limit-count.md

title
limit-count

Description

Limit request rate by a fixed number of requests in a given time window.

Attributes

Name	Type	Requirement	Default	Valid	Description
count	integer	required		count > 0	the specified number of requests threshold.
time_window	integer	required		time_window > 0	the time window in seconds before the request count is reset.
key_type	string	optional	"var"	["var", "var_combination", "constant"]	the type of key.
key	string	optional	"remote_addr"		the user specified key to limit the rate. If the key_type is "constant", the key will be treated as a constant. If the key_type is "var", the key will be treated as a name of variable. If the key_type is "var_combination", the key will be a combination of variables. For example, if we use "$remote_addr $consumer_name" as key, plugin will be restricted by two variables which are "remote_addr" and "consumer_name". If the value of the key is empty, remote_addr will be set as the default key.
rejected_code	integer	optional	503	[200,...,599]	The HTTP status code returned when the request exceeds the threshold is rejected, default 503.
rejected_msg	string	optional		non-empty	The response body returned when the request exceeds the threshold is rejected.
policy	string	optional	"local"	["local", "redis", "redis-cluster"]	The rate-limiting policies to use for retrieving and incrementing the limits. Available values are local(the counters will be stored locally in-memory on the node), redis(counters are stored on a Redis server and will be shared across the nodes, usually use it to do the global speed limit), and redis-cluster which works the same as redis but with redis cluster.
allow_degradation	boolean	optional	false		Whether to enable plugin degradation when the limit-count function is temporarily unavailable(e.g. redis timeout). Allow requests to continue when the value is set to true, default false.
show_limit_quota_header	boolean	optional	true		Whether show X-RateLimit-Limit and X-RateLimit-Remaining (which mean the total number of requests and the remaining number of requests that can be sent) in the response header, default true.
group	string	optional		non-empty	Route configured with the same group will share the same counter
redis_host	string	required for redis			When using the redis policy, this property specifies the address of the Redis server.
redis_port	integer	optional	6379	[1,...]	When using the redis policy, this property specifies the port of the Redis server.
redis_password	string	optional			When using the redis or redis-cluster policy, this property specifies the password of the Redis server.
redis_database	integer	optional	0	redis_database >= 0	When using the redis policy, this property specifies the database you selected of the Redis server, and only for non Redis cluster mode (single instance mode or Redis public cloud service that provides single entry).
redis_timeout	integer	optional	1000	[1,...]	When using the redis or redis-cluster policy, this property specifies the timeout in milliseconds of any command submitted to the Redis server.
redis_cluster_nodes	array	required when policy is redis-cluster			When using redis-cluster policy，This property is a list of addresses of Redis cluster service nodes (at least two).
redis_cluster_name	string	required when policy is redis-cluster			When using redis-cluster policy, this property is the name of Redis cluster service nodes.

How To Enable

Here's an example, enable the limit count plugin on the specified route when setting key_type to var :

curl -i http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "uri": "/index.html",
    "plugins": {
        "limit-count": {
            "count": 2,
            "time_window": 60,
            "rejected_code": 503,
            "key_type": "var",
            "key": "remote_addr"
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:9001": 1
        }
    }
}'

Here's an example, enable the limit count plugin on the specified route when setting key_type to var_combination :

curl -i http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "uri": "/index.html",
    "plugins": {
        "limit-count": {
            "count": 2,
            "time_window": 60,
            "rejected_code": 503,
            "key_type": "var_combination",
            "key": "$consumer_name $remote_addr"
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:9001": 1
        }
    }
}'

You also can complete the above operation through the web interface, first add a route, then add limit-count plugin:

It is possible to share the same limit counter across different routes. For example,

curl -i http://127.0.0.1:9080/apisix/admin/services/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "plugins": {
        "limit-count": {
            "count": 1,
            "time_window": 60,
            "rejected_code": 503,
            "key": "remote_addr",
            "group": "services_1#1640140620"
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:1980": 1
        }
    }
}'

Every route which group name is "services_1#1640140620" will share the same count limitation 1 in one minute per remote_addr.

