Configuring Rate Limiting for an API Gateway Cluster¶
Typically, you need to have more than one Gateway node in your WSO2 API Manager (WSO2 API-M) deployment when either having an all-in-one set up in a high availability (HA) deployment (i.e., 2 nodes) or when having a distributed set up with multiple Gateways. In such scenarios, for features such as burst control and backend rate limiting to work properly, it requires maintaining distributed request counters across all gateway nodes.
WSO2 API-M supports the facility to maintain these counters in a distributed Redis cluster. You can simply connect API-M to a Redis cluster, and then the API-M Gateway nodes will take care of keeping distributed counters in it.
If you are unable to use a Redis cluster in your deployment, the fallback option is to have node-local counters. For that, you have to define rate limit policies based on the number of gateway nodes that are in the cluster. For example, if you have 3 gateway nodes, and you want to have a rate-limiting policy with 300req/s, you have to create a policy that only allows 100req/s. Then each node will allow 100req/s and in total, you will get 300req/s assuming the requests are distributed equally across all nodes. However, this option has its own limitations and is hence not an ideal solution.
Configuring a Redis cluster with API Manager¶
Follow the instructions below to configure a Redis cluster with API Manager:
Step 1 - Setup and start the Redis server¶
Refer to the official Redis documentation to set up and start the Redis server.
Step 2 - Configure the Redis server with WSO2 API-M¶
Follow the instructions below to configure the Redis server with WSO2 API Manager.
<API-M_HOME>/repository/conf/deployment.tomlfile of the Gateway node.
Add the following configurations to the
[apim.redis_config] host = "<Redis-host>" port = "<Redis-port>" user = "<Redis-username>" password = "<Redis-password>" [throttle_properties] 'throttling.distributed.counter.type' = "redis"
Step 3 - Start the WSO2 API-M server¶
For more information, see Running the API Manager Runtime.Top