Why missing log in tail input plugin when rotate file

[myabcc17]

Bug Report

Describe the bug
Logs before or after the file is rotated are not tracked.
Rotate_Wait, Refresh_Interval is the default value, but this amount was expected to be sufficiently tracked.

But there are untraceable numbers in between.

why is fluent-bit like this? Is that the intended move?

In real business logic, larger files are rotated every 5 minutes, but we tested them like this to reproduce similar issues in simple situations.

To Reproduce

• Steps to reproduce the problem:

1. Run fluent-bit with tail input plugin for '/logs/test' file
2. Exec below script for collect log.
   it is overwrite the file every multiple of 10 to imitate lotate file. and other numbers are added to the file.

#!/bin/bash

for i in {1..50}
do
  if (( $i % 10 == 0 ))
  then
     echo "Overwrite: $i" > /logs/test
  else
    echo "Append: $i" >> /logs/test
  fi
done

Expected behavior
Fluent-bit must be able to log all numbers from 1 to 50.

Screenshots
However, if you look at the log before or after the file is rotated, there are numbers that are not logged.

Why did you do this?

2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 events: IN_MODIFY
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 file truncated /logs/test
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 events: IN_MODIFY
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 file truncated /logs/test
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 events: IN_MODIFY
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 events: IN_MODIFY
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 file truncated /logs/test
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 events: IN_MODIFY
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 events: IN_MODIFY
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 file truncated /logs/test
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 events: IN_MODIFY
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 events: IN_MODIFY
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 events: IN_MODIFY
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 file truncated /logs/test
[2024/11/12 08:44:22] [debug] [input:tail:tail.0] inode=39457440 events: IN_MODIFY
[2024/11/12 08:44:22] [debug] [task] created task=0x7f5890a5c820 id=0 OK
[2024/11/12 08:44:22] [debug] [task] destroy task=0x7f5890a5c820 (task_id=0)
[0] tlog: [1731401062.256527812, {"log"=>"Append: 1"}]
[1] tlog: [1731401062.256531118, {"log"=>"Append: 2"}]
[2] tlog: [1731401062.256531522, {"log"=>"Append: 3"}]
[3] tlog: [1731401062.256531924, {"log"=>"Append: 4"}]
[4] tlog: [1731401062.256532362, {"log"=>"Append: 5"}]
[5] tlog: [1731401062.256532763, {"log"=>"Append: 6"}]
[6] tlog: [1731401062.256533256, {"log"=>"Append: 7"}]
[7] tlog: [1731401062.256533679, {"log"=>"Append: 8"}]
[8] tlog: [1731401062.256534102, {"log"=>"Append: 9"}]
[9] tlog: [1731401062.256756323, {"log"=>"Overwrite: 10"}]
[10] tlog: [1731401062.256756975, {"log"=>"Append: 11"}]
[11] tlog: [1731401062.256757431, {"log"=>"Append: 12"}]
[12] tlog: [1731401062.256757882, {"log"=>"Append: 13"}]
[13] tlog: [1731401062.256758328, {"log"=>"Append: 14"}]
[14] tlog: [1731401062.256758777, {"log"=>"Append: 15"}]
[15] tlog: [1731401062.256759175, {"log"=>"Append: 16"}]
[16] tlog: [1731401062.256759594, {"log"=>"Append: 17"}]
[17] tlog: [1731401062.261444819, {"log"=>"Overwrite: 20"}]
[18] tlog: [1731401062.261447270, {"log"=>"Append: 21"}]
[19] tlog: [1731401062.261447682, {"log"=>"Append: 22"}]
[20] tlog: [1731401062.261448116, {"log"=>"Append: 23"}]
[21] tlog: [1731401062.261448512, {"log"=>"Append: 24"}]
[22] tlog: [1731401062.261449004, {"log"=>"Append: 25"}]
[23] tlog: [1731401062.261599735, {"log"=>"Overwrite: 30"}]
[24] tlog: [1731401062.261600563, {"log"=>"Append: 31"}]
[25] tlog: [1731401062.261601020, {"log"=>"Append: 32"}]
[26] tlog: [1731401062.261601472, {"log"=>"Append: 33"}]
[27] tlog: [1731401062.261640819, {"log"=>"Append: 34"}]
[28] tlog: [1731401062.261641251, {"log"=>"Append: 35"}]
[29] tlog: [1731401062.261687548, {"log"=>"Append: 36"}]
[30] tlog: [1731401062.261687972, {"log"=>"Append: 37"}]
[31] tlog: [1731401062.261688422, {"log"=>"Append: 38"}]
[32] tlog: [1731401062.261766004, {"log"=>"Overwrite: 40"}]
[33] tlog: [1731401062.261766439, {"log"=>"Append: 41"}]
[34] tlog: [1731401062.261802793, {"log"=>"Append: 42"}]
[35] tlog: [1731401062.261803225, {"log"=>"Append: 43"}]
[36] tlog: [1731401062.261848015, {"log"=>"Append: 44"}]
[37] tlog: [1731401062.261848442, {"log"=>"Append: 45"}]
[38] tlog: [1731401062.261891502, {"log"=>"Append: 46"}]
[39] tlog: [1731401062.261891934, {"log"=>"Append: 47"}]
[40] tlog: [1731401062.261892390, {"log"=>"Append: 48"}]
[41] tlog: [1731401062.261926407, {"log"=>"Append: 49"}]
[42] tlog: [1731401062.262008508, {"log"=>"Overwrite: 50"}]

Your Environment

• Version used: amazon/aws-for-fluent-bit:2.10.0
• Configuration:

/fluent-bit/etc/fluent-bit.conf

[SERVICE]
	Flush 1
[INPUT]
	Name tail
	Path /test
	Tag tlog
[OUTPUT]
	Name stdout
	Match tlog

• Environment name and version (e.g. Kubernetes? What version?):
• Server type and version: Local docker run.
• Operating System and version: Ubuntu 22.0.4
• Filters and plugins: Tail (Input plugin)

Additional context

[patrick-stephens]

Please use the latest OSS version - you're using the AWS version which is a custom build of 1.9 series.

[myabcc17]

Please use the latest OSS version - you're using the AWS version which is a custom build of 1.9 series.

@patrick-stephens
Same issue occurred in fluent/fluent-bit:latest image. It has 3.1.10 version.