fluent-bit OTLP Logs drop Resource and Scope attributes

Bug Report

Describe the bug When you send OTLP logs into Fluent Bit and then send them back out, any Resource or Scope attributes are lost. This is because out_opentelemetry sending logs just initializes and empty resource and scope, thus meaning any data sent in are ignored.

To Reproduce

Rubular link if applicable:
Example log message if applicable: When this OTLP goes in:

{
  "resourceLogs": [
    {
      "resource": {
        "attributes": [
          {
            "key": "host.name",
            "value": {
              "stringValue": "debian-dev-machine"
            }
          },
          {
            "key": "os.type",
            "value": {
              "stringValue": "linux"
            }
          }
        ]
      },
      "scopeLogs": [
        {
          "scope": {},
          "logRecords": [
            {
              "observedTimeUnixNano": "1700497457844514864",
              "body": {
                "stringValue": "here"
              },
              "attributes": [
                {
                  "key": "log.file.name",
                  "value": {
                    "stringValue": "a.txt"
                  }
                }
              ],
              "traceId": "",
              "spanId": ""
            },
            ...
          ]
        }
      ],
      "schemaUrl": "https://opentelemetry.io/schemas/1.6.1"
    }
  ]
}

I passed it into this Fluent Bit config:

[SERVICE]
    Log_level debug
    Flush 1

[INPUT]
    Name opentelemetry
    Listen 127.0.0.1
    Port 6969

[OUTPUT]
    Name     opentelemetry
    Match    *
    Host     127.0.0.1
    Port     4318
    Logs_uri /v1/logs

Then sent it to another local OTel collector and dumped the result to a file. This is the OTLP that came out:

{
  "resourceLogs": [
    {
      "resource": {},
      "scopeLogs": [
        {
          "scope": {},
          "logRecords": [
            {
              "timeUnixNano": "1700497457945114315",
              "body": {
                "kvlistValue": {
                  "values": [
                    {
                      "key": "message",
                      "value": {
                        "stringValue": "here"
                      }
                    }
                  ]
                }
              },
              "attributes": [
                {
                  "key": "log.file.name",
                  "value": {
                    "stringValue": "a.txt"
                  }
                }
              ],
              "traceId": "",
              "spanId": ""
            },
            ...
          ]
        }
      ]
    }
  ]
}

Steps to reproduce the problem: The config I mentioned above, and what I did to reproduce was used an otel collector to read logs from a file and export otlphttp to Fluent Bit, then Fluent Bit output to another otel collector that receives the OTLP and dumps the result to a file.

Expected behavior The data I passed in with OTLP should, at minimum, be the same when it comes out if there is no processing done.

Screenshots

Your Environment

Version used: built from master
Configuration: See above
Environment name and version (e.g. Kubernetes? What version?): normal Debian VM
Server type and version: Debian bullseye VM
Operating System and version: Debian 11
Filters and plugins: See above config

Additional context

This makes Fluent Bit basically unusable for any OTLP-focused pipelines. Losing resource attributes is a particularly big problem, especially because Fluent Bit doesn't appear to provide any way to decorate Resource with attributes to begin with. (That is worth a separate issue probably). I haven't tried traces, but when I tried metrics this wasn't a problem; the data I passed in was what I got out (although all my metric names were prefixed with underscore, which is also definitely a bug, see issue #8083

Nov 20 '23 22:11 braydonk

This is the problematic section: https://github.com/fluent/fluent-bit/blob/5626757c8a580accda3a072d920c63998071b3b7/plugins/out_opentelemetry/opentelemetry.c#L764-L770

Nov 20 '23 22:11 braydonk

There are two issues to fix this issue.

in_opentelemetry ignores resource and scope
out_opentelemetry creates blank resource and scope

I sent a patch to fix issue 1 storing resouce and scope as metadata. https://github.com/fluent/fluent-bit/pull/8294

Jan 21 '24 01:01 nokute78

This issue is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 5 days. Maintainers can add the exempt-stale label.

Apr 21 '24 01:04 github-actions[bot]

Unstale

On Sat, Apr 20, 2024, 6:50 PM github-actions[bot] @.***> wrote:

This issue is stale because it has been open 90 days with no activity. Remove stale label or comment or this will be closed in 5 days. Maintainers can add the exempt-stale label.

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Apr 21 '24 02:04 braydonk

Hi, any updates on this, work arounds , anything. I have same problem, I use k6 to generate logs and sent it to fluentbit incase of http it works as expected and I see full logs but in case of opentelemetry some logs info are missing.