filelogreceiver panics when trace_flags is an empty string

[bgranetzke]

Component(s)

pkg/stanza

What happened?

Description

collector panics when trace parse operator encounters empty string for trace_flags

Steps to Reproduce

My use case is a regex operator which accounts for the log line optionally containing the trace/trace flags at the end.

      - type: regex_parser
        regex: '(?P<traceid>[0-9a-f]+)?[_]?(?P<traceflags>[0-9a-f]+)?$'
        trace:
          trace_id:
            parse_from: attributes.traceid
          trace_flags:
            parse_from: attributes.traceflags

Expected Result

parser gracefully does not try to add trace flags

Actual Result

Panic:
panic: runtime error: index out of range [0] with length 0 goroutine 177 [running]: github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/adapter.convertInto(0xc047473140, {0x90?}) github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza@v0.70.0/adapter/converter.go:338 +0x2b5 github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/adapter.convert(0xc000baef90?) github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza@v0.70.0/adapter/converter.go:284 +0x37 github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/adapter.(*Converter).workerLoop(0xc000617680) github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza@v0.70.0/adapter/converter.go:167 +0x27b created by github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/adapter.(*Converter).Start github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza@v0.70.0/adapter/converter.go:118 +0xf5

panic line in current main:
https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/pkg/stanza/adapter/converter.go#L271

The root cause might be further upstream (passing an empty []byte instead of a nil), but I think some simple defensive programming here makes sense (add a len() check in addition to the nil check)

Collector version

0.70.0

Environment information

No response

OpenTelemetry Collector configuration

No response

Log output

No response

Additional context

No response

[github-actions]

Pinging code owners:

• pkg/stanza: @djaglowski

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[atoulme]

Thanks for the report @bgranetzke, would you be interested in contributing a test case reproducing the problem?

[bgranetzke]

@atoulme Not sure if this is what you meant, but I cut a PR with a unit test which exercised the specific condition and then I fixed the cause.

[bgranetzke]

FYI: I was also able to reproduce the problem when I upgraded the collector version to 0.75.0

panic: runtime error: index out of range [0] with length 0
goroutine 121 [running]:
github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/adapter.convertInto(0xc000000a80, {0xc000418d50?})
github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza@v0.75.0/adapter/converter.go:271 +0x2b5
github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/adapter.(*Converter).workerLoop(0xc000644a50)
github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza@v0.75.0/adapter/converter.go:174 +0x6ac
created by github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza/adapter.(*Converter).Start
github.com/open-telemetry/opentelemetry-collector-contrib/pkg/stanza@v0.75.0/adapter/converter.go:104 +0x112

[crobert-1]

@bgranetzke Thanks for fixing this! Feel free to close this issue if it's in fact resolved.