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limit-req

Description#

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

Attributes#

NameTypeRequiredDefaultValid valuesDescription
rateintegerTruerate > 0Threshold for number of requests per second. Requests exceeding this rate (and below burst) will be delayed to match this rate.
burstintegerTrueburst >= 0Number of additional requests allowed to be delayed per second. If the number of requests exceeds this hard limit, they will get rejected immediately.
key_typestringFalse"var"["var", "var_combination"]Type of user specified key to use.
keystringTrue["remote_addr", "server_addr", "http_x_real_ip", "http_x_forwarded_for", "consumer_name"]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_codeintegerFalse503[200,...,599]HTTP status code returned when the requests exceeding the threshold are rejected.
rejected_msgstringFalsenon-emptyBody of the response returned when the requests exceeding the threshold are rejected.
nodelaybooleanFalsefalseIf set to true, requests within the burst threshold would not be delayed.
allow_degradationbooleanFalsefalseWhen set to true enables Plugin degradation when the Plugin is temporarily unavailable and allows requests to continue.
policystringFalse"local"["local", "redis", "redis-cluster"]Rate-limiting policies to use for retrieving and increment the limit count. When set to local the counters will be locally stored in memory on the node. When set to redis counters are stored on a Redis server and will be shared across the nodes. It is done usually for global speed limiting, and setting to redis-cluster uses a Redis cluster instead of a single instance.
redis_hoststringrequired when policy is redisAddress of the Redis server. Used when the policy attribute is set to redis.
redis_portintegerFalse6379[1,...]Port of the Redis server. Used when the policy attribute is set to redis.
redis_usernamestringFalseUsername for Redis authentication if Redis ACL is used (for Redis version >= 6.0). If you use the legacy authentication method requirepass to configure Redis password, configure only the redis_password. Used when the policy is set to redis.
redis_passwordstringFalsePassword for Redis authentication. Used when the policy is set to redis or redis-cluster.
redis_sslbooleanFalsefalseIf set to true, then uses SSL to connect to redis instance. Used when the policy attribute is set to redis.
redis_ssl_verifybooleanFalsefalseIf set to true, then verifies the validity of the server SSL certificate. Used when the policy attribute is set to redis. See tcpsock:sslhandshake.
redis_databaseintegerFalse0redis_database >= 0Selected database of the Redis server (for single instance operation or when using Redis cloud with a single entrypoint). Used when the policy attribute is set to redis.
redis_timeoutintegerFalse1000[1,...]Timeout in milliseconds for any command submitted to the Redis server. Used when the policy attribute is set to redis or redis-cluster.
redis_cluster_nodesarrayrequired when policy is redis-clusterAddresses of Redis cluster nodes. Used when the policy attribute is set to redis-cluster.
redis_cluster_namestringrequired when policy is redis-clusterName of the Redis cluster service nodes. Used when the policy attribute is set to redis-cluster.
redis_cluster_sslbooleanFalsefalseIf set to true, then uses SSL to connect to redis-cluster. Used when the policy attribute is set to redis-cluster.
redis_cluster_ssl_verifybooleanFalsefalseIf set to true, then verifies the validity of the server SSL certificate. Used when the policy attribute is set to redis-cluster.

Enable Plugin#

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

curl http://127.0.0.1:9180/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://127.0.0.1:9180/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://127.0.0.1:9180/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."}

Delete Plugin#

To remove 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://127.0.0.1:9180/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://127.0.0.1:9180/apisix/admin/consumers -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
"username": "consumer_jack",
"plugins": {
"key-auth": {
"key": "auth-jack"
}
}
}'