[FEATURE]: Add configuration option to customize log correlation attributes

[masakiq]

Gem Name

datadog

Gem Version(s)

No response

Describe the goal of the feature

Add a configuration option to allow users to select which attributes are included in log correlation output. Currently, Datadog::Tracing.log_correlation outputs all attributes (env, service, version, trace_id, span_id, ddsource), but users should be able to configure which attributes to include.

For example, a configuration like:

Datadog.configure do |c|
  c.tracing.log_injection_attributes = [:trace_id]
  # or
  c.tracing.log_injection_attributes = [:trace_id, :span_id]
end

This would allow users to reduce verbose log output from:

[dd.env=staging dd.service=myapp dd.version=abc123 dd.trace_id=695e73f5000000002247803521dfbe4b dd.span_id=942369122839116 ddsource=ruby]

To a more concise format like:

[dd.trace_id=695e73f5000000002247803521dfbe4b]

Is your feature request related to a problem?

Yes. The current log correlation injection produces verbose log output that significantly increases log volume and storage costs. In many environments, only trace_id is needed for log-to-trace correlation in Datadog, while other attributes like env, service, version, and ddsource are already configured at the log pipeline level or are redundant.

This is particularly problematic for high-throughput applications where the additional characters per log line accumulate to substantial storage overhead.

Describe alternatives you've considered

1. Setting env and version to nil: This only removes those two attributes; service, span_id, and ddsource are still always included.
2. Disabling automatic log injection and implementing custom log formatter: This requires significant custom code and maintenance overhead for each project.
3. Post-processing logs to strip unwanted attributes: This adds complexity to the log pipeline and doesn't address the root cause.

Describe alternatives you've considered

No response

Additional context

The to_log_format method in lib/datadog/tracing/correlation.rb currently hardcodes all attributes:

def to_log_format
  attributes = []
  attributes << "#{LOG_ATTR_ENV}=#{env}" unless env.nil?
  attributes << "#{LOG_ATTR_SERVICE}=#{service}"
  attributes << "#{LOG_ATTR_VERSION}=#{version}" unless version.nil?
  attributes << "#{LOG_ATTR_TRACE_ID}=#{trace_id}"
  attributes << "#{LOG_ATTR_SPAN_ID}=#{span_id}"
  attributes << "#{LOG_ATTR_SOURCE}=#{Core::Logging::Ext::DD_SOURCE}"
  attributes.join(' ')
end

A possible implementation could introduce a new configuration option that filters which attributes are included in the output.

How does Datadog help you?

No response