Get Linux Available Memory
The following section assumes that you already have Hotrod (possibly deployed on some Bboxes) up and running, for more information related to getting up and running see our Getting Started Guide.
The current state of the system is always reflected in the
/proc file system:
$ head /proc/meminfo MemTotal: 16303688 kB MemFree: 1455276 kB MemAvailable: 11735720 kB Buffers: 1204956 kB Cached: 9583644 kB SwapCached: 0 kB Active: 7984812 kB Inactive: 6185032 kB Active(anon): 3322712 kB Inactive(anon): 584080 kB
The system's best guess on available memory is
MemAvailable, so we will calculate
the percentage available.
Usually when you run a command on a regular interval, you get each new line as a
separate event. But not in this case - you want the full text output (
name: memfree input: exec: command: head /proc/meminfo ignore-line-breaks: true interval: 1s
Can now extract the total (I simply copied the first line and replaced the actual number with a group that captures all digits).
And then continue with a separate
extract to find the available kB. Note that we
did not say
remove: true since we want to keep
_raw alive for two separate
If we did not have
ignore-line-breaks, then the first extract would match the first line,
but the second extract would not pass it through - we needed all these lines in
the same time.
actions: - extract: input-field: _raw pattern: 'MemTotal: (\d+) kB' output-fields: [mem_total] - extract: input-field: _raw pattern: 'MemAvailable: (\d+) kB' output-fields: [mem_available] - convert: - mem_total: num - mem_available: num - script: let: - percent_available: round(100*mem_available/mem_total) - remove: [_raw,mem_total,mem_available] output: write: console
Then it's a matter of converting to numbers, calculating the percentage, and removing unneeded fields.