Load Balancing

Load balancing is a technique used to distribute network request loads. It is a key consideration in designing systems that need to handle a large volume of traffic, allowing for improved system performance, scalability, and reliability

Apache APISIX supports a number of load balancing algorithms, one of which is the weighted round-robin algorithm. This algorithm distributes incoming requests over a set of servers in a cyclical pattern.

In this tutorial, you will create a route with two upstream services and uses the round-robin load balancing algorithm to load balance requests.

Prerequisite(s)

1. Complete Get APISIX to install APISIX.
2. Understand APISIX Route and Upstream.

Enable Load Balancing

Create a route with two upstream services, httpbin.org and mock.api7.ai, to distribute requests across. Both services respond with the request headers when receiving request at /headers:

curl -i "http://127.0.0.1:9180/apisix/admin/routes" -X PUT -d '
{
  "id": "getting-started-headers",
  "uri": "/headers",
  "upstream" : {
    "type": "roundrobin",
    "nodes": {
      "httpbin.org:443": 1,
      "mock.api7.ai:443": 1
    },
    "pass_host": "node",
    "scheme": "https"
  }
}'

❶ type: use roundrobin as the load balancing algorithm.

❷ nodes: upstream services.

❸ pass_host: use node to pass the host header to the upstream.

❹ scheme: use https to enable TLS with upstream.

You should receive an HTTP/1.1 201 Created response if the route was created successfully.

Validate

Generate 50 consecutive requests to APISIX /headers route to see the load-balancing effect:

resp=$(seq 50 | xargs -I{} curl "http://127.0.0.1:9080/headers" -sL) && \
  count_httpbin=$(echo "$resp" | grep "httpbin.org" | wc -l) && \
  count_mockapi7=$(echo "$resp" | grep "mock.api7.ai" | wc -l) && \
  echo httpbin.org: $count_httpbin, mock.api7.ai: $count_mockapi7

The command keeps count of the number of requests that was handled by the two services respectively. The output shows that requests were distributed over to the two services:

httpbin.org: 23, mock.api7.ai: 27

What's Next

You have learned how to configure load balancing. In the next tutorial, you will learn how to configure key authentication.