limit-req

Description

The limit-req Plugin limits the number of requests to your service using the leaky bucket algorithm.

Attributes

Name	Type	Required	Default	Valid values	Description
rate	integer	True		rate > 0	Threshold for number of requests per second. Requests exceeding this rate (and below burst) will be delayed to match this rate.
burst	integer	True		burst >= 0	Number of additional requests allowed to be delayed per second. If the number of requests exceeds this hard limit, they will get rejected immediately.
key_type	string	False	"var"	["var", "var_combination"]	Type of user specified key to use.
key	string	True			User specified key to base the request limiting on. If the key_type attribute is set to var, the key will be treated as a name of variable, like remote_addr or consumer_name. If the key_type is set to var_combination, the key will be a combination of variables, like $remote_addr $consumer_name. If the value of the key is empty, remote_addr will be set as the default key.
rejected_code	integer	False	503	[200,...,599]	HTTP status code returned when the requests exceeding the threshold are rejected.
rejected_msg	string	False		non-empty	Body of the response returned when the requests exceeding the threshold are rejected.
nodelay	boolean	False	false		If set to true, requests within the burst threshold would not be delayed.
allow_degradation	boolean	False	false		When set to true enables Plugin degradation when the Plugin is temporarily unavailable and allows requests to continue.

Enabling the Plugin

You can enable the Plugin on a Route as shown below:

curl http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "methods": ["GET"],
    "uri": "/index.html",
    "plugins": {
        "limit-req": {
            "rate": 1,
            "burst": 2,
            "rejected_code": 503,
            "key_type": "var",
            "key": "remote_addr"
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:9001": 1
        }
    }
}'

You can also configure the key_type to var_combination as shown:

{
    "methods": ["GET"],
    "uri": "/index.html",
    "plugins": {
        "limit-req": {
            "rate": 1,
            "burst": 2,
            "rejected_code": 503,
            "key_type": "var_combination",
            "key": "$consumer_name $remote_addr"
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:9001": 1
        }
    }
}

You can also configure the Plugin on specific consumers to limit their requests.

First, you can create a Consumer and enable the limit-req Plugin on it:

curl http://127.0.0.1:9080/apisix/admin/consumers -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "username": "consumer_jack",
    "plugins": {
        "key-auth": {
            "key": "auth-jack"
        },
        "limit-req": {
            "rate": 1,
            "burst": 3,
            "rejected_code": 403,
            "key": "consumer_name"
        }
    }
}'

In this example, the key-auth Plugin is used to authenticate the Consumer.

Next, create a Route and enable the key-auth Plugin:

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

Example usage

Once you have configured the Plugin as shown above, you can test it out. The above configuration limits to 1 request per second. If the number of requests is greater than 1 but less than 3, a delay will be added. And if the number of requests per second exceeds 3, it will be rejected.

Now if you send a request:

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

For authenticated requests:

curl -i http://127.0.0.1:9080/index.html -H 'apikey: auth-jack'

If you exceed the limit, you will receive a response with a 503 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>

You can set a custom rejected message by configuring the rejected_msg attribute. You will then receive a response like:

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."}

Disable Plugin

To disable the limit-req Plugin, you can delete the corresponding JSON configuration from the Plugin configuration. APISIX will automatically reload and you do not have to restart for this to take effect.

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

Similarly for removing the Plugin from a Consumer:

curl http://127.0.0.1:9080/apisix/admin/consumers -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "username": "consumer_jack",
    "plugins": {
        "key-auth": {
            "key": "auth-jack"
        }
    }
}'