$ curl -i http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "service_id": "1",
    "uri": "/hello"
}'

$ curl -i http://127.0.0.1:9080/apisix/admin/routes/2 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "service_id": "1",
    "uri": "/hello2"
}'

$ curl -i http://127.0.0.1:9080/hello
HTTP/1.1 200 ...

$ curl -i http://127.0.0.1:9080/hello2
HTTP/1.1 503 ...

Note that every limit-count configuration of the same group must be the same. Therefore, once update the configuration, we also need to update the group name.

It is also possible to share the same limit counter in all requests. For example,

curl -i http://127.0.0.1:9080/apisix/admin/services/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "plugins": {
        "limit-count": {
            "count": 1,
            "time_window": 60,
            "rejected_code": 503,
            "key": "remote_addr",
            "key_type": "constant",
            "group": "services_1#1640140621"
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:1980": 1
        }
    }
}'

Compared with the previous configuration, we set the key_type to constant. By setting key_type to constant, we don't evaluate the value of key but treat it as a constant.

Now every route which group name is "services_1#1640140621" will share the same count limitation 1 in one minute among all the requests, even these requests are from different remote_addr.

If you need a cluster-level precision traffic limit, then we can do it with the redis server. The rate limit of the traffic will be shared between different APISIX nodes to limit the rate of cluster traffic.

Here is the example if we use single redis policy:

curl -i http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "uri": "/index.html",
    "plugins": {
        "limit-count": {
            "count": 2,
            "time_window": 60,
            "rejected_code": 503,
            "key": "remote_addr",
            "policy": "redis",
            "redis_host": "127.0.0.1",
            "redis_port": 6379,
            "redis_password": "password",
            "redis_database": 1,
            "redis_timeout": 1001
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:1980": 1
        }
    }
}'

If using redis-cluster policy:

curl -i http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "uri": "/index.html",
    "plugins": {
        "limit-count": {
            "count": 2,
            "time_window": 60,
            "rejected_code": 503,
            "key": "remote_addr",
            "policy": "redis-cluster",
            "redis_cluster_nodes": [
              "127.0.0.1:5000",
              "127.0.0.1:5001"
            ],
            "redis_password": "password",
            "redis_cluster_name": "redis-cluster-1"
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:1980": 1
        }
    }
}'

Test Plugin

The above configuration limits access to only 2 times in 60 seconds. The first two visits will be normally:

curl -i http://127.0.0.1:9080/index.html

The response header contains X-RateLimit-Limit and X-RateLimit-Remaining, which mean the total number of requests and the remaining number of requests that can be sent:

HTTP/1.1 200 OK
Content-Type: text/html
Content-Length: 13175
Connection: keep-alive
X-RateLimit-Limit: 2
X-RateLimit-Remaining: 0
Server: APISIX web server

When you visit for the third time, you will receive a response with the 503 HTTP code:

HTTP/1.1 503 Service Temporarily Unavailable
Content-Type: text/html
Content-Length: 194
Connection: keep-alive
Server: APISIX web server

<html>
<head><title>503 Service Temporarily Unavailable</title></head>
<body>
<center><h1>503 Service Temporarily Unavailable</h1></center>
<hr><center>openresty</center>
</body>
</html>

At the same time, if you set the property rejected_msg to "Requests are too frequent, please try again later." , when you visit for the third time, you will receive a response body like below:

HTTP/1.1 503 Service Temporarily Unavailable
Content-Type: text/html
Content-Length: 194
Connection: keep-alive
Server: APISIX web server

{"error_msg":"Requests are too frequent, please try again later."}

This means that the limit count plugin is in effect.

Disable Plugin

When you want to disable the limit count plugin, it is very simple, you can delete the corresponding json configuration in the plugin configuration, no need to restart the service, it will take effect immediately:

curl http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "methods": ["GET"],
    "uri": "/index.html",
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:1980": 1
        }
    }
}'

The limit count plugin has been disabled now. It works for other plugins.