A replica metric can be the memory usage

[mtneug]

Description

The memory usage is a general metric that is provided by Docker for each replica. It might not fully capture the state of a replica, but it can always be used even for applications that expose no other information. In spate the memory usage is a relative value between 0 and 1. It is also a metric type with a default value of 0.8. Users can only declare on memory usage metric per service.

Design

The replica metric memory usage is also its own metric type called memory. Using it only requires that the label de.mtneug.spate.metrics.<key>.type=memory is present. This metric type can only be used once. Using it multiple times results in a deactivation of autoscaling and an error logs message. The default target value of 0.8 can be overwritten.

Example

$ docker service create \
   --name service \
   --label de.mtneug.spate.metrics.memory.type=memory \
   --label de.mtneug.spate.metrics.memory.target=0.7 \
   ...
   my/service