Prometheus.io client in Erlang
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README.md

Prometheus.io client for Erlang

Copyright (c) 2016 Ilya Khaprov <i.khaprov@gmail.com>.

Version: 3.1.0

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Prometheus.io monitoring system and time series database client in Erlang.

RabbitMQ Dashboard

  • IRC: #erlang on Freenode;
  • Slack: #prometheus channel - Browser or App(slack://elixir-lang.slack.com/messages/prometheus).

Integrations

Erlang VM & OTP Collectors

Example Console Session

Run shell with compiled and loaded app:


    $ rebar3 shell

Start prometheus app:


prometheus:start().

Register metrics:

prometheus_gauge:new([{name, pool_size}, {help, "MongoDB Connections pool size"}]),
prometheus_counter:new([{name, http_requests_total}, {help, "Http request count"}]).
prometheus_summary:new([{name, orders}, {help, "Track orders count/total sum"}]).
prometheus_histogram:new([{name, http_request_duration_milliseconds},
                               {labels, [method]},
                               {bounds, [100, 300, 500, 750, 1000]},
                               {help, "Http Request execution time"}]).

Use metrics:

prometheus_gauge:set(pool_size, 365),
prometheus_counter:inc(http_requests_total).
prometheus_summary:observe(orders, 10).
prometheus_summary:observe(orders, 15).
prometheus_histogram:observe(http_request_duration_milliseconds, [get], 95).
prometheus_histogram:observe(http_request_duration_milliseconds, [get], 100).
prometheus_histogram:observe(http_request_duration_milliseconds, [get], 102).
prometheus_histogram:observe(http_request_duration_milliseconds, [get], 150).
prometheus_histogram:observe(http_request_duration_milliseconds, [get], 250).
prometheus_histogram:observe(http_request_duration_milliseconds, [get], 75).
prometheus_histogram:observe(http_request_duration_milliseconds, [get], 350).
prometheus_histogram:observe(http_request_duration_milliseconds, [get], 550).
prometheus_histogram:observe(http_request_duration_milliseconds, [get], 950).
prometheus_histogram:observe(http_request_duration_milliseconds, [post], 500),
prometheus_histogram:observe(http_request_duration_milliseconds, [post], 150).
prometheus_histogram:observe(http_request_duration_milliseconds, [post], 450).
prometheus_histogram:observe(http_request_duration_milliseconds, [post], 850).
prometheus_histogram:observe(http_request_duration_milliseconds, [post], 750).
prometheus_histogram:observe(http_request_duration_milliseconds, [post], 1650).

Export metrics as text:

io:format(prometheus_text_format:format()).

->

# TYPE http_requests_total counter
# HELP http_requests_total Http request count
http_requests_total 2
# TYPE pool_size gauge
# HELP pool_size MongoDB Connections pool size
pool_size 365
# TYPE orders summary
# HELP orders Track orders count/total sum
orders_count 4
orders_sum 50
# TYPE http_request_duration_milliseconds histogram
# HELP http_request_duration_milliseconds Http Request execution time
http_request_duration_milliseconds_bucket{method="post",le="100"} 0
http_request_duration_milliseconds_bucket{method="post",le="300"} 1
http_request_duration_milliseconds_bucket{method="post",le="500"} 3
http_request_duration_milliseconds_bucket{method="post",le="750"} 4
http_request_duration_milliseconds_bucket{method="post",le="1000"} 5
http_request_duration_milliseconds_bucket{method="post",le="+Inf"} 6
http_request_duration_milliseconds_count{method="post"} 6
http_request_duration_milliseconds_sum{method="post"} 4350
http_request_duration_milliseconds_bucket{method="get",le="100"} 3
http_request_duration_milliseconds_bucket{method="get",le="300"} 6
http_request_duration_milliseconds_bucket{method="get",le="500"} 7
http_request_duration_milliseconds_bucket{method="get",le="750"} 8
http_request_duration_milliseconds_bucket{method="get",le="1000"} 9
http_request_duration_milliseconds_bucket{method="get",le="+Inf"} 9
http_request_duration_milliseconds_count{method="get"} 9
http_request_duration_milliseconds_sum{method="get"} 2622

API

API can be grouped like this:

Standard Metrics & Registry

All metrics created via new/1 or declare/1. The difference is that new/1 actually wants metric to be new and raises {mf_already_exists, {Registry, Name}, Message} error if it isn't.

Both new/1 and declare/1 accept options as proplist. Common options are:

  • name - metric name, can be an atom or a string (required);
  • help - metric help, string (required);
  • labels - metric labels, label can be an atom or a string (default is []);
  • registry - Prometheus registry for the metric, can be any term. (default is default)

Histogram also accepts buckets option. Please refer to respective modules docs for the more information.

Exposition Formats

General Helpers

Advanced

You will need these modules only if you're writing custom collector for app/lib that can't be instrumented directly.

Build

   $ rebar3 compile

Configuration

Prometheus.erl supports standard Erlang app configuration.

  • default_collectors - List of custom collectors modules to be registered automatically. If undefined list of all modules implementing prometheus_collector behaviour will be used.
  • default_metrics - List of metrics to be registered during app startup. Metric format: {Registry, Metric, Spec} where Registry is registry name, Metric is metric type (prometheus_counter, prometheus_gauge ... etc), Spec is a list to be passed to Metric:register/2.

Collectors & Exporters Conventions

Configuration

All 3d-party libraries should be configured via prometheus app env.

Exproters are responsible for maintianing scrape endpoint. Exporters usually tightly coupled with web server and are singletons. They should understand these keys:

  • path - url for scraping;
  • format - scrape format as module name i.e. prometheus_text_format or prometheus_protobuf_format. Exporter-specific options should be under <exporter_name>_exporter for erlang or <Exporter_name>Exporter for Elixir i.e. PlugsExporter or elli_exporter

Collectors collect integration specific metrics i.e. ecto timings, process informations and so on. Their configuration should be under <collector_name>_collectorfor erlang or <Collector_name>Collector for Elixir i.e. process_collector, EctoCollector and so on.

Naming

For Erlang: prometheus_<name>_collector/prometheus_<name>_exporter.

For Elixir: Prometheus.<name>Collector/Prometheus.<name>Exporter.

Contributing

Sections order:

Types -> Macros -> Callbacks -> Public API -> Deprecations -> Private Parts

install git precommit hook:

   ./bin/pre-commit.sh install

Pre-commit check can be skipped passing --no-verify option to git commit.

License

MIT

Modules

prometheus_buckets
prometheus_collector
prometheus_counter
prometheus_format
prometheus_gauge
prometheus_histogram
prometheus_http
prometheus_mnesia
prometheus_mnesia_collector
prometheus_model_helpers
prometheus_protobuf_format
prometheus_registry
prometheus_summary
prometheus_text_format
prometheus_time
prometheus_vm_memory_collector
prometheus_vm_statistics_collector
prometheus_vm_system_info_collector