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Add option to inherit service name from the parent span
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@marcotc
marcotc committed Jun 6, 2024
1 parent 66e5b96 commit f45244f
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Showing 11 changed files with 211 additions and 33 deletions.
3 changes: 2 additions & 1 deletion docs/GettingStarted.md
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Expand Up @@ -1913,7 +1913,7 @@ For example, if `tracing.sampling.default_rate` is configured by [Remote Configu
**Available configuration options:**

| Setting | Env Var | Type | Default | Description |
| ------------------------------------------------------ | ------------------------------------------------------- | ------------------------------------- | ---------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
|--------------------------------------------------------|---------------------------------------------------------|---------------------------------------|------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Global** | | | | |
| `agent.host` | `DD_AGENT_HOST` | `String` | `127.0.0.1` | Hostname of Agent to where trace data will be sent. |
| `agent.port` | `DD_TRACE_AGENT_PORT` | `Integer` | `8126` | Port of Agent host to where trace data will be sent. If the [Agent configuration](#configuring-trace-data-ingestion) sets `receiver_port` or `DD_APM_RECEIVER_PORT` to something other than the default `8126`, then `DD_TRACE_AGENT_PORT` or `DD_TRACE_AGENT_URL` must match it. |
Expand All @@ -1935,6 +1935,7 @@ For example, if `tracing.sampling.default_rate` is configured by [Remote Configu
| `tracing.propagation_style` | `DD_TRACE_PROPAGATION_STYLE` | `Array` | `nil` | Distributed tracing propagation formats to extract and inject. See [Distributed Tracing](#distributed-tracing) for more details. |
| `tracing.enabled` | `DD_TRACE_ENABLED` | `Bool` | `true` | Enables or disables tracing. If set to `false` instrumentation will still run, but no traces are sent to the trace agent. |
| `tracing.header_tags` | `DD_TRACE_HEADER_TAGS` | `Array` | `nil` | Record HTTP headers as span tags. See [Applying header tags to root spans][header tags] for more information. |
| `tracing.inherit_parent_service` | | `Bool` | `false` | Inherit the parent span's service name when creating a new child span. |
| `tracing.instrument(<integration-name>, <options...>)` | | | | Activates instrumentation for a specific library. See [Integration instrumentation](#integration-instrumentation) for more details. |
| `tracing.log_injection` | `DD_LOGS_INJECTION` | `Bool` | `true` | Injects [Trace Correlation](#trace-correlation) information into Rails logs if present. Supports the default logger (`ActiveSupport::TaggedLogging`), `lograge`, and `semantic_logger`. |
| `tracing.partial_flush.enabled` | | `Bool` | `false` | Enables or disables partial flushing. Partial flushing submits completed portions of a trace to the agent. Used when tracing instruments long running tasks (e.g. jobs) with many spans. |
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1 change: 1 addition & 0 deletions lib/datadog/tracing/component.rb
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Expand Up @@ -54,6 +54,7 @@ def build_tracer(settings, agent_settings, logger:)
span_sampler: build_span_sampler(settings),
writer: writer,
tags: build_tracer_tags(settings),
inherit_parent_service: settings.tracing.inherit_parent_service
)
end

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15 changes: 15 additions & 0 deletions lib/datadog/tracing/configuration/settings.rb
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Expand Up @@ -144,6 +144,21 @@ def self.extended(base)
o.setter { |header_tags, _| Configuration::HTTP::HeaderTags.new(header_tags) }
end

# Whether spans inherit their parent's service name, when span `service` is not explicitly set.
# If `true`, the spans will use the service name from its parent span.
# If `false`, the spans will use the global service name (`c.service`).
#
# DEV3.0: All other tracer languages inherit the parent's service by default.
# DEV3.0: This option should be set to `true` by default in the next major version,
# DEV3.0: with a removal deprecation warning, then removed in 4.0.
#
# @default `false`
# @return [Boolean]
option :inherit_parent_service do |o|
o.default false
o.type :bool
end

# Enable 128 bit trace id generation.
#
# @default `DD_TRACE_128_BIT_TRACEID_GENERATION_ENABLED` environment variable, otherwise `true`
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17 changes: 13 additions & 4 deletions lib/datadog/tracing/span_operation.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,8 @@ def initialize(
tags: nil,
trace_id: nil,
type: nil,
links: nil
links: nil,
inherit_parent_service: false
)
# Ensure dynamically created strings are UTF-8 encoded.
#
Expand Down Expand Up @@ -90,6 +91,8 @@ def initialize(
# Subscribe :on_error event
@events.on_error.wrap_default(&on_error) if on_error.is_a?(Proc)

@inherit_parent_service = inherit_parent_service

# Start the span with start time, if given.
start(start_time) if start_time
end
Expand Down Expand Up @@ -428,7 +431,8 @@ def message
# it has been finished.
attr_reader \
:events,
:span
:span,
:inherit_parent_service

# Stored only for `service_entry` calculation.
# Use `parent_id` for the effective parent span id.
Expand All @@ -439,6 +443,11 @@ def message
# mutation by reference; when this span is returned,
# we don't want this SpanOperation to modify it further.
def build_span
# Use parent service if no service is set and @inherit_parent_service is set
service = self.service || (@parent&.service if @inherit_parent_service)

service_entry = @parent.nil? || (service && @parent.service != service)

