To change the capacity for a certain cache class, make a POST request to /actuator/cache/<cacheClass> with a JSON body that specifies the capacity for the cache class, as shown in the following example:

curl -X POST -H "Content-Type: application/json" \
     -d '{"capacity": 20000}' \
     http://localhost:8081/actuator/cache/java.lang.Object

The response includes a message about the performed change, and the new state of the cache class:

Response. 

{
  "message": "Capacity changed for cache class 'java.lang.Object': 10000 -> 20000",
  "result": {
    "capacity": 20000,
    "level": 107
  }
}

Note, that setting a smaller capacity for a cache class does not necessarily lead to an immediate eviction of cached values. If you want to reduce the current cache level with a reduced capacity, you can either make a separate request to trigger an eviction as described in Section 4.10.3.6, “Trigger Cache Eviction” or make a POST request with a JSON body to set both a new capacity and trigger an eviction:

curl -X POST -H "Content-Type: application/json" \
     -d '{"capacity": 100, "evict": true}' \
     http://localhost:8081/actuator/cache/java.lang.Object

The response includes a message about the performed changes, and the new state of the cache class:

Response. 

{
  "message": "Capacity changed for cache class 'java.lang.Object': 20000 -> 100; Cache eviction triggered for cache class: 'java.lang.Object'.",
  "result": {
    "capacity": 100,
    "level": 90
  }
}