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[processor/transform] Instrument the transform processor to emit trac…
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…es (open-telemetry#33508)

**Description:** Currently Work in Progress - This PR adds
instrumentation to the ottl statement sequence execution by emitting
traces for statement sequence executions. Each statement execution
within that trace is represented as a child span with the respective
statement as an attribute.

Currently, the generated spans will be child spans of the
`opentelemetry.proto.collector.trace.v1.TraceService/Export` trace, due
to the context provided to the `StatementExecution.Execute()` method.
Alternatively, we can also create a new root span for the statement
sequence execution. Feel free to comment on what option you would prefer
in this case.

As for relating the debug logs to the traces, it seems like exporting
logs is currently not supported for internal observability, as
documented here:
https://github.com/open-telemetry/opentelemetry-collector/blob/1889d589d5933623b4a4a1831379e95ca02225fb/docs/observability.md?plain=1#L123
- If this is in fact possible in the meantime, I appreciate any pointers
towards how this could be done.

**Link to tracking Issue:** open-telemetry#33433 

**Testing:** Tested by running the collector with the
`--feature-gates=telemetry.useOtelWithSDKConfigurationForInternalTelemetry`
feature flag, and the following configuration:

```
receivers:
  otlp:
    protocols:
      grpc:
        endpoint: 0.0.0.0:4317

processors:
  transform:
    error_mode: ignore
    trace_statements:
      - context: span
        statements:
          - keep_matching_keys(attributes, "foo.*")

exporters:
  debug:
    verbosity: detailed
  otlphttp:
    endpoint: ${env:OTLP_ENDPOINT}
    headers:
      Authorization: "Api-Token ${env:API_TOKEN}"

service:
  telemetry:
    traces:
      processors:
        - batch:
            exporter:
              otlp:
                protocol: http/protobuf
                endpoint: ${env:OTLP_ENDPOINT}/v1/traces
                headers:
                  Authorization: "Api-Token ${env:API_TOKEN}"

  pipelines:
    traces:
      receivers: [otlp]
      processors: [transform]
      exporters: [otlphttp, debug]
```

And sending test spans with attributes (to trigger the statement
sequence execution) using the `telemetrygen` CLI:

```
telemetrygen traces --otlp-insecure --traces 1 --status-code Ok --span-duration 1s --telemetry-attributes http.foo=\"value1\" --telemetry-attributes http.bar=\"value2\" --telemetry-attributes foo=\"bar\"
```

**Documentation:** Added a paragraph in the Troubleshooting section of
the README about emitting traces

---------

Signed-off-by: Florian Bacher <florian.bacher@dynatrace.com>
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@bacherfl
bacherfl authored Jul 2, 2024
1 parent e85efb3 commit 5f75137
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27 changes: 27 additions & 0 deletions .chloggen/ottl-emit-traces.yaml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,27 @@
# Use this changelog template to create an entry for release notes.

# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
change_type: enhancement

# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
component: pkg/ottl

# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
note: Emit traces for statement sequence executions to troubleshoot OTTL statements/conditions

# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
issues: [33433]

# (Optional) One or more lines of additional information to render under the primary note.
# These lines will be padded with 2 spaces and then inserted directly into the document.
# Use pipe (|) for multiline entries.
subtext:

