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limit-count
Apache APISIX
API Gateway
Limit Count
This document contains information about the Apache APISIX limit-count Plugin, you can use it to limit the number of requests to your service by a given count per time.

Description

The limit-count Plugin limits the number of requests to your service by a given count per time. The plugin is using Fixed Window algorithm.

Attributes

Name Type Required Default Valid values Description
count integer True count > 0 Maximum number of requests to allow.
time_window integer True time_window > 0 Time in seconds before count is reset.
key_type string False "var" ["var", "var_combination", "constant"] Type of user specified key to use.
key string False "remote_addr" User specified key to base the request limiting on. If the key_type attribute is set to constant, the key will be treated as a constant value. 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.
policy string False "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.
allow_degradation boolean False false When set to true enables Plugin degradation when the Plugin is temporarily unavailable (for example, a Redis timeout) and allows requests to continue.
show_limit_quota_header boolean False true When set to true, adds X-RateLimit-Limit (total number of requests) and X-RateLimit-Remaining (remaining number of requests) to the response header.
group string False non-empty Group to share the counter with. Routes configured with the same group will share the same counter. Do not configure with a value that was previously used in this attribute before as the plugin would not allow.
redis_host string required when policy is redis Address of the Redis server. Used when the policy attribute is set to redis.
redis_port integer False 6379 [1,...] Port of the Redis server. Used when the policy attribute is set to redis.
redis_username string False Username 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_password string False Password for Redis authentication. Used when the policy is set to redis or redis-cluster.
redis_ssl boolean False false If set to true, then uses SSL to connect to redis instance. Used when the policy attribute is set to redis.
redis_ssl_verify boolean False false If 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_database integer False 0 redis_database >= 0 Selected 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_timeout integer False 1000 [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_nodes array required when policy is redis-cluster Addresses of Redis cluster nodes. Used when the policy attribute is set to redis-cluster.
redis_cluster_name string required when policy is redis-cluster Name of the Redis cluster service nodes. Used when the policy attribute is set to redis-cluster.
redis_cluster_ssl boolean False false If set to true, then uses SSL to connect to redis-cluster. Used when the policy attribute is set to redis-cluster.
redis_cluster_ssl_verify boolean False false If 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:

:::note You can fetch the admin_key from config.yaml and save to an environment variable with the following command:

admin_key=$(yq '.deployment.admin.admin_key[0].key' conf/config.yaml | sed 's/"//g')

:::

curl -i http://127.0.0.1:9180/apisix/admin/routes/1 \
-H "X-API-KEY: $admin_key" -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
        }
    }
}'

You can also configure the key_type to var_combination as shown:

curl -i http://127.0.0.1:9180/apisix/admin/routes/1 \
-H "X-API-KEY: $admin_key" -X PUT -d '
{
    "uri": "/index.html",
    "plugins": {
        "limit-count": {
            "count": 2,
            "time_window": 60,
            "rejected_code": 503,
            "key_type": "var_combination",
            "key": "$consumer_name $remote_addr"
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:9001": 1
        }
    }
}'

You can also create a group to share the same counter across multiple Routes:

curl -i http://127.0.0.1:9180/apisix/admin/services/1 \
-H "X-API-KEY: $admin_key" -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
        }
    }
}'

Now every Route which belongs to group services_1#1640140620 (or the service with ID 1) will share the same counter.

curl -i http://127.0.0.1:9180/apisix/admin/routes/1 \
-H "X-API-KEY: $admin_key" -X PUT -d '
{
    "service_id": "1",
    "uri": "/hello"
}'
curl -i http://127.0.0.1:9180/apisix/admin/routes/2 \
-H "X-API-KEY: $admin_key" -X PUT -d '
{
    "service_id": "1",
    "uri": "/hello2"
}'
curl -i http://127.0.0.1:9080/hello
HTTP/1.1 200 ...

You can also share the same limit counter for all your requests by setting the key_type to constant:

curl -i http://127.0.0.1:9180/apisix/admin/services/1 \
-H "X-API-KEY: $admin_key" -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
        }
    }
}'

The above configuration means that when the group attribute of the limit-count plugin is configured to services_1#1640140620 for multiple routes, requests to those routes will share the same counter, even if the requests come from different IP addresses.

:::note

The configuration of limit-count in the same group must be consistent. If you want to change the configuration, you need to update the value of the corresponding group at the same time.

