Prometheus.ex - Prometheus.io Elixir integrations

@deadtrickster , does this give the same metrics as Erlang prometheus.io client?

Hi, it’s not particularly clear what library/protocol you are instrumenting

Hi @deadtrickster. Thanks for all replys.
I use your library, and i need to add label to all metrics. I need add ‘hostname’, and before the response, i set this value (in handler). My question is: exists one configuration for this?: add an label to all default_metrics.

Thanks!,

Hernán-

Hi @deadtrickster!
The problem with {:prometheus_phoenix, "~> 1.2.0"} was not only that 2 metrics were missing in docs. The problem was that until I used 1.2.1 version /metrics page wasn’t showing any data for phoenix.

@deadtrickster thank you for the answers!
I observe the changes on the /metrics page. Just now I left:

config :prometheus, AppWeb.PipelineInstrumenter,
  labels: [:status_class, :method, :host, :scheme, :request_path],
  duration_buckets: [10, 100, 1_000, 10_000, 100_000,
                     5_000_000, 10_000_000, 20_000_000, 30_000_000],

and the metrics still have:

 http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="10.0"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="100.0"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="1.0e3"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="1.0e4"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="1.0e5"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="3.0e5"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="5.0e5"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="7.5e5"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="1.0e6"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="1.5e6"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="2.0e6"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="3.0e6"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="5.0e6"} 0
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="1.0e7"} 1
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="2.0e7"} 1
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="3.0e7"} 1
http_request_duration_microseconds_bucket{status_class="success",method="GET",host="localhost",scheme="http",request_path="/",le="+Inf"} 1
http_request_duration_microseconds_count{status_class="success",method="GET",host="localhost",scheme="http",request_path="/"} 1

Another question, Q4:
I have a different Instrumenter which doesn’t get to /metrics page:

defmodule AppWeb.ExampleInstrumenter do
  use Prometheus.Metric

  @histogram [name: :http_request_duration_ms,
              labels: [:method],
              buckets: [100, 300, 500, 750, 1000],
              help: "Http Request execution time"]

  def instrument(%{time: time, method: method}) do
    Histogram.observe([name: :http_request_duration_ms, labels: [method]], time)
  end
end

It’s included to Endpoint Instrumenters:

config :app, AppWeb.Endpoint,
  instrumenters: [AppWeb.ExampleInstrumenter]

Where else should it go? The /metrics page doesn’t have http_request_duration_ms label.

Thanks again!

Q1: probably I forgot to update the docs, new metrics are for phoenix channels
Q2: because you can have different sets of labels for each instrumenter
Q3: where/how you observe the chnages?

Q1:
I’m using

      {:prometheus_ex, "~> 2.0"},
      {:prometheus_phoenix, "~> 1.2.0"},

and doc for GitHub - prometheus-erl/prometheus-phoenix at v1.2.0 · GitHub states that it has 2 metrics:

• phoenix_controller_call_duration_microseconds - Whole controller pipeline execution time.
• phoenix_controller_render_duration_microseconds - View rendering time.

Instead, the /metrics page shows me

# TYPE phoenix_controller_call_duration_microseconds histogram
# HELP phoenix_controller_call_duration_microseconds Whole controller pipeline execution time in microseconds.
# TYPE phoenix_controller_render_duration_microseconds histogram
# HELP phoenix_controller_render_duration_microseconds View rendering time in microseconds.
# TYPE phoenix_channel_receive_duration_microseconds histogram
# HELP phoenix_channel_receive_duration_microseconds Phoenix channel receive handler time in microseconds
# TYPE phoenix_channel_join_duration_microseconds histogram
# HELP phoenix_channel_join_duration_microseconds Phoenix channel join handler time in microseconds

Where do they come from? They have no values. After using prometheus_phoenix 1.2.1 metrics are the same but WITH values. Where does all that come from?

Q2:

my config for PhoenixInstrumenter:

config :prometheus, AppWeb.PhoenixInstrumenter,
  controller_call_labels: [:controller, :action],
  duration_buckets: [10, 25, 50, 100, 250, 500, 1000, 2500, 5000,
                     10_000, 25_000, 50_000, 100_000, 250_000, 500_000,
                     1_000_000, 2_500_000, 5_000_000, 10_000_000, 20_000_000, 30_000_000],
  registry: :default,
  duration_unit: :microseconds

Why the key is called controller_call_labels? Other sample configs have smth like

config :prometheus, AppWeb.PipelineInstrumenter,
  labels: [:status_class, :method, :host, :scheme, :request_path],

but not controller_call_labels. How is it set?

Q3:
If I add/remove values from duration_buckets: they change after a certain period of time. Are they cached somewhere?

Thanks ahead for the answers!

Starting from version 2.1 Cowboy has special metrics stream handler - cowboy/src/cowboy_metrics_h.erl at master · ninenines/cowboy · GitHub.
Prometheus cowboy integration uses this interface to directly instrument Cowboy now.

And don’t hesitate joining our prometheus channel on elixir-lang Slack team!

Cool thanks @orestis & @deadtrickster, appreciate it, gonna give it a try for our next project .