# If your change doesn't affect end users or the exported elements of any package,
# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
# Optional: The change log or logs in which this entry should be included.
# e.g. '[user]' or '[user, api]'
# Include 'user' if the change is relevant to end users.
# Include 'api' if there is a change to a library API.
# Default: '[user]'
change_logs: []
18 changes: 18 additions & 0 deletions pkg/ottl/README.md
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Expand Up @@ -151,3 +151,21 @@ service:
2024-05-29T16:38:09.600-0600 debug ottl@v0.101.0/parser.go:268 TransformContext after statement execution {"kind": "processor", "name": "transform", "pipeline": "logs", "statement": "set(instrumentation_scope.attributes[\"test\"], [\"pass\"])", "condition matched": true, "TransformContext": {"resource": {"attributes": {"test": "pass"}, "dropped_attribute_count": 0}, "scope": {"attributes": {"test": ["pass"]}, "dropped_attribute_count": 0, "name": "", "version": ""}, "log_record": {"attributes": {"log.file.name": "test.log"}, "body": "test", "dropped_attribute_count": 0, "flags": 0, "observed_time_unix_nano": 1717022289500721000, "severity_number": 0, "severity_text": "", "span_id": "", "time_unix_nano": 0, "trace_id": ""}, "cache": {}}}
2024-05-29T16:38:09.601-0600 debug ottl@v0.101.0/parser.go:268 TransformContext after statement execution {"kind": "processor", "name": "transform", "pipeline": "logs", "statement": "set(attributes[\"test\"], true)", "condition matched": true, "TransformContext": {"resource": {"attributes": {"test": "pass"}, "dropped_attribute_count": 0}, "scope": {"attributes": {"test": ["pass"]}, "dropped_attribute_count": 0, "name": "", "version": ""}, "log_record": {"attributes": {"log.file.name": "test.log", "test": true}, "body": "test", "dropped_attribute_count": 0, "flags": 0, "observed_time_unix_nano": 1717022289500721000, "severity_number": 0, "severity_text": "", "span_id": "", "time_unix_nano": 0, "trace_id": ""}, "cache": {}}}
```
If configured to do so, the collector also emits traces for the execution of OTTL statement sequences.
These traces contain spans for the execution of each statement, including the statement itself and whether it has
been applied or not. To make use of this, enable the self monitoring of the collector by setting the
`--feature-gates=telemetry.useOtelWithSDKConfigurationForInternalTelemetry` flag, and using the following configuration
to export the traces to e.g. an OTLP API endpoint:

