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[processor/coldstart] pair cold start spans using faas.invocation_id #2520

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Merged
wpessers merged 1 commit into from
Aug 10, 2026
Merged

[processor/coldstart] pair cold start spans using faas.invocation_id #2520

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2 changes: 1 addition & 1 deletion collector/processor/coldstartprocessor/README.md
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Expand Up @@ -7,7 +7,7 @@
| Distributions | [extension] |

This processor associates cold start information generated by the [telemetryapireceiver](../../receiver/telemetryapireceiver) with incoming span data processed by
the Collector extension. It reads the following of incoming Lambda execution spans identified by the `faas.execution` attribute:
the Collector extension. It reads the following of incoming Lambda execution spans, identified by the `faas.invocation_id` attribute (or `faas.execution`, the name it replaced in semantic conventions v1.19.0):

- trace ID
- parent span ID
Expand Down
3 changes: 2 additions & 1 deletion collector/processor/coldstartprocessor/doc.go
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Expand Up @@ -15,7 +15,8 @@
// Package coldstartprocessor correlates cold start information generated by the telemetryapireceiver
// with incoming span data.
//
// It reads the following of incoming Lambda execution spans identified by the faas.execution attribute:
// It reads the following of incoming Lambda execution spans, identified by the faas.invocation_id
// attribute (or faas.execution, the name it replaced in semantic conventions v1.19.0):
//
// - trace ID
// - parent span ID
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3 changes: 1 addition & 2 deletions collector/processor/coldstartprocessor/go.mod
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Expand Up @@ -12,7 +12,7 @@ require (
go.opentelemetry.io/collector/processor v1.63.0
go.opentelemetry.io/collector/processor/processorhelper v0.157.0
go.opentelemetry.io/collector/processor/processortest v0.157.0
go.opentelemetry.io/collector/semconv v0.128.0
go.opentelemetry.io/otel v1.44.0
go.uber.org/multierr v1.11.0
go.uber.org/zap v1.28.0
)
Expand All @@ -37,7 +37,6 @@ require (
go.opentelemetry.io/collector/pdata/testdata v0.157.0 // indirect
go.opentelemetry.io/collector/pipeline v1.63.0 // indirect
go.opentelemetry.io/collector/processor/xprocessor v0.157.0 // indirect
go.opentelemetry.io/otel v1.44.0 // indirect
go.opentelemetry.io/otel/metric v1.44.0 // indirect
go.opentelemetry.io/otel/sdk v1.44.0 // indirect
go.opentelemetry.io/otel/sdk/metric v1.44.0 // indirect
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2 changes: 0 additions & 2 deletions collector/processor/coldstartprocessor/go.sum
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Expand Up @@ -71,8 +71,6 @@ go.opentelemetry.io/collector/processor/processortest v0.157.0 h1:dtpyoIvbB3VLqZ
go.opentelemetry.io/collector/processor/processortest v0.157.0/go.mod h1:gkRzdmNYfKJAmGCk/x8qDsIavVbNI0wTs+uhN7rY7B0=
go.opentelemetry.io/collector/processor/xprocessor v0.157.0 h1:+WyLGrHwcPk3TK+qt7T8CH+oADEMY4r+U5fIMTBvrAc=
go.opentelemetry.io/collector/processor/xprocessor v0.157.0/go.mod h1:DPmoWlks+CihSRjTGKvPKK6a8bl9mHk8hxthrJ+lvBI=
go.opentelemetry.io/collector/semconv v0.128.0 h1:MzYOz7Vgb3Kf5D7b49pqqgeUhEmOCuT10bIXb/Cc+k4=
go.opentelemetry.io/collector/semconv v0.128.0/go.mod h1:OPXer4l43X23cnjLXIZnRj/qQOjSuq4TgBLI76P9hns=
go.opentelemetry.io/otel v1.44.0 h1:JjwHmHpA4iZ3wBxluu2fbbE7j4kqlE8jXyAyPXH7HqU=
go.opentelemetry.io/otel v1.44.0/go.mod h1:BMgjTHL9WPRlRjL2oZCBTL4whCGtXch2H4BhOPIAyYc=
go.opentelemetry.io/otel/metric v1.44.0 h1:1w0gILTcHdr3YI+ixLyjemwrVnsMURbTZFrSYCdDdmc=
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20 changes: 17 additions & 3 deletions collector/processor/coldstartprocessor/processor.go
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Expand Up @@ -22,10 +22,24 @@ import (
"go.opentelemetry.io/collector/pdata/ptrace"
"go.opentelemetry.io/collector/processor"
"go.opentelemetry.io/collector/processor/processorhelper"
semconv "go.opentelemetry.io/collector/semconv/v1.5.0"
semconvlegacy "go.opentelemetry.io/otel/semconv/v1.18.0"
semconv "go.opentelemetry.io/otel/semconv/v1.25.0"
"go.uber.org/zap"
)

