Caddy.Metrics.Poller (Caddy v2.3.1)

Periodic metrics collection from Caddy's Prometheus endpoint.

This GenServer periodically fetches metrics from Caddy and emits telemetry events with the collected data.

Configuration

config :caddy,
  metrics_enabled: true,
  metrics_interval: 15_000  # milliseconds

Starting the Poller

# Manual start
Caddy.Metrics.Poller.start_link(interval: 15_000)

# Check if running
Caddy.Metrics.Poller.running?()

# Stop the poller
Caddy.Metrics.Poller.stop()

Telemetry Events

When metrics are collected, the following event is emitted:

[:caddy, :metrics, :collected]

With measurements containing all parsed metric values.

Summary

Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

interval(server \\ __MODULE__)

Get the current interval setting.

last_metrics(server \\ __MODULE__)

Get the last collected metrics.

poll_now(server \\ __MODULE__)

Trigger an immediate metrics collection.

running?(server \\ __MODULE__)

Check if the poller is running.

set_interval(new_interval, server \\ __MODULE__)

Update the polling interval.

start_link(opts \\ [])

Start the metrics poller.

stop(server \\ __MODULE__)

Stop the metrics poller.

Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

See Supervisor.

interval(server \\ MODULE)

@spec interval(GenServer.server()) :: pos_integer()

Get the current interval setting.

last_metrics(server \\ MODULE)

@spec last_metrics(GenServer.server()) :: Caddy.Metrics.t() | nil

Get the last collected metrics.

poll_now(server \\ MODULE)

@spec poll_now(GenServer.server()) :: :ok

Trigger an immediate metrics collection.

running?(server \\ MODULE)

@spec running?(GenServer.server()) :: boolean()

Check if the poller is running.

set_interval(new_interval, server \\ MODULE)

@spec set_interval(pos_integer(), GenServer.server()) :: :ok

Update the polling interval.

start_link(opts \\ [])

@spec start_link(keyword()) :: GenServer.on_start()

Start the metrics poller.

Options

:interval - Polling interval in milliseconds (default: 15000)
:name - Process name (default: Caddy.Metrics.Poller)

stop(server \\ MODULE)

@spec stop(GenServer.server()) :: :ok

Stop the metrics poller.