SetAttributes/AddAttributes truncate strings down to 0-length

[gquintard]

Description

otel/sdk/log.SetAttributes and otel/sdk/log.AddAttributes (what's the difference between the two, by the way?) are essentially useless when give a string because Record.attributeValueLengthLimit default to 0 and isn't public. So all strings used as attributes are truncated down to the empty string.

Environment

• OS: BTW I use Arch
• Architecture: linux/amd64
• Go Version: 1.22.3
• opentelemetry-go version: https://pkg.go.dev/go.opentelemetry.io/otel/sdk/[email protected]

Steps To Reproduce

         record := sdklog.Record{}
          record.SetAttributes(apilog.String("foo", "bar")) 
          record.WalkAttributes( func(kv apilog.KeyValue) bool { 
                          fmt.Printf("%+v: %+v\n",kv.Key, kv.Value) 
                          return true
                  })

You'll see a sad foo: with no bar in sight

Expected behavior

Having a sensible default for the string limit and/or a way to set it would be nice

[pellared]

You are not supposed to create sdklog.Record{} by yourself. Why would you do it?

[gquintard]

ah, might be pebcak then. In short, I didn't see anything to create them in https://pkg.go.dev/go.opentelemetry.io/otel/sdk/[email protected]

The long version is that I'm writing an exporter for varnish logs, meaning I ingest logs from stdin (or from a file) and push them to otel, so the Logger seemed overkill and just creating a Record to feed to the Exporter seemed a lot simpler?

[pellared]

The long version is that I'm writing an exporter for varnish logs, meaning I ingest logs from stdin (or from a file) and push them to otel

You should supposed to create a "log bridge" that uses https://pkg.go.dev/go.opentelemetry.io/otel/log to push logs to otel. You can take a look at e.g. otellogrus for reference.

Related issue: open-telemetry/opentelemetry-go-contrib#5947

[gquintard]

thank you, I'll have a look at this and will close the issue.

[pavel-raykov]

Sorry, there is another case where creating a standalone sdklog.Record could be useful:

By default, the logs are emitted with the Emit method which does not return any status, i.e., the caller does not have any feedback on whether the log has been delivered or not. There is alternative method https://pkg.go.dev/go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp#Exporter.Export which actually takes sdklog.Record as input, so it would be useful if it were possible to construct sdklog.Record with custom attributeValueLengthLimit and pass it to the Export function.

Could you please comment if this makes sense?