The stdout filter plugin allows printing to the standard output the data flowed through the filter plugin, which can be very useful while debugging.
The plugin has no configuration parameters, is very simple to use.
$ fluent-bit -i cpu -F stdout -m '*' -o null
We have specified to gather CPU usage metrics and print them out in a human-readable way when they flow through the stdout plugin.
Fluent Bit v1.x.x
* Copyright (C) 2019-2021 The Fluent Bit Authors
* Copyright (C) 2015-2018 Treasure Data
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io
[2021/06/04 14:53:59] [ info] [engine] started (pid=3236719)
[2021/06/04 14:53:59] [ info] [storage] version=1.1.1, initializing...
[2021/06/04 14:53:59] [ info] [storage] in-memory
[2021/06/04 14:53:59] [ info] [storage] normal synchronization mode, checksum disabled, max_chunks_up=128
[2021/06/04 14:53:59] [ info] [sp] stream processor started
[0] cpu.0: [1622789640.379532062, {"cpu_p"=>9.000000, "user_p"=>6.500000, "system_p"=>2.500000, "cpu0.p_cpu"=>8.000000, "cpu0.p_user"=>6.000000, "cpu0.p_system"=>2.000000, "cpu1.p_cpu"=>9.000000, "cpu1.p_user"=>6.000000, "cpu1.p_system"=>3.000000}]
[0] cpu.0: [1622789641.379529426, {"cpu_p"=>22.500000, "user_p"=>18.000000, "system_p"=>4.500000, "cpu0.p_cpu"=>34.000000, "cpu0.p_user"=>30.000000, "cpu0.p_system"=>4.000000, "cpu1.p_cpu"=>11.000000, "cpu1.p_user"=>6.000000, "cpu1.p_system"=>5.000000}]
[0] cpu.0: [1622789642.379544020, {"cpu_p"=>26.500000, "user_p"=>16.000000, "system_p"=>10.500000, "cpu0.p_cpu"=>30.000000, "cpu0.p_user"=>24.000000, "cpu0.p_system"=>6.000000, "cpu1.p_cpu"=>22.000000, "cpu1.p_user"=>8.000000, "cpu1.p_system"=>14.000000}]
[0] cpu.0: [1622789643.379507371, {"cpu_p"=>39.500000, "user_p"=>34.500000, "system_p"=>5.000000, "cpu0.p_cpu"=>52.000000, "cpu0.p_user"=>48.000000, "cpu0.p_system"=>4.000000, "cpu1.p_cpu"=>28.000000, "cpu1.p_user"=>21.000000, "cpu1.p_system"=>7.000000}]
^C[2021/06/04 14:54:04] [engine] caught signal (SIGINT)
[2021/06/04 14:54:04] [ info] [input] pausing cpu.0
[2021/06/04 14:54:04] [ warn] [engine] service will stop in 5 seconds
[2021/06/04 14:54:08] [ info] [engine] service stopped