Do you need to modify the metrics collected from Linux by Percona Monitoring and Management (PMM)? In this blog post we will see how to enable, disable, and update collected metrics on PMM’s linux:metrics exporter.
Using a custom list of metrics
Let’s now suppose we are not yet collecting any metrics on our desired client server, and we want to enable only the following: diskstats, meminfo, netdev and vmstat. We can use the following command:
pmm-admin add linux:metrics -- -collectors.enabled=diskstats,meminfo,netdev,vmstat
So, in order to enable or disable the functionality we want, we need to modify the collectors.enabled list accordingly. In the following online documentation page, we are able to find all collectors supported:
In this way, by adding or removing items from the collectors.enabled list, we can choose which functionality will be set in our PMM linux:metrics collectors.
Checking list of metrics used
We can use the ps aux command to check the collectors list that applies at any given time. Let’s see this in practical terms. After running the previous command, we should expect to see the following:
shell> ps aux | grep node_exporter
root 20450 3.2 0.0 1660248 15924 ? Sl 13:48 0:13 /usr/local/percona/pmm-client/node_exporter -collectors.enabled=diskstats,filefd,filesystem,loadavg,meminfo,netdev,netstat,stat,time,uname,vmstat,meminfo_numa -web.listen-address=10.10.8.141:42000 -web.auth-file=/usr/local/percona/pmm-client/pmm.yml -web.ssl-cert-file=/usr/local/percona/pmm-client/server.crt -web.ssl-key-file=/usr/local/percona/pmm-client/server.key -collectors.enabled=diskstats,meminfo,netdev,vmstat
Note: there is currently a bug where you will see duplicate entries when using custom collectors. We are tracking this under issue PMM-2857. For now, if you see two different lists on ps aux outputs, the one that applies is the last one (as seen above).
Updating the list of metrics
There is currently no way to enable (or disable) metrics dynamically (however, we are working on it). We will need to stop the collector, manually get and edit the metrics list, and re-add it with the updated collectors in place. For this, we will need to know the current list of metrics used from the ps aux outputs.
Continuing with the same example, suppose we are not happy with what netdev metrics offer, and we wish to disable them to avoid unnecessary overhead. Knowing the metrics list was:
We will need to run the following commands to have it removed from the collectors list:
pmm-admin stop linux:metrics
pmm-admin rm linux:metrics
pmm-admin add linux:metrics -- -collectors.enabled=diskstats,meminfo,vmstat
Links for reference
Did you find this post useful?
You might also enjoy some of our other resources. Check out some of these recent technical webinars on using PMM, presented by my colleagues from Percona:
- Migrating to AWS Aurora, Monitoring AWS Aurora with PMM a joint webinar with the team from Autodesk
- MySQL Troubleshooting and Performance Optimization with PMM presented by our CEO, Peter Zaitsev