How to monitor memory available?

[undersound]

I want to monitor memory usage in relation to total memory

This is my input file

    - name: mem
      tag: metrics.memory
      interval_sec: 30
      interval_nsec: 0

I am running:

me@me:~$` docker exec fluent-bit /fluent-bit/bin/fluent-bit -i mem -t memory -o stdout -m '*'
Fluent Bit v4.0.9
* Copyright (C) 2015-2025 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

[2025/09/17 07:09:17] [ info] [fluent bit] version=4.0.9, commit=5ab8f149ee, pid=72
[2025/09/17 07:09:17] [ info] [storage] ver=1.5.3, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2025/09/17 07:09:17] [ info] [simd    ] SSE2
[2025/09/17 07:09:17] [ info] [cmetrics] version=1.0.5
[2025/09/17 07:09:17] [ info] [ctraces ] version=0.6.6
[2025/09/17 07:09:17] [ info] [input:mem:mem.0] initializing
[2025/09/17 07:09:17] [ info] [input:mem:mem.0] storage_strategy='memory' (memory only)
[2025/09/17 07:09:17] [ info] [sp] stream processor started
[2025/09/17 07:09:17] [ info] [engine] Shutdown Grace Period=5, Shutdown Input Grace Period=2
[2025/09/17 07:09:17] [ info] [output:stdout:stdout.0] worker #0 started
**[0] memory: [[1758093270.559195270, {}], {"Mem.total"=>1973764, "Mem.used"=>1880304, "Mem.free"=>93460, "Swap.total"=>2097148, "Swap.used"=>587632, "Swap.free"=>1509516}]**

When I run:
free -h

Type	Total	Used	Free	Shared	Buff/Cache	Available
Mem	1.9Gi	929Mi	88Mi	114Mi	909Mi	697Mi
Swap	2.0Gi	573Mi	1.4Gi	–	–	–

Is it possible to grab the available memory somehow with fluentbit?

[patrick-stephens]

You probably want actual metrics rather than logs as metrics - the node exporter plugin may be better: https://docs.fluentbit.io/manual/data-pipeline/inputs/node-exporter-metrics

There's a few other input plugins listed you can consider too so I'd check the docs.