vmstat collector metric types

[knweiss]

Two comments regarding the vmstat collector:

1. The node_vmstat_* metrics are currently untyped. Shouldn't most of them use type counter?
2. The following metrics are exceptions, however. AFAIK they should use type gauge (the list may be incomplete - I wouldn't mind if someone double checks):

node_vmstat_nr_free_pages
node_vmstat_nr_alloc_batch
node_vmstat_nr_inactive_anon
node_vmstat_nr_active_anon
node_vmstat_nr_inactive_file
node_vmstat_nr_active_file
node_vmstat_nr_unevictable
node_vmstat_nr_mlock
node_vmstat_nr_anon_pages
node_vmstat_nr_mapped
node_vmstat_nr_file_pages
node_vmstat_nr_dirty
node_vmstat_nr_writeback
node_vmstat_nr_slab_reclaimable
node_vmstat_nr_slab_unreclaimable
node_vmstat_nr_page_table_pages
node_vmstat_nr_kernel_stack
node_vmstat_nr_unstable
node_vmstat_nr_bounce
node_vmstat_nr_vmscan_write
node_vmstat_nr_vmscan_immediate_reclaim
node_vmstat_nr_writeback_temp
node_vmstat_nr_isolated_anon
node_vmstat_nr_isolated_file
node_vmstat_nr_shmem
node_vmstat_nr_anon_transparent_hugepages
node_vmstat_nr_free_cma
node_vmstat_nr_dirty_threshold
node_vmstat_nr_dirty_background_threshold

[brian-brazil]

They're a mix, so rather than having to maintain the list over time we choose instead to just mark everything unypted. This tradeoff is common in exporters. See https://prometheus.io/docs/instrumenting/writing_exporters/#types

[discordianfish]

Agreed that those should be untyped as long as we 'automatically' expose them (-> not by explicitly referring to them). Once we implement #150 this should change though.
Either way, I don't think there is anything to do here, so closing it.