v2.5.6 - Experimental Akka Cluster Metrics
Akka Cluster Metrics
This release comes with experimental support for a bunch of Akka Cluster-related metrics! We can break down the metrics into per-state member counts that help you get a general view of the cluster status, and per-member status counts, which let you see exactly which nodes are on each state.
Per-state Member Counts
These metrics track how many cluster members are on each of the possible states in the cluster. The metric names for these states are:
- akka.cluster.members.joining.count
- akka.cluster.members.weakly-up.count
- akka.cluster.members.up.count
- akka.cluster.members.leaving.count
- akka.cluster.members.exiting.count
- akka.cluster.members.down.count
- akka.cluster.members.removed.count
- akka.cluster.members.total.count
All members of the cluster expose these metrics with the number of members they see in each state. Since these metrics are exposed as gauges, you could always make a chart of the max(akka.cluster.members.[state].count) to see how many members are on a given state. For example, for members in the Up state you can see how a cluster starts growing in members:
Per-member Status Counts
The metrics we mentioned above will help you know, for example, that there are 3 members in the Joining state, but what if you want to know whichare those members? That's what the per-member metrics are for. These metrics have a member tag that identifies the member being measured, and the value of the metric tells you the state it is currently in. Here is a breakdown of the possible values:
akka.cluster.member.status
- Joining = 1
- WeaklyUp = 2
- Up = 3
- Leaving = 4
- Exiting = 5
- Down = 6
- Removed = 7
akka.cluster.member.reachability
- Reachable = 0
- Unreachable = 1
The same as with the status metrics, you can plot the max(akka.cluster.members.status) and see what's the latest on each member of the cluster! In the example below, all members are on state 3 (Up):
Enabling Cluster Metrics
This feature isn't fully tested yet so we are not enabling it by default. To enable Akka Cluster Metrics, add this setting to your application.conf file:
kamon.instrumentation.akka.cluster.track-cluster-metrics=yes