// faasInvocationID reports the invocation identifier of an execution span, looking up both the
// current attribute and the one it replaced.
//
// faas.execution was renamed to faas.invocation_id in semantic conventions v1.19.0. Current
// instrumentations set only the new name, while older ones set only the old name, so both have
// to be accepted for the cold start span to be paired with its execution span.
func faasInvocationID(span ptrace.Span) (pcommon.Value, bool) {
if attr, ok := span.Attributes().Get(string(semconv.FaaSInvocationIDKey)); ok {
return attr, true
}
return span.Attributes().Get(string(semconvlegacy.FaaSExecutionKey))
}

type faasExecution struct {
span ptrace.Span
scope pcommon.InstrumentationScope
Expand All @@ -52,7 +66,7 @@ func (p *coldstartProcessor) processTraces(ctx context.Context, td ptrace.Traces
if p.reported {
return false
}
if attr, ok := span.Attributes().Get(semconv.AttributeFaaSColdstart); ok && attr.Bool() {
if attr, ok := span.Attributes().Get(string(semconv.FaaSColdstartKey)); ok && attr.Bool() {
if p.faasExecution == nil {
sp := ptrace.NewSpan()
p.coldstartSpan = &sp
Expand All @@ -67,7 +81,7 @@ func (p *coldstartProcessor) processTraces(ctx context.Context, td ptrace.Traces
return false
}
}
if _, ok := span.Attributes().Get(semconv.AttributeFaaSExecution); ok {
if _, ok := faasInvocationID(span); ok {
if p.coldstartSpan == nil {
p.faasExecution = &faasExecution{
span: ptrace.NewSpan(),
Expand Down
61 changes: 52 additions & 9 deletions collector/processor/coldstartprocessor/processor_test.go
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Expand Up @@ -33,7 +33,8 @@ import (
"go.opentelemetry.io/collector/pdata/ptrace"
"go.opentelemetry.io/collector/processor/processorhelper"
"go.opentelemetry.io/collector/processor/processortest"
semconv "go.opentelemetry.io/collector/semconv/v1.5.0"
semconvlegacy "go.opentelemetry.io/otel/semconv/v1.18.0"
semconv "go.opentelemetry.io/otel/semconv/v1.25.0"
"go.uber.org/multierr"
)

Expand All @@ -57,7 +58,7 @@ func TestProcessor(t *testing.T) {
input: func() ptrace.Traces {
td := ptrace.NewTraces()
span := td.ResourceSpans().AppendEmpty().ScopeSpans().AppendEmpty().Spans().AppendEmpty()
span.Attributes().PutBool(semconv.AttributeFaaSColdstart, true)
span.Attributes().PutBool(string(semconv.FaaSColdstartKey), true)
return td
}(),
expected: ptrace.NewTraces(),
Expand All @@ -81,7 +82,7 @@ func TestProcessor(t *testing.T) {
input: func() ptrace.Traces {
td := ptrace.NewTraces()
span := td.ResourceSpans().AppendEmpty().ScopeSpans().AppendEmpty().Spans().AppendEmpty()
span.Attributes().PutBool(semconv.AttributeFaaSColdstart, true)
span.Attributes().PutBool(string(semconv.FaaSColdstartKey), true)
span.Attributes().PutBool("faas.initialization", true)
addExecutionSpan(td, executionTraceID)
return td
Expand All @@ -105,7 +106,7 @@ func TestProcessor(t *testing.T) {
td := ptrace.NewTraces()
addExecutionSpan(td, executionTraceID)
span := td.ResourceSpans().AppendEmpty().ScopeSpans().AppendEmpty().Spans().AppendEmpty()
span.Attributes().PutBool(semconv.AttributeFaaSColdstart, true)
span.Attributes().PutBool(string(semconv.FaaSColdstartKey), true)
span.Attributes().PutBool("faas.initialization", true)
return td
}(),
Expand Down Expand Up @@ -144,6 +145,48 @@ func TestProcessor(t *testing.T) {
}
}

