nginx lua集成kafka的实现方法

下面我将为你详细讲解“nginx lua集成kafka的实现方法”的完整攻略。

准备工作

• 安装Openresty
• 安装kafka

代码实现

安装kafka-lua

kafka-lua具体安装步骤可参考Github官网：kafka-lua。

lua代码基本骨架

local producers = require ("resty.kafka.producers")
local cjson = require ("cjson")

local broker_list= {
    { host = "127.0.0.1", port = 9092 },
    { host = "127.0.0.1", port = 9093 },
    { host = "127.0.0.1", port = 9094 }
}

local key = "logkey"
local tmpkey,err = ngx.var.arg_key

if tmpkey and tmpkey ~= ngx.null then
    key = tmpkey
end

local message = ngx.var.arg_message

if not message or message == ngx.null then
    ngx.exit(ngx.HTTP_BAD_REQUEST)
end

实现发送消息到kafka

local producer = assert(producers:new(broker_list))

local message = {
    key = key,
    value = message,
}

local data,err = cjson.encode(message)

if not data then
    ngx.log(ngx.ERR, "failed to encode data: ", err)
    return
end

ok, err = producer:send("log_t", key, data)

if not ok then
    ngx.log(ngx.ERR, "failed to send log: ", err)
    return
end

完整实例

下面是一个完整的nginx lua集成kafka的示例：

http {
    init_by_lua_block {
        local producers = require ("resty.kafka.producers")
        local cjson = require ("cjson")

        local broker_list= {
            { host = "127.0.0.1", port = 9092 },
            { host = "127.0.0.1", port = 9093 },
            { host = "127.0.0.1", port = 9094 }
        }

        local key = "logkey"
        local tmpkey,err = ngx.var.arg_key

        if tmpkey and tmpkey ~= ngx.null then
            key = tmpkey
        end

        local message = ngx.var.arg_message

        if not message or message == ngx.null then
            ngx.exit(ngx.HTTP_BAD_REQUEST)
        end

        local producer = assert(producers:new(broker_list))

        local message = {
            key = key,
            value = message,
        }

        local data,err = cjson.encode(message)

        if not data then
            ngx.log(ngx.ERR, "failed to encode data: ", err)
            return
        end

        ok, err = producer:send("log_t", key, data)

        if not ok then
            ngx.log(ngx.ERR, "failed to send log: ", err)
            return
        end
    }
}

示例一

下面介绍一个简单的kafka生产者程序，它使用lua-resty-kafka发送消息到kafka中。

local producer = require "resty.kafka.producer"
local broker_list = { { host = "127.0.0.1", port = 9092 } }
local key = "testkey"
local message = "hello kafka"
local topic = "test_topic"

local p = producer:new(broker_list)

local ok, err = p:send(topic, key, message)

if not ok then
    ngx.log(ngx.ERR, "failed to send log: ", err)
    return
end

示例中，我们首先引入了resty.kafka.producer模块，接着基于连接信息初始化producer实例对象，并通过producer:send发送消息至kafka中，其中需要指定消息的key和value，以及消息所属的topic。

示例二

下面介绍一个lua-resty-kafka的消费者程序。示例中指定消费的topic为test_topic，随后从该topic中读取消息内容，输出给nginx日志。

local consumer = require "resty.kafka.consumer"
local broker_list = { { host = "127.0.0.1", port = 9092 } }
local topic = "test_topic"
local partition = 0
local consumer_id = ngx.worker.pid()
local client = consumer:new(broker_list, consumer_id, {auto_commit = true})
local offset, err = client:offset(topic, partition, "latest")

if not offset then
    ngx.log(ngx.ERR, "offset failed: ", err)
    return
end

local partition_client = client:get_partition(topic, partition, offset)

while true do
    local message, err = partition_client:recv()

    if not message then
        ngx.log(ngx.ERR, "recv err:", err)
        return
    end

    if message ~= nil then
        ngx.log(ngx.INFO, message.offset, ":", message.key, ":", message.value)
    end
end

总结

以上是一个完整的nginx lua集成kafka的实现攻略，包括了安装Openresty和kafka，以及lua的代码实现部分。此外，也提供了两个示例程序来帮助理解相关内容。希望可以对你有所帮助。