panel/config/puma.rb

# frozen_string_literal: true

# Puma can serve each request in a thread from an internal thread pool.
# The `threads` method setting takes two numbers: a minimum and maximum.
# Any libraries that use thread pools should be configured to match the
# maximum value specified for Puma. Default is set to 5 threads for
# minimum and maximum; this matches the default thread size of Active
# Record.
#
threads_count = ENV.fetch('RAILS_MAX_THREADS') { 1 }
threads threads_count, threads_count

# Specifies the `port` that Puma will listen on to receive requests;
# default is 3000.
#
port        ENV.fetch('PORT') { 3000 }

# Specifies the `environment` that Puma will run in.
#
environment ENV.fetch('RAILS_ENV') { 'development' }

# Specifies the number of `workers` to boot in clustered mode.  Workers
# are forked webserver processes. If using threads and workers together
# the concurrency of the application would be max `threads` * `workers`.
# Workers do not work on JRuby or Windows (both of which do not support
# processes).
#
workers ENV.fetch('WEB_CONCURRENCY') { 2 }

# Use the `preload_app!` method when specifying a `workers` number.
# This directive tells Puma to first boot the application and load code
# before forking the application. This takes advantage of Copy On Write
# process behavior so workers use less memory.
#
preload_app!

# Allow puma to be restarted by `rails restart` command.
plugin :tmp_restart

pidfile 'tmp/puma.pid'

# If you are preloading your application and using Active Record, it's
# recommended that you close any connections to the database before workers
# are forked to prevent connection leakage.
#
before_fork do
  ActiveRecord::Base.connection_pool.disconnect! if defined?(ActiveRecord)
end

# The code in the `on_worker_boot` will be called if you are using
# clustered mode by specifying a number of `workers`. After each worker
# process is booted, this block will be run. If you are using the `preload_app!`
# option, you will want to use this block to reconnect to any threads
# or connections that may have been created at application boot, as Ruby
# cannot share connections between processes.
#
on_worker_boot do
  ActiveRecord::Base.establish_connection if defined?(ActiveRecord)

  if Rails.env.production?
    require 'prometheus_exporter/instrumentation'
    PrometheusExporter::Instrumentation::ActiveRecord.start(custom_labels: { type: 'puma_worker' }, config_labels: %i[database host])
    PrometheusExporter::Instrumentation::Puma.start
    PrometheusExporter::Instrumentation::Process.start(type: 'web')
  end
end