进程不存在不会触发报警

[tzwken]

没有进程存活监控

sum by (groupname) (namedprocess_namegroup_num_procs{groupname='nginx'}) == 0

[SilenceAdele]

• Used absent() function can detection metrics with null value that resulte retrun 1.

absent(sum by (groupname) (namedprocess_namegroup_num_procs{groupname='nginx'})) == 1

• By the way, I guess your process-exporter start command set "--remove-empty-groups=true". when all process were killed in one of process group, the process group will be removed and the related metrics also removed. If "--remove-empty-groups=false" or don't set it，the process group will always exist by default. than, your's alert rule will take effect. please check it.
  sum by (groupname) (namedprocess_namegroup_num_procs{groupname='nginx'}) == 0