia.fetch(metric_name, opts) to do it:

alias TelemetryMetricsMnesia, as: Metrics

# Simple metrics
%{"Counter" => request_count} = Metrics.fetch([:http, :request, :count])
%{"Counter" => request_count_per_minute} = Metrics.fetch([:http, :request, :count], granularity: :minite)

%{"Sum" => total_requests_size} = Metrics.fetch([:http, :request, :payload_size])
%{"Sum" => request_size_per_second} = Metrics.fetch([:http, :request, :count], granularity: :second)


%{"LastValue" => total_memory} = Metrics.fetch([:vm, :memory, :total])

# Complex metrics

%{
    "Distribution" => %{
        median: median,
        p75: p7_5,
        p90: p9_0,
        p95: p9_5,
        p99: p99
    }
} = TelemetryMetricsMnesia.fetch([:http, :request, :duration])

%{
    "Summary" => %{
        mean: avg,
        variance: var,
        standard_deviation: sd,
        median: median,
        count: count
    }
} = TelemetryMetricsMnesia.fetch([:http, :request, :duration])

# Multiple metrics with the same name

%{
    "Distribution" => %{
        median: median,
        p75: p7_5,
        p90: p9_0,
        p95: p9_5,
        p99: p99
    },
    "Summary" => %{
        mean: avg,
        variance: var,
        standard_deviation: sd,
        median: median,
        count: count
    }
} = TelemetryMetricsMnesia.fetch([:http, :request, :duration])

# Metric with tags
# Strated as `counter("http.request.count", tags: [:endpoint, :code])`

%{
    "Counter" => %{
        %{endpoint: "/", code: 200} => app_requests_success,
        %{endpoint: "/", code: 500} => app_requests_server_fail,
        %{endpoint: "/api", code: 200} => api_requests_success
    }
} = TelemetryMetricsMnesia.fetch([:http, :request, :counter])

Copyright and License

TelemetryMetricsMnesia source code is released under MIT license.

See LICENSE for more information.