[receiver/filelog] record numbers are incorrect when `header` is configured

[andrzej-stencel]

Component(s)

receiver/filelog

What happened?

Description

Configuring the header option for the File Log receiver together with include_file_record_number causes the reported record numbers to be higher than they should be. This happens even when there are no header lines in the file.

Steps to Reproduce (input file with header)

1. Prepare input file

   cat > logs.txt <<EOF
   heredoc> #xyz
   heredoc> my-log
   heredoc> EOF

2. Run the collector with the below config otelcol-contrib --config config.yaml

Expected Result

I would expect the "my-log" log to have log.file.record_number equal to 1.

Actual Result

The log has log.file.record_number equal to 3.

The output from Debug exporter shows the following log:

my-log log.file.name=logs.txt log.file.record_number=3 headerattr=xyz

Steps to Reproduce (input file without header)

1. Prepare input file

   cat > logs.txt <<EOF
   heredoc> my-log
   heredoc> EOF

2. Run the collector with the below config otelcol-contrib --config config.yaml

Expected Result

I would expect the "my-log" log to have log.file.record_number equal to 1.

Actual Result

The log has log.file.record_number equal to 2.

The output from Debug exporter shows the following log:

my-log log.file.name=logs.txt log.file.record_number=2

Collector version

v0.111.0

Environment information

No response

OpenTelemetry Collector configuration

exporters:
  debug:
    verbosity: normal
receivers:
  filelog:
    header:
      metadata_operators:
        - type: regex_parser
          regex: ^#(?P<headerattr>\S+)$
      pattern: ^#
    include:
      - logs.txt
    include_file_record_number: true
    start_at: beginning
service:
  pipelines:
    logs:
      exporters:
        - debug
      receivers:
        - filelog

Log output

2024-10-18T15:42:50.737+0200    info    service@v0.111.0/service.go:136 Setting up own telemetry...
2024-10-18T15:42:50.737+0200    info    telemetry/metrics.go:70 Serving metrics {"address": "localhost:8888", "metrics level": "Normal"}
2024-10-18T15:42:50.737+0200    info    builders/builders.go:26 Development component. May change in the future.        {"kind": "exporter", "data_type": "logs", "name": "debug"}
2024-10-18T15:42:50.739+0200    info    service@v0.111.0/service.go:208 Starting otelcol-contrib...     {"Version": "0.111.0", "NumCPU": 20}
2024-10-18T15:42:50.739+0200    info    extensions/extensions.go:39     Starting extensions...
2024-10-18T15:42:50.739+0200    info    adapter/receiver.go:47  Starting stanza receiver        {"kind": "receiver", "name": "filelog", "data_type": "logs"}
2024-10-18T15:42:50.740+0200    info    service@v0.111.0/service.go:234 Everything is ready. Begin running and processing data.
2024-10-18T15:42:50.940+0200    info    fileconsumer/file.go:256        Started watching file   {"kind": "receiver", "name": "filelog", "data_type": "logs", "component": "fileconsumer", "path": "logs.txt"}
2024-10-18T15:42:51.041+0200    info    LogsExporter    {"kind": "exporter", "data_type": "logs", "name": "debug", "resource logs": 1, "log records": 1}
2024-10-18T15:42:51.041+0200    info    my-log log.file.name=logs.txt log.file.record_number=3 headerattr=xyz
        {"kind": "exporter", "data_type": "logs", "name": "debug"}

Additional context

No response

[github-actions]

Pinging code owners:

• receiver/filelog: @djaglowski

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