Class: Datadog::Tracing::Distributed::Baggage

Inherits:
Object
  • Object
show all
Defined in:
lib/datadog/tracing/distributed/baggage.rb

Overview

W3C Baggage propagator implementation. The baggage header is propagated through ‘baggage`.

See Also:

Constant Summary collapse

BAGGAGE_KEY = 
'baggage'
DD_TRACE_BAGGAGE_MAX_ITEMS = 
64
DD_TRACE_BAGGAGE_MAX_BYTES = 
8192
BAGGAGE_TAG_KEYS_MATCH_ALL = 
['*'].freeze
SAFE_CHARACTERS_KEY = 
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789$!#&'*+-.^_`|~"
SAFE_CHARACTERS_VALUE = 
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789$!#&'()*+-./:<>?@[]^_`{|}~"

Instance Method Summary collapse

Constructor Details

#initialize(fetcher:, baggage_key: BAGGAGE_KEY, baggage_tag_keys: ::Datadog.configuration.tracing.baggage_tag_keys) ⇒ Baggage

Returns a new instance of Baggage.



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# File 'lib/datadog/tracing/distributed/baggage.rb', line 24

def initialize(
  fetcher:,
  baggage_key: BAGGAGE_KEY,
  baggage_tag_keys: ::Datadog.configuration.tracing.baggage_tag_keys
)
  @baggage_key = baggage_key
  @fetcher = fetcher
  @baggage_tag_keys = baggage_tag_keys
end

Instance Method Details

#extract(data) ⇒ Object 



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# File 'lib/datadog/tracing/distributed/baggage.rb', line 84

def extract(data)
  fetcher = @fetcher.new(data)
  data = fetcher[@baggage_key]
  return unless data

  baggage = parse_baggage_header(fetcher[@baggage_key])
  return unless baggage

  # Convert selected baggage items to span tags based on configuration
  baggage_tags = build_baggage_tags(baggage)

  # Record telemetry for successful extraction only if baggage is not empty
  unless baggage.empty?
    record_telemetry_metric('context_header_style.extracted', 1, {'header_style' => 'baggage'})
  end

  TraceDigest.new(
    baggage: baggage,
    trace_distributed_tags: baggage_tags
  )
end

#inject!(digest, data) ⇒ Object 



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# File 'lib/datadog/tracing/distributed/baggage.rb', line 34

def inject!(digest, data)
  return if digest.nil? || digest.baggage.nil?

  baggage_items = digest.baggage.reject { |k, v| k.nil? || v.nil? }
  return if baggage_items.empty?

  begin
    if baggage_items.size > DD_TRACE_BAGGAGE_MAX_ITEMS
      ::Datadog.logger.warn("Baggage item limit (#{DD_TRACE_BAGGAGE_MAX_ITEMS}) exceeded, dropping excess items")
      # Record telemetry for item count truncation
      record_telemetry_metric(
        'context_header.truncated',
        1,
        {'header_style' => 'baggage', 'truncation_reason' => 'baggage_item_count_exceeded'}
      )
      baggage_items = baggage_items.first(DD_TRACE_BAGGAGE_MAX_ITEMS)
    end

    encoded_items = []
    total_size = 0

    baggage_items.each do |key, value|
      item = "#{encode_item(key, SAFE_CHARACTERS_KEY)}=#{encode_item(value, SAFE_CHARACTERS_VALUE)}"
      item_size = item.bytesize + (encoded_items.empty? ? 0 : 1) # +1 for comma if not first item
      if total_size + item_size > DD_TRACE_BAGGAGE_MAX_BYTES
        ::Datadog.logger.warn("Baggage header size (#{DD_TRACE_BAGGAGE_MAX_BYTES}) exceeded, dropping excess items")
        # Record telemetry for byte count truncation
        record_telemetry_metric(
          'context_header.truncated',
          1,
          {'header_style' => 'baggage', 'truncation_reason' => 'baggage_byte_count_exceeded'}
        )
        break # stop adding items when size limit is reached
      end
      encoded_items << item
      total_size += item_size
    end

    # edge case where a single item is too large
    return if encoded_items.empty?

    data[@baggage_key] = encoded_items.join(',')

    # Record telemetry for successful injection
    record_telemetry_metric('context_header_style.injected', 1, {'header_style' => 'baggage'})
  rescue => e
    ::Datadog.logger.warn("Failed to encode and inject baggage header: #{e.class}: #{e}")
  end
end