[receiver/filelog] names of files are printed repeatedly to stdout

[andrzej-stencel]

Component(s)

receiver/filelog

What happened?

When using the File Log receiver in v0.124.0, the collector prints out to stdout each tracked file's name, on every poll interval (200ms by default). This means that if the File Log receiver is tracking 3 files, 3 * 5 = 15 lines containing the names of the files will be printed to stdout every second (5 lines for each file).

Steps to Reproduce

1. Run collector with the below config

Expected Result

File names "logs.log", "logs.json", "logs.txt" are not printed to console output.

Actual Result

File names "logs.log", "logs.json", "logs.txt" are printed to console output on every poll (200ms by default).

Collector version

v0.124.0

OpenTelemetry Collector configuration

service:
  pipelines:
    logs:
      receivers:
        - filelog
      exporters:
        - debug
receivers:
  filelog:
    include:
      - logs.*
    exclude:
      - logs.tgz
    start_at: beginning
exporters:
  debug:

Log output

$ otelcol-contrib-0.124.0-linux_amd64 --config 0415-filelog-receiver-bug.yaml
2025-04-15T12:40:05.099+0200    info    [email protected]/service.go:199 Setting up own telemetry...
2025-04-15T12:40:05.099+0200    info    builders/builders.go:26 Development component. May change in the future.
2025-04-15T12:40:05.100+0200    info    [email protected]/service.go:266 Starting otelcol-contrib...     {"Version": "0.124.0", "NumCPU": 20}
2025-04-15T12:40:05.101+0200    info    extensions/extensions.go:41     Starting extensions...
2025-04-15T12:40:05.101+0200    info    adapter/receiver.go:41  Starting stanza receiver
2025-04-15T12:40:05.101+0200    info    [email protected]/service.go:289 Everything is ready. Begin running and processing data.
2025-04-15T12:40:05.303+0200    info    fileconsumer/file.go:265        Started watching file   {"component": "fileconsumer", "path": "logs.json"}
2025-04-15T12:40:05.303+0200    info    fileconsumer/file.go:265        Started watching file   {"component": "fileconsumer", "path": "logs.log"}
2025-04-15T12:40:05.303+0200    info    fileconsumer/file.go:265        Started watching file   {"component": "fileconsumer", "path": "logs.txt"}
logs.txt
logs.json
logs.log
2025-04-15T12:40:05.401+0200    info    Logs    {"resource logs": 1, "log records": 8}
logs.txt
logs.log
logs.json
logs.txt
logs.log
logs.json
logs.txt
logs.log
logs.json
logs.txt
logs.json
logs.log
logs.txt
logs.log
logs.json
logs.txt
logs.json
logs.log
logs.txt
logs.json
logs.log
logs.txt
logs.json
logs.log

Additional context

Caused by this line: https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/v0.124.0/pkg/stanza/fileconsumer/internal/reader/reader.go#L185

Introduced in #39373.

Workaround

The file names are printed to stdout and the collector's logs are printed to stderr by default. This means redirecting stdout is a workaround:

$ otelcol-contrib-0.124.0-linux_amd64 --config 0415-filelog-receiver-bug.yaml > /dev/null
2025-04-15T12:40:54.523+0200    info    [email protected]/service.go:199 Setting up own telemetry...
2025-04-15T12:40:54.523+0200    info    builders/builders.go:26 Development component. May change in the future.
2025-04-15T12:40:54.524+0200    info    [email protected]/service.go:266 Starting otelcol-contrib...     {"Version": "0.124.0", "NumCPU": 20}
2025-04-15T12:40:54.524+0200    info    extensions/extensions.go:41     Starting extensions...
2025-04-15T12:40:54.524+0200    info    adapter/receiver.go:41  Starting stanza receiver
2025-04-15T12:40:54.525+0200    info    [email protected]/service.go:289 Everything is ready. Begin running and processing data.
2025-04-15T12:40:54.726+0200    info    fileconsumer/file.go:265        Started watching file   {"component": "fileconsumer", "path": "logs.json"}
2025-04-15T12:40:54.727+0200    info    fileconsumer/file.go:265        Started watching file   {"component": "fileconsumer", "path": "logs.log"}
2025-04-15T12:40:54.727+0200    info    fileconsumer/file.go:265        Started watching file   {"component": "fileconsumer", "path": "logs.txt"}
2025-04-15T12:40:54.826+0200    info    Logs    {"resource logs": 1, "log records": 8}

[github-actions]

Pinging code owners:

• receiver/filelog: @djaglowski @andrzej-stencel

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