Name

resty.limit.req - Lua module for limiting request rate for OpenResty/ngx_lua.

Synopsis

# demonstrate the usage of the resty.limit.req module (alone!)
http {
    lua_shared_dict my_limit_req_store 100m;

    server {
        location / {
            access_by_lua_block {
                -- well, we could put the require() and new() calls in our own Lua
                -- modules to save overhead. here we put them below just for
                -- convenience.

                local limit_req = require "resty.limit.req"

                -- limit the requests under 200 req/sec with a burst of 100 req/sec,
                -- that is, we delay requests under 300 req/sec and above 200
                -- req/sec, and reject any requests exceeding 300 req/sec.
                local lim, err = limit_req.new("my_limit_req_store", 200, 100)
                if not lim then
                    ngx.log(ngx.ERR,
                            "failed to instantiate a resty.limit.req object: ", err)
                    return ngx.exit(500)
                end

                -- the following call must be per-request.
                -- here we use the remote (IP) address as the limiting key
                local key = ngx.var.binary_remote_addr
                local delay, err = lim:incoming(key, true)
                if not delay then
                    if err == "rejected" then
                        return ngx.exit(503)
                    end
                    ngx.log(ngx.ERR, "failed to limit req: ", err)
                    return ngx.exit(500)
                end

                if delay >= 0.001 then
                    -- the 2nd return value holds  the number of excess requests
                    -- per second for the specified key. for example, number 31
                    -- means the current request rate is at 231 req/sec for the
                    -- specified key.
                    local excess = err

                    -- the request exceeding the 200 req/sec but below 300 req/sec,
                    -- so we intentionally delay it here a bit to conform to the
                    -- 200 req/sec rate.
                    ngx.sleep(delay)
                end
            }

            # content handler goes here. if it is content_by_lua, then you can
            # merge the Lua code above in access_by_lua into your content_by_lua's
            # Lua handler to save a little bit of CPU time.
        }
    }
}

Description

This module provides APIs to help the OpenResty/ngx_lua user programmers limit request rate using the "leaky bucket" method.

If you want to use multiple different instances of this class at once or use one instance of this class with instances of other classes (like resty.limit.conn), then you must use the resty.limit.traffic module to combine them.

This Lua module's implementation is similar to NGINX's standard module ngx_limit_req. But this Lua module is more flexible in that it can be used in almost arbitrary contexts.

Files

req.md

Latest commit

History

req.md

File metadata and controls

Name

Table of Contents

Synopsis

Description

Methods

new

incoming

set_rate

set_burst

uncommit

Instance Sharing

Limiting Granularity

Installation

Community

English Mailing List

Chinese Mailing List

Bugs and Patches

Author

Copyright and License

See Also