// TestPairingByInvocationID covers the current semantic convention attribute. faas.execution was
// renamed to faas.invocation_id in v1.19.0 and current instrumentations set only the new name, so a
// cold start span must still be paired when the execution span carries it.
func TestPairingByInvocationID(t *testing.T) {
c, err := newColdstartProcessor(
nil,
nil,
processortest.NewNopSettings(Type),
)
require.NoError(t, err)

// The cold start span arrives first and is held back until its execution span shows up.
input := ptrace.NewTraces()
span := input.ResourceSpans().AppendEmpty().ScopeSpans().AppendEmpty().Spans().AppendEmpty()
span.Attributes().PutBool(string(semconv.FaaSColdstartKey), true)
output, err := c.processTraces(context.Background(), input)
require.ErrorIs(t, err, processorhelper.ErrSkipProcessingData)
require.Equal(t, 0, output.SpanCount())
require.False(t, c.reported)

executionTraceID := getTraceID()
input = ptrace.NewTraces()
rs := input.ResourceSpans().AppendEmpty()
rs.Resource().Attributes().PutStr("resource-attr", "faas-execution")
ss := rs.ScopeSpans().AppendEmpty()
ss.Scope().SetName("app/execution")
execSpan := ss.Spans().AppendEmpty()
execSpan.SetTraceID(executionTraceID)
execSpan.Attributes().PutStr(string(semconv.FaaSInvocationIDKey), "af9d5aa4-a685-4c5f-a22b-444f80b3cc28")

output, err = c.processTraces(context.Background(), input)
require.NoError(t, err)

// The held cold start span is released alongside the execution span and joins its trace.
require.Equal(t, 2, output.SpanCount())
require.True(t, c.reported)
spans := output.ResourceSpans().At(0).ScopeSpans().At(0).Spans()
for i := 0; i < spans.Len(); i++ {
require.Equal(t, executionTraceID, spans.At(i).TraceID())
}
}

func TestMultipleProcessTraces(t *testing.T) {
c, err := newColdstartProcessor(
nil,
Expand All @@ -164,7 +207,7 @@ func TestMultipleProcessTraces(t *testing.T) {
input = ptrace.NewTraces()
expected = ptrace.NewTraces()
span := input.ResourceSpans().AppendEmpty().ScopeSpans().AppendEmpty().Spans().AppendEmpty()
span.Attributes().PutBool(semconv.AttributeFaaSColdstart, true)
span.Attributes().PutBool(string(semconv.FaaSColdstartKey), true)
span.Attributes().PutBool("faas.initialization", true)
input.CopyTo(expected)
output, err = c.processTraces(context.Background(), input)
Expand All @@ -186,7 +229,7 @@ func TestMultipleProcessTraces(t *testing.T) {
input = ptrace.NewTraces()
expected = ptrace.NewTraces()
span = input.ResourceSpans().AppendEmpty().ScopeSpans().AppendEmpty().Spans().AppendEmpty()
span.Attributes().PutBool(semconv.AttributeFaaSColdstart, true)
span.Attributes().PutBool(string(semconv.FaaSColdstartKey), true)
span.Attributes().PutBool("faas.initialization", true)
input.CopyTo(expected)
output, err = c.processTraces(context.Background(), input)
Expand Down Expand Up @@ -225,17 +268,17 @@ func addExecutionSpan(td ptrace.Traces, id pcommon.TraceID) {
ss.Scope().SetName("app/execution")
span := ss.Spans().AppendEmpty()
span.SetTraceID(id)
span.Attributes().PutStr(semconv.AttributeFaaSExecution, "af9d5aa4-a685-4c5f-a22b-444f80b3cc28")
span.Attributes().PutStr(string(semconvlegacy.FaaSExecutionKey), "af9d5aa4-a685-4c5f-a22b-444f80b3cc28")
}

func executionSpan(span ptrace.Span, id pcommon.TraceID) {
span.SetTraceID(id)
span.Attributes().PutStr(semconv.AttributeFaaSExecution, "af9d5aa4-a685-4c5f-a22b-444f80b3cc28")
span.Attributes().PutStr(string(semconvlegacy.FaaSExecutionKey), "af9d5aa4-a685-4c5f-a22b-444f80b3cc28")
}

func initializationSpan(span ptrace.Span, id pcommon.TraceID) {
span.SetTraceID(id)
span.Attributes().PutBool(semconv.AttributeFaaSColdstart, true)
span.Attributes().PutBool(string(semconv.FaaSColdstartKey), true)
span.Attributes().PutBool("faas.initialization", true)
}

Expand Down
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