:::

For cluster-level traffic limiting, you can use a Redis server. The counter will be shared between different APISIX nodes to achieve traffic limiting.

The example below shows how you can use the redis policy:

curl -i http://127.0.0.1:9180/apisix/admin/routes/1 \
-H "X-API-KEY: $admin_key" -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
        }
    }
}'

Similarly you can also configure the redis-cluster policy:

curl -i http://127.0.0.1:9180/apisix/admin/routes/1 \
-H "X-API-KEY: $admin_key" -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
        }
    }
}'

In addition, you can use APISIX secret to store and reference plugin attributes. APISIX currently supports storing secrets in two ways - Environment Variables and HashiCorp Vault. For example, in case you have environment variables REDIS_HOST and REDIS_PASSWORD set, you can use them in the plugin configuration as shown below:

curl -i http://127.0.0.1:9180/apisix/admin/routes/1 \
-H "X-API-KEY: $admin_key" -X PUT -d '
{
    "uri": "/index.html",
    "plugins": {
        "limit-count": {
            "count": 2,
            "time_window": 60,
            "rejected_code": 503,
            "key": "remote_addr",
            "policy": "redis",
            "redis_host": "$ENV://REDIS_HOST",
            "redis_port": 6379,
            "redis_password": "$ENV://REDIS_PASSWORD",
            "redis_database": 1,
            "redis_timeout": 1001
        }
    },
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:1980": 1
        }
    }
}'

Example usage

The above configuration limits to 2 requests in 60 seconds. The first two requests will work and the response headers will contain the headers X-RateLimit-Limit and X-RateLimit-Remaining and X-RateLimit-Reset, represents the total number of requests that are limited, the number of requests that can still be sent, and the number of seconds left for the counter to reset:

curl -i http://127.0.0.1:9080/index.html
HTTP/1.1 200 OK
Content-Type: text/html
Content-Length: 13175
Connection: keep-alive
X-RateLimit-Limit: 2
X-RateLimit-Remaining: 0
X-RateLimit-Reset: 58
Server: APISIX web server

When you visit for a third time in the 60 seconds, you will receive a response with 503 code. Currently, in the case of rejection, the limit count headers is also returned:

HTTP/1.1 503 Service Temporarily Unavailable
Content-Type: text/html
Content-Length: 194
Connection: keep-alive
X-RateLimit-Limit: 2
X-RateLimit-Remaining: 0
X-RateLimit-Reset: 58
Server: APISIX web server

You can also set a custom response by configuring the rejected_msg attribute:

HTTP/1.1 503 Service Temporarily Unavailable
Content-Type: text/html
Content-Length: 194
Connection: keep-alive
X-RateLimit-Limit: 2
X-RateLimit-Remaining: 0
X-RateLimit-Reset: 58
Server: APISIX web server

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

Customize Rate Limiting Headers

The following example demonstrates how you can use plugin metadata to customize the rate limiting response header names, which are by default X-RateLimit-Limit, X-RateLimit-Remaining, and X-RateLimit-Reset.

Configure the plugin metadata for this plugin and update the headers:

curl "http://127.0.0.1:9180/apisix/admin/plugin_metadata/limit-count" -X PUT -d '
{
  "log_format": {
    "limit_header": "X-Custom-RateLimit-Limit",
    "remaining_header": "X-Custom-RateLimit-Remaining",
    "reset_header": "X-Custom-RateLimit-Reset"
  }
}'

Create a route with limit-count plugin that allows for a quota of 1 within a 30-second window per remote address:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${ADMIN_API_KEY}" \
  -d '{
    "id": "limit-count-route",
    "uri": "/get",
    "plugins": {
      "limit-count": {
        "count": 1,
        "time_window": 30,
        "rejected_code": 429,
        "key_type": "var",
        "key": "remote_addr",
        "window_type": "sliding"
      }
      # highlight-end
    },
    "upstream": {
      "type": "roundrobin",
      "nodes": {
        "httpbin.org:80": 1
      }
    }
  }'

Send a request to verify:

curl -i "http://127.0.0.1:9080/get"

You should receive an HTTP/1.1 200 OK response and see the following headers:

X-Custom-RateLimit-Limit: 1
X-Custom-RateLimit-Remaining: 0
X-Custom-RateLimit-Reset: 28

Delete Plugin

To remove the limit-count 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: $admin_key" -X PUT -d '
{
    "methods": ["GET"],
    "uri": "/index.html",
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "127.0.0.1:1980": 1
        }
    }
}'