Span.new(
@name,
duration: duration,
Expand All @@ -448,13 +457,13 @@ def build_span
metrics: Core::Utils::SafeDup.frozen_or_dup(metrics),
parent_id: @parent_id,
resource: @resource,
service: @service,
service: service,
start_time: @start_time,
status: @status,
type: @type,
trace_id: @trace_id,
links: @links,
service_entry: parent.nil? || (service && parent.service != service)
service_entry: service_entry
)
end

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11 changes: 8 additions & 3 deletions lib/datadog/tracing/trace_operation.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -70,19 +70,22 @@ def initialize(
sampled: nil,
sampling_priority: nil,
service: nil,
default_service: nil,
profiling_enabled: nil,
tags: nil,
metrics: nil,
trace_state: nil,
trace_state_unknown_fields: nil,
remote_parent: false
remote_parent: false,
inherit_parent_service: false
)
# Attributes
@id = id || Tracing::Utils::TraceId.next_id
@max_length = max_length || DEFAULT_MAX_LENGTH
@parent_span_id = parent_span_id
@sampled = sampled.nil? ? true : sampled
@remote_parent = remote_parent
@inherit_parent_service = inherit_parent_service

# Tags
@agent_sample_rate = agent_sample_rate
Expand All @@ -95,6 +98,7 @@ def initialize(
@sample_rate = sample_rate
@sampling_priority = sampling_priority
@service = service
@default_service = default_service
@profiling_enabled = profiling_enabled
@trace_state = trace_state
@trace_state_unknown_fields = trace_state_unknown_fields
Expand Down Expand Up @@ -169,7 +173,7 @@ def resource_override?
end

def service
@service || (root_span && root_span.service)
@service || (root_span && root_span.service) || @default_service
end

def measure(
Expand Down Expand Up @@ -249,7 +253,8 @@ def build_span(
start_time: start_time,
tags: tags,
trace_id: trace_id,
type: type
type: type,
inherit_parent_service: @inherit_parent_service
)
rescue StandardError => e
Datadog.logger.debug { "Failed to build new span: #{e}" }
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13 changes: 10 additions & 3 deletions lib/datadog/tracing/tracer.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,8 @@ def initialize(
),
span_sampler: Sampling::Span::Sampler.new,
tags: {},
writer: Writer.new
writer: Writer.new,
inherit_parent_service: false
)
@trace_flush = trace_flush
@default_service = default_service
Expand All @@ -68,6 +69,7 @@ def initialize(
@span_sampler = span_sampler
@tags = tags
@writer = writer
@inherit_parent_service = inherit_parent_service
end

# Return a {Datadog::Tracing::SpanOperation span_op} and {Datadog::Tracing::TraceOperation trace_op}
Expand Down Expand Up @@ -327,12 +329,16 @@ def build_trace(digest = nil)
trace_state: digest.trace_state,
trace_state_unknown_fields: digest.trace_state_unknown_fields,
remote_parent: digest.span_remote,
default_service: @default_service,
inherit_parent_service: @inherit_parent_service,
)
else
TraceOperation.new(
hostname: hostname,
profiling_enabled: profiling_enabled,
remote_parent: false,
default_service: @default_service,
inherit_parent_service: @inherit_parent_service,
)
end
end
Expand All @@ -341,12 +347,13 @@ def bind_trace_events!(trace_op)
events = trace_op.send(:events)

events.span_before_start.subscribe do |event_span_op, event_trace_op|
event_trace_op.service ||= @default_service
event_span_op.service ||= @default_service
sample_trace(event_trace_op) if event_span_op && event_span_op.parent_id == 0
end

events.span_finished.subscribe do |event_span, event_trace_op|
# Fallback in case the service was never set
event_span.service ||= @default_service

sample_span(event_trace_op, event_span)
flush_trace(event_trace_op)
end
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2 changes: 2 additions & 0 deletions spec/datadog/core/configuration/components_spec.rb
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Expand Up @@ -425,6 +425,7 @@
end
end
let(:span_sampler) { be_a(Datadog::Tracing::Sampling::Span::Sampler) }
let(:inherit_parent_service) { false }
let(:default_options) do
{
default_service: settings.service,
Expand All @@ -434,6 +435,7 @@
sampler: sampler,
span_sampler: span_sampler,
writer: writer,
inherit_parent_service: inherit_parent_service,
}
end

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31 changes: 31 additions & 0 deletions spec/datadog/tracing/configuration/settings_spec.rb
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Expand Up @@ -284,6 +284,37 @@ def propagation_style_inject
end
end

describe '#inherit_parent_service' do
subject(:inherit_parent_service) { settings.tracing.inherit_parent_service }

it { is_expected.to be false }

context 'when inherit_parent_service' do
before { settings.tracing.inherit_parent_service = value }

context 'is set to true' do
let(:value) { true }

it { is_expected.to be true }
end

context 'is set to false' do
let(:value) { false }

it { is_expected.to be false }
end
end
end

describe '#inherit_parent_service=' do
it 'updates the #inherit_parent_service setting' do
expect { settings.tracing.inherit_parent_service = true }
.to change { settings.tracing.inherit_parent_service }
.from(false)
.to(true)
end
end

describe '#header_tags' do
subject(:header_tags) { settings.tracing.header_tags }

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