a6-plugin-limit-count

Overview

The limit-count plugin rate-limits requests using a fixed-window counter algorithm. Define a maximum number of requests (count) within a time interval (time_window). Supports per-IP, per-consumer, per-header, or custom variable keys. For distributed APISIX deployments, use Redis or Redis-cluster as the shared counter backend.

When to Use

• Simple request counting (e.g., 100 requests per hour)
• API quota enforcement per consumer or API key
• Shared rate limits across multiple APISIX nodes (via Redis)
• Grouped quotas across multiple routes

Plugin Configuration Reference

Core Fields

Field	Type	Required	Default	Description
count	integer	Yes*	—	Max requests allowed in the time window. > 0
time_window	integer	Yes*	—	Time window in seconds. > 0
key_type	string	No	"var"	Key type: "var", "var_combination", or "constant"
key	string	No	"remote_addr"	Variable name or combination for counting
rejected_code	integer	No	503	HTTP status on rejection (200–599)
rejected_msg	string	No	—	Custom rejection message body
group	string	No	—	Share counters across routes with same group ID
policy	string	No	"local"	Storage: "local", "redis", or "redis-cluster"
show_limit_quota_header	boolean	No	true	Include X-RateLimit-* headers in responses
allow_degradation	boolean	No	false	Allow requests when plugin fails

*Required unless using rules array.

Redis Fields (when policy: "redis")

Field	Type	Required	Default	Description
redis_host	string	Yes	—	Redis server address
redis_port	integer	No	6379	Redis port
redis_username	string	No	—	Redis ACL username
redis_password	string	No	—	Redis password
redis_database	integer	No	0	Redis database index
redis_timeout	integer	No	1000	Timeout in milliseconds
redis_ssl	boolean	No	false	Enable TLS to Redis

Redis Cluster Fields (when policy: "redis-cluster")

Field	Type	Required	Default	Description
redis_cluster_nodes	array[string]	Yes	—	Array of "host:port" (min 2)
redis_cluster_name	string	Yes	—	Cluster name
redis_password	string	No	—	Cluster password
redis_timeout	integer	No	1000	Timeout in milliseconds
redis_cluster_ssl	boolean	No	false	Enable TLS

Key Types

key_type	key Format	Example	Description
"var"	NGINX variable (no $)	"remote_addr"	Single variable
"var_combination"	$var1 $var2	"$remote_addr $consumer_name"	Multiple variables combined
"constant"	Any string	"global"	Same counter for all requests

Response Headers

When show_limit_quota_header: true (default):

Header	Description
X-RateLimit-Limit	Total quota for the time window
X-RateLimit-Remaining	Remaining requests in current window
X-RateLimit-Reset	Seconds until counter resets

Step-by-Step: Basic Rate Limiting

1. Rate limit by client IP (route-level)

a6 route create -f - <<'EOF'
{
  "id": "rate-limited-api",
  "uri": "/api/*",
  "plugins": {
    "limit-count": {
      "count": 100,
      "time_window": 60,
      "key_type": "var",
      "key": "remote_addr",
      "rejected_code": 429,
      "rejected_msg": "Rate limit exceeded. Try again later."
    }
  },
  "upstream": {
    "type": "roundrobin",
    "nodes": {
      "backend:8080": 1
    }
  }
}
EOF

100 requests per 60 seconds per client IP.

2. Rate limit per consumer

a6 consumer create -f - <<'EOF'
{
  "username": "free-tier",
  "plugins": {
    "limit-count": {
      "count": 100,
      "time_window": 3600,
      "rejected_code": 429
    }
  }
}
EOF

a6 consumer create -f - <<'EOF'
{
  "username": "premium",
  "plugins": {
    "limit-count": {
      "count": 10000,
      "time_window": 3600,
      "rejected_code": 429
    }
  }
}
EOF

Consumer-level limits apply across all routes the consumer accesses.

Common Patterns

Shared quota across routes (group)

{
  "plugins": {
    "limit-count": {
      "count": 1000,
      "time_window": 3600,
      "group": "api-v1",
      "rejected_code": 429
    }
  }
}

All routes with "group": "api-v1" share the same 1000 req/hour counter. Important: All routes in a group must have identical limit-count config.

Multi-variable key (IP + consumer)

{
  "plugins": {
    "limit-count": {
      "count": 50,
      "time_window": 60,
      "key_type": "var_combination",
      "key": "$remote_addr $consumer_name",
      "rejected_code": 429
    }
  }
}

Global rate limit (all requests share one counter)

{
  "plugins": {
    "limit-count": {
      "count": 10000,
      "time_window": 60,
      "key_type": "constant",
      "key": "global",
      "rejected_code": 429
    }
  }
}

Distributed rate limiting with Redis

{
  "plugins": {
    "limit-count": {
      "count": 1000,
      "time_window": 60,
      "key": "remote_addr",
      "policy": "redis",
      "redis_host": "redis.example.com",
      "redis_port": 6379,
      "redis_password": "secret",
      "redis_database": 0,
      "redis_ssl": true,
      "rejected_code": 429
    }
  }
}

Use Redis when running multiple APISIX nodes to share counters.

Redis cluster

{
  "plugins": {
    "limit-count": {
      "count": 1000,
      "time_window": 60,
      "key": "remote_addr",
      "policy": "redis-cluster",
      "redis_cluster_nodes": [
        "192.168.1.10:6379",
        "192.168.1.11:6379",
        "192.168.1.12:6379"
      ],
      "redis_cluster_name": "apisix-cluster",
      "redis_password": "secret",
      "rejected_code": 429
    }
  }
}

Troubleshooting

Symptom	Cause	Fix
Limits not shared across APISIX nodes	Using policy: "local" (default)	Switch to "redis" or "redis-cluster"
Group config rejected	Mismatched configs in same group	Ensure all routes in group have identical limit-count config
Unexpected counter reset	Fixed-window boundary	Normal behavior — counters reset at fixed intervals
Key empty, all clients share one counter	Variable doesn't exist	Verify key variable name; falls back to remote_addr
Rate limit headers missing	show_limit_quota_header: false	Set to true (default)
503 instead of 429	Default rejected_code is 503	Set rejected_code: 429 explicitly

Fixed-Window Algorithm Note

limit-count uses a fixed-window algorithm. Counters reset at exact intervals. This means a burst at the boundary of two windows can temporarily exceed the intended rate (e.g., 100 req/min allows 200 requests if 100 come at t=59s and 100 at t=61s). For smoother rate limiting, combine with limit-req (leaky bucket).

Config Sync Example

version: "1"
consumers:
  - username: free-tier
    plugins:
      limit-count:
        count: 100
        time_window: 3600
        rejected_code: 429
routes:
  - id: rate-limited-api
    uri: /api/*
    plugins:
      limit-count:
        count: 1000
        time_window: 60
        key: remote_addr
        rejected_code: 429
    upstream_id: api-upstream
upstreams:
  - id: api-upstream
    type: roundrobin
    nodes:
      "backend:8080": 1