```yaml
service:
telemetry:
traces:
processors:
- batch:
exporter:
otlp:
protocol: http/protobuf
endpoint: ${env:OTLP_ENDPOINT}/v1/traces
```
4 changes: 2 additions & 2 deletions pkg/ottl/go.mod
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,8 @@ require (
go.opentelemetry.io/collector/component v0.104.0
go.opentelemetry.io/collector/pdata v1.11.0
go.opentelemetry.io/collector/semconv v0.104.0
go.opentelemetry.io/otel v1.27.0
go.opentelemetry.io/otel/sdk v1.27.0
go.opentelemetry.io/otel/trace v1.27.0
go.uber.org/goleak v1.3.0
go.uber.org/zap v1.27.0
Expand All @@ -37,10 +39,8 @@ require (
github.com/prometheus/common v0.54.0 // indirect
github.com/prometheus/procfs v0.15.0 // indirect
go.opentelemetry.io/collector/config/configtelemetry v0.104.0 // indirect
go.opentelemetry.io/otel v1.27.0 // indirect
go.opentelemetry.io/otel/exporters/prometheus v0.49.0 // indirect
go.opentelemetry.io/otel/metric v1.27.0 // indirect
go.opentelemetry.io/otel/sdk v1.27.0 // indirect
go.opentelemetry.io/otel/sdk/metric v1.27.0 // indirect
go.uber.org/multierr v1.11.0 // indirect
golang.org/x/sys v0.21.0 // indirect
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64 changes: 60 additions & 4 deletions pkg/ottl/parser.go
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Original file line number Diff line number Diff line change
Expand Up @@ -10,9 +10,18 @@ import (

"github.com/alecthomas/participle/v2"
"go.opentelemetry.io/collector/component"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/codes"
"go.opentelemetry.io/otel/trace"
"go.opentelemetry.io/otel/trace/noop"
"go.uber.org/zap"
)

const (
logAttributeTraceID = "trace_id"
logAttributeSpanID = "span_id"
)

// Statement holds a top level Statement for processing telemetry data. A Statement is a combination of a function
// invocation and the boolean expression to match telemetry for invoking the function.
type Statement[K any] struct {
Expand Down Expand Up @@ -231,6 +240,7 @@ type StatementSequence[K any] struct {
statements []*Statement[K]
errorMode ErrorMode
telemetrySettings component.TelemetrySettings
tracer trace.Tracer
}

type StatementSequenceOption[K any] func(*StatementSequence[K])
Expand All @@ -250,6 +260,10 @@ func NewStatementSequence[K any](statements []*Statement[K], telemetrySettings c
statements: statements,
errorMode: PropagateError,
telemetrySettings: telemetrySettings,
tracer: &noop.Tracer{},
}
if telemetrySettings.TracerProvider != nil {
s.tracer = telemetrySettings.TracerProvider.Tracer("ottl")
}
for _, op := range options {
op(&s)
Expand All @@ -262,20 +276,62 @@ func NewStatementSequence[K any](statements []*Statement[K], telemetrySettings c
// When the ErrorMode of the StatementSequence is `ignore`, errors are logged and execution continues to the next statement.
// When the ErrorMode of the StatementSequence is `silent`, errors are not logged and execution continues to the next statement.
func (s *StatementSequence[K]) Execute(ctx context.Context, tCtx K) error {
s.telemetrySettings.Logger.Debug("initial TransformContext", zap.Any("TransformContext", tCtx))
ctx, sequenceSpan := s.tracer.Start(ctx, "ottl/StatementSequenceExecution")
defer sequenceSpan.End()
s.telemetrySettings.Logger.Debug(
"initial TransformContext",
zap.Any("TransformContext", tCtx),
zap.String(logAttributeTraceID, sequenceSpan.SpanContext().TraceID().String()),
zap.String(logAttributeSpanID, sequenceSpan.SpanContext().SpanID().String()),
)
for _, statement := range s.statements {
_, condition, err := statement.Execute(ctx, tCtx)
s.telemetrySettings.Logger.Debug("TransformContext after statement execution", zap.String("statement", statement.origText), zap.Bool("condition matched", condition), zap.Any("TransformContext", tCtx))
statementCtx, statementSpan := s.tracer.Start(ctx, "ottl/StatementExecution")
statementSpan.SetAttributes(
attribute.KeyValue{
Key: "statement",
Value: attribute.StringValue(statement.origText),
},
)
_, condition, err := statement.Execute(statementCtx, tCtx)
statementSpan.SetAttributes(
attribute.KeyValue{
Key: "condition.matched",
Value: attribute.BoolValue(condition),
},
)
s.telemetrySettings.Logger.Debug(
"TransformContext after statement execution",
zap.String("statement", statement.origText),
zap.Bool("condition matched", condition),
zap.Any("TransformContext", tCtx),
zap.String(logAttributeTraceID, statementSpan.SpanContext().TraceID().String()),
zap.String(logAttributeSpanID, statementSpan.SpanContext().SpanID().String()),
)
if err != nil {
statementSpan.RecordError(err)
errMsg := fmt.Sprintf("failed to execute statement '%s': %v", statement.origText, err)
statementSpan.SetStatus(codes.Error, errMsg)
if s.errorMode == PropagateError {
sequenceSpan.SetStatus(codes.Error, errMsg)
statementSpan.End()
err = fmt.Errorf("failed to execute statement: %v, %w", statement.origText, err)
return err
}
if s.errorMode == IgnoreError {
s.telemetrySettings.Logger.Warn("failed to execute statement", zap.Error(err), zap.String("statement", statement.origText))
s.telemetrySettings.Logger.Warn(
"failed to execute statement",
zap.Error(err),
zap.String("statement", statement.origText),
zap.String(logAttributeTraceID, statementSpan.SpanContext().TraceID().String()),
zap.String(logAttributeSpanID, statementSpan.SpanContext().SpanID().String()),
)
}
} else {
statementSpan.SetStatus(codes.Ok, "statement executed successfully")
}
statementSpan.End()
}
sequenceSpan.SetStatus(codes.Ok, "statement sequence executed successfully")
return nil
}

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