Hi,
Fluentbit 5.0.3 Windows version, installed as windows service.
Tail and Opensearch plugin is used. Operation is upsert.
Usual config was->log_level=warning, no trace_output
It was enough to see the errors -in other cases-
However there is nothing about why this "warning/error" occurs.
So even i changed it to below settings. It does not give any clue. Literally nothing.
Records are tried indefinitely. Long records are skipped.
Logs are written to Opensearch, it seems fine.
But there is a storage config.
My concern is, it might overflow the storage if such records can not be processed.
In which scenario, fluentbit refuses to log the issue with such config?
-Please ignore the format-
Service:
log_level=trace
Output:
Buffer_Size=False
Trace_Error=On
Trace_Output=On
[2026/08/17 12:57:16.059] [debug] [upstream] KA connection #968 to xxx:9200 is now available
[2026/08/17 12:57:16.059] [debug] [out flush] cb_destroy coro_id=0
[2026/08/17 12:57:16.059] [debug] [task] destroy task=00000185687C59C0 (task_id=1)
[2026/08/17 12:57:16.061] [debug] [out flush] cb_destroy coro_id=0
[2026/08/17 12:57:16.061] [debug] [task] destroy task=00000185687A9540 (task_id=0)
[2026/08/17 12:57:17.029] [debug] [task] created task=00000185687A9540 id=0 OK
[2026/08/17 12:57:17.126] [debug] [output:opensearch:opensearch.3] HTTP Status=200 URI=/_bulk/_bulk
[2026/08/17 12:57:17.128] [debug] [upstream] KA connection #5700 to xxx:9200 is now available
[2026/08/17 12:57:17.128] [debug] [out flush] cb_destroy coro_id=0
[2026/08/17 12:57:17.128] [debug] [retry] new retry created for task_id=0 attempts=1
[2026/08/17 12:57:17.130] [ warn] [engine] failed to flush chunk '5772-1785401914.324505100.flb', retry in 6 seconds: task_id=0, input=storage_backlog.48 > output=opensearch.3 (out_id=3)
…
[2026/08/17 13:02:27.301] [debug] [upstream] KA connection #1224 to xxx:9200 has been assigned (recycled)
[2026/08/17 13:02:27.311] [debug] [http_client] not using http_proxy for header
[2026/08/17 13:02:27.392] [debug] [output:opensearch:opensearch.3] HTTP Status=200 URI=/_bulk/_bulk
[2026/08/17 13:02:27.394] [debug] [upstream] KA connection #1224 to xxx:9200 is now available
[2026/08/17 13:02:27.394] [debug] [out flush] cb_destroy coro_id=13
[2026/08/17 13:02:27.394] [debug] [retry] re-using retry for task_id=0 attempts=14
[2026/08/17 13:02:27.395] [ warn] [engine] failed to flush chunk '5772-1785401914.324505100.flb', retry in 12 seconds: task_id=0, input=storage_backlog.48 > output=opensearch.3 (out_id=3)
Hi,
Fluentbit 5.0.3 Windows version, installed as windows service.
Tail and Opensearch plugin is used. Operation is upsert.
Usual config was->log_level=warning, no trace_output
It was enough to see the errors -in other cases-
However there is nothing about why this "warning/error" occurs.
So even i changed it to below settings. It does not give any clue. Literally nothing.
Records are tried indefinitely. Long records are skipped.
Logs are written to Opensearch, it seems fine.
But there is a storage config.
My concern is, it might overflow the storage if such records can not be processed.
In which scenario, fluentbit refuses to log the issue with such config?
-Please ignore the format-
Service:
log_level=trace
Output:
Buffer_Size=False
Trace_Error=On
Trace_Output=On
[2026/08/17 12:57:16.059] [debug] [upstream] KA connection #968 to xxx:9200 is now available
[2026/08/17 12:57:16.059] [debug] [out flush] cb_destroy coro_id=0
[2026/08/17 12:57:16.059] [debug] [task] destroy task=00000185687C59C0 (task_id=1)
[2026/08/17 12:57:16.061] [debug] [out flush] cb_destroy coro_id=0
[2026/08/17 12:57:16.061] [debug] [task] destroy task=00000185687A9540 (task_id=0)
[2026/08/17 12:57:17.029] [debug] [task] created task=00000185687A9540 id=0 OK
[2026/08/17 12:57:17.126] [debug] [output:opensearch:opensearch.3] HTTP Status=200 URI=/_bulk/_bulk
[2026/08/17 12:57:17.128] [debug] [upstream] KA connection #5700 to xxx:9200 is now available
[2026/08/17 12:57:17.128] [debug] [out flush] cb_destroy coro_id=0
[2026/08/17 12:57:17.128] [debug] [retry] new retry created for task_id=0 attempts=1
[2026/08/17 12:57:17.130] [ warn] [engine] failed to flush chunk '5772-1785401914.324505100.flb', retry in 6 seconds: task_id=0, input=storage_backlog.48 > output=opensearch.3 (out_id=3)
…
[2026/08/17 13:02:27.301] [debug] [upstream] KA connection #1224 to xxx:9200 has been assigned (recycled)
[2026/08/17 13:02:27.311] [debug] [http_client] not using http_proxy for header
[2026/08/17 13:02:27.392] [debug] [output:opensearch:opensearch.3] HTTP Status=200 URI=/_bulk/_bulk
[2026/08/17 13:02:27.394] [debug] [upstream] KA connection #1224 to xxx:9200 is now available
[2026/08/17 13:02:27.394] [debug] [out flush] cb_destroy coro_id=13
[2026/08/17 13:02:27.394] [debug] [retry] re-using retry for task_id=0 attempts=14
[2026/08/17 13:02:27.395] [ warn] [engine] failed to flush chunk '5772-1785401914.324505100.flb', retry in 12 seconds: task_id=0, input=storage_backlog.48 > output=opensearch.3 (out_id=3)