FrozenError on Ruby 3.0.0

[TeroPihlaja]

Describe the bug

FrozenError: can't modify frozen String: "" when starting Elastic APM with Ruby 3.0.0

Steps to reproduce

1. Create a project with Ruby 3.0.0 and install Elastic APM.
2. Start
3. On agent startup the following error is generated:

[ElasticAPM] Couldn't establish connection to APM Server:
"#<FrozenError: can't modify frozen String: \"\">"

I patched a backtrace logging to see where it comes from:

[
"/usr/local/rvm/gems/ruby-3.0.0/gems/http-3.3.0/lib/http/response/body.rb:52:in `force_encoding'",
"/usr/local/rvm/gems/ruby-3.0.0/gems/http-3.3.0/lib/http/response/body.rb:52:in `to_s'",
"/usr/local/rvm/gems/ruby-3.0.0/gems/http-3.3.0/lib/http/response.rb:92:in `flush'",
"/usr/local/rvm/gems/ruby-3.0.0/gems/elastic-apm-3.13.0/lib/elastic_apm/transport/connection/http.rb:63:in `request'",
"/usr/local/rvm/gems/ruby-3.0.0/gems/elastic-apm-3.13.0/lib/elastic_apm/transport/connection/http.rb:49:in `post'",
"/usr/local/rvm/gems/ruby-3.0.0/gems/elastic-apm-3.13.0/lib/elastic_apm/transport/connection/http.rb:109:in `block in open_request_in_thread'",
"/usr/local/rvm/gems/ruby-3.0.0/gems/logging-2.3.0/lib/logging/diagnostic_context.rb:474:in `block in create_with_logging_context'"
]

Expected behavior

Elastic APM starts properly and reports to server

Environment

• OS: Linux
• Ruby version: 3.0.0-p0
• Framework and version: Rails 6.1.0
• Agent version: 3.13.0

Additional context

I also created the following issue to http gem: httprb/http#640

[TeroPihlaja]

Looks like I had another dependency pulling in older http gem. Updating to http gem version 4.4.1 seemed to fix this issue.

[mikker]

Was going to suggest that, good that you figured it out on your own 😊 Di you come across anything else ElasticAPM related with the upgrade?

[TeroPihlaja]

Was going to suggest that, good that you figured it out on your own 😊 Di you come across anything else ElasticAPM related with the upgrade?

At least not yet. I did discover some other issues that need more investigation first.