Ruby: Configure logs in context

Logs in context for the Ruby agent connects your logs and APM data in New Relic. Bringing all of this data together in a single tool helps you quickly get to the root cause of an issue and find the log lines that you need to identify and resolve a problem.

Set up your Ruby app

To enable logs in context for APM apps monitored by Ruby:

Make sure you have already set up logging in New Relic. This includes configuring a supported log forwarder that collects your application logs and extends the metadata that is forwarded to New Relic.
Install or update to the latest Ruby agent version, and enable distributed tracing. Use Ruby agent version 6.7.0 or higher for logs in context.
For Rails applications, use a supported Rails version.
Configure logs in context for Ruby.

Rails logging is controlled by two components:

A logger you can customize by setting config.logger
A log formatter you can customize by setting config.log_formatter)
In most cases, you should configure logs in context by setting config.log_formatter to the DecoratingFormatter in your Rails application. For more information about Rails configuration, see the rubyonrails.org documentation.
In your application's config, require newrelic_rpm, then add the following line:
```
module ________
  class Application < Rails::Application

  ...

  config.log_formatter = ::NewRelic::Agent::Logging::DecoratingFormatter.new
  end
end
```
This configuration uses the New Relic formatter for log messages, but the remaining configuration is provided by the other Rails settings.

If setting the log_formatter option doesn't meet your needs, replace the entire Rails logger with an instance of the New Relic logger. Provide the parameters to the logger's constructor, like this:

module ________
  class Application < Rails::Application

    ...

    config.logger = ::NewRelic::Agent::Logging::DecoratingLogger.new(
    "log/application.log", #etc...
    )
  end
end

For non-Rails applications, use the DecoratingLogger in place of the Ruby standard ::Logger, like this:

logger = ::NewRelic::Agent::Logging::DecoratingLogger.new(
  'log/application.log', #etc...
)
...

logger.info(...)

The DecoratingLogger is a drop-in replacement for the Ruby standard ::Logger. Their constructors accept the same parameters.

To use our logging extension with a different logging implementation or with your own custom logger, use the DecoratingFormatter. For example:

module ________
  class Application < Rails::Application

    ...

    config.logger = ::YourCustomLoggerImplementation.new(
      $stdout,
      formatter: ::NewRelic::Agent::Logging::DecoratingFormatter.new
    )
  end
end

To verify that you have configured the log appender correctly, run your application, then check your logs data in New Relic One using the query operator has:span.id has:trace.id.

If everything is configured correctly and your data is being forwarded to New Relic with the enriched metadata, your logs should now be emitted as JSON and contain trace.id and span.id fields.

If you have configured your logging in /config/application.rb or in /config/environments/development.rb, run your application locally and check its logging output. You should see some output like this:

{"entity.name":"your_app_name","entity.type":"SERVICE","hostname":"79bcbf8d","trace.id":"79bcbf8d","span.id":"00fc7d46","timestamp":1567701375543,"message":"example log message one","log.level":"DEBUG"}
{"entity.name":"your_app_name","entity.type":"SERVICE","hostname":"79bcbf8d","trace.id":"79bcbf8d","span.id":"6754870b","timestamp":1567702843604,"message":"example log message two","log.level":"DEBUG"}

Troubleshooting

If you don't see log data in the UI, follow the troubleshooting procedures. Also, if you see JSON logs in your application's output, but your query does not return logs, check your log forwarder.

If the logs from your application are not formatted in JSON with fields like trace.id and span.id, there may be a problem with your log forwarding extension. In this situation:

Check that the application is using a supported logging framework.
Check that your logging configuration has been applied to all the environments where you want to forward and enrich the log data being sent to New Relic.
Check that another logger is not configured later in your application's configuration.

Logs in context for Ruby does not support tagged logging. If you are initializing your logger with a log_tags argument, your custom tags may not appear on the final version of your logs.

What's next?

After you set up APM logs in context, make the most of your logging data:

Explore the logging data across your platform with our Logs UI.
See your logs in context of your app's performance in the APM UI. Troubleshoot errors with distributed tracing, stack traces, application logs, and more.
Get deeper visibility into both your application and your platform performance data by forwarding your logs with our infrastructure monitoring agent. Review your infrastructure logs in the UI.
Set up alerts.
Query your data and create dashboards.

Set up your Ruby app

Standard Ruby on Rails configuration

Incompatible gems

Rails advanced configuration

Ruby configuration without Rails

Lograge configuration

Other logging extensions

Troubleshooting

What's next?