Is it possible to include parent_span_id in auto-instrumented logs?

[gejunqiang]

Description:

Hi OpenTelemetry team,

First, thank you for your work on this incredible instrumentation library!

I’m exploring ways to correlate logs with tracing spans in our Java application. Currently, logs automatically include trace_id and span_id via the logging instrumentation, but parent_span_id is missing. This would be extremely helpful for debugging distributed transactions, as it would allow us to reconstruct the full parent-child span hierarchy directly from logs.

Questions:

• Is there an existing configuration to expose parent_span_id in logs that I might have missed?

• If not, would the team consider adding this as a feature?

Use Case:

When analyzing logs (e.g., in ELK), having parent_span_id would let us:

• Trace a request’s propagation path without querying the tracing backend.

• Identify broken parent-child relationships in complex workflows.

Thank you for your time!

[laurit]

Is there an existing configuration to expose parent_span_id in logs that I might have missed?

no, there isn't

If not, would the team consider adding this as a feature?

It is a bit problematic since the opentelemetry java api provided by https://github.com/open-telemetry/opentelemetry-java that this project uses does not provide a way to get the parent span. To get the parent span one has to go through the sdk classes such as https://github.com/open-telemetry/opentelemetry-java/blob/cc7d0855e7f04e529c794b965e247a86d052426c/sdk/trace/src/main/java/io/opentelemetry/sdk/trace/ReadableSpan.java#L36

[gejunqiang]

finally, i tried like this, but the statementspan instanceof ReadableSpan return false

[laurit]

what do you think about making opentelemetry-sdk-trace a dependency in this project

the agent depends on the sdk, but the library instrumentations don't and shouldn't

finally, i tried like this, but the statementspan instanceof ReadableSpan return false

This could happen when you are using agent and do this test in the application code. Then the span object you see is bridged from the agent ant this bridge does not implement ReadableSpan.

[gejunqiang]

Got it. I've tried a few approaches, but none of them can retrieve the parent_span_id. It seems supporting this would require substantial code changes. Would be great if the team could consider supporting this later. Thanks for your work!

[laurit]

I doubt that we'll be adding this any time soon, but if you so wish you can probably get parent_span_id added to mdc yourself. If you are not using the agent then casting to ReadableSpan should succeed. If you use agent then in the agent extension casting to ReadableSpan should also succeed. If you are using agent and wish to do it in application code then you could use reflection to call

opentelemetry-java-instrumentation/instrumentation/opentelemetry-api/opentelemetry-api-1.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/opentelemetryapi/trace/Bridging.java

Line 72 in 114ae39

public static io.opentelemetry.api.trace.Span toAgentOrNull(Span applicationSpan) {

to unwrap the bridged span and use more reflection to get what you need.

[gejunqiang]

Thanks for the guidance. I'll attempt this method and see how it goes.