FrozenError exception raised instantiating agent in Rails 6.1.1

[cbatson]

Using Ruby 3.0 and Rails 6.1.1:

root@3353f515ae84:/gwf/app# bundle exec rails c
/usr/local/bundle/bundler/gems/instrumental_agent-ruby-e6b27a2199d2/lib/instrumental/agent.rb:18: warning: Socket.gethostbyname is deprecated; use Addrinfo.getaddrinfo instead.
Loading development environment (Rails 6.1.1)
irb(main):001:0> require 'instrumental_agent'
=> false
irb(main):002:0> agent = Instrumental::Agent.new('foo', enabled: false)
Traceback (most recent call last):
        2: from (irb):2:in `<main>'
        1: from (irb):2:in `new'
FrozenError (can't modify frozen Array: [Metrician::Middleware::RequestTiming, Rack::ContentLength, ActionDispatch::HostAuthorization, Rack::Sendfile, ActionDispatch::Static, ActionDispatch::Executor, ActiveSupport::Cache::Strategy::LocalCache::Middleware, Rack::Runtime, ActionDispatch::RequestId, ActionDispatch::RemoteIp, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::DebugExceptions, ActionDispatch::ActionableExceptions, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::Migration::CheckPending, Rack::Head, Rack::ConditionalGet, Rack::ETag, Metrician::Middleware::ApplicationTiming])

[cbatson]

Can work around by disabling metrician:

irb(main):003:0> agent = Instrumental::Agent.new('foo', enabled: false, metrician: false)
=> #<Instrumental::Agent:0x00005646207d61f0 @api_key="foo", @host="collector.instrumentalapp.com", @port=80...

[jason-o-matic]

We'll take a look, but off the top of my head does it work if you load the agent earlier in the rails startup process? It looks like something during initialization is freezing the middleware array, so if the agent is loaded before that happens it might work.