Kong插件快速开发

详细的开发文档：https://docs.konghq.com/2.0.x/plugin-development/

一、背景

今天我们来快速开发一个kong插件，插件的功能是客户端可以传递一个lambda函数，在Kong网关中运行，运行结果会以Header头的形式返回到客户端。

大家可以通过这个插件，来快速的体验PDK提供的函数接口。

二、安装Kong

CentOS系统可以使用下面的命令来完成安装

sudo yum install -y wget
wget https://bintray.com/kong/kong-rpm/rpm -O bintray-kong-kong-rpm.repo
export major_version=`grep -oE '[0-9]+\.[0-9]+' /etc/redhat-release | cut -d "." -f1`
sed -i -e 's/baseurl.*/&\/centos\/'$major_version''/ bintray-kong-kong-rpm.repo
sudo mv bintray-kong-kong-rpm.repo /etc/yum.repos.d/
sudo yum install -y kong

三 启动Kong

1. 创建配置文件

cp /etc/kong/kong.conf.default /etc/kong/kong.conf

2. 修改配置文件/etc/kong/kong.conf

sed -i "/^#database/i\database = off" /etc/kong/kong.conf

3. 启动kong

kong start

4. 查看默认配置

如果访问成功，代表kong已经成功运行

curl http://127.0.0.1:8001/config

四、开发插件

1. 进入到kong的插件目录/usr/local/share/lua/5.1/kong/plugins，创建两个lua文件

cd /usr/local/share/lua/5.1/kong/plugins
mkdir debug
cd debug

cat > schema.lua <<EOF
local typedefs = require "kong.db.schema.typedefs"


return {
  name = "debug",
  fields = {
    { protocols = typedefs.protocols_http },
    { config = {
        type = "record",
        fields = {
          { lambda_name = { type = "string", default = "X-Kong-Lambda" }, },
          { result_name = { type = "string", default = "X-Kong-Result" }, },
        },
      },
    },
  },
}
EOF

cat > handler.lua <<EOF
local cjson = require("cjson.safe").new()

local DebugHandler = {}

DebugHandler.PRIORITY = 6
DebugHandler.VERSION = "2.0.0"


function DebugHandler:header_filter(conf)
  local lambda = kong.request.get_header(conf.lambda_name)
  if lambda then
    local result = cjson.encode(loadstring(lambda)())
    kong.response.set_header(conf.result_name, result)
  end
end
EOF

cd

2. 自动加载插件，修改配置文件/etc/kong/kong.conf

sed -i "/^#plugins/i\plugins = bundled,debug" /etc/kong/kong.conf

3. 重新启动kong

kong restart

4. 修改apis.yaml,配置插件

cd

cat > apis.yml <<EOF
_format_version: "1.1"
services:
 - name: httpbin-service
   url: http://httpbin.org/
   # Entities can store tags as metadata
   tags:
   - httpbin
   # Entities that have a foreign-key relationship can be nested:
   routes:
   - name: httpbin-route
     paths:
     - /
   plugins:
   - name: debug
     config:
       lambda_name: X-Kong-Lambda
       result_name: X-Kong-Result
EOF

5. 检测配置文件是否合法

kong config parse apis.yml

6. 上传配置文件

curl http://127.0.0.1:8001/config -F "config=@apis.yml"

7. 测试接口

# curl -v \
-H "X-Kong-Lambda: return kong.router.get_service().name" \
http://127.0.0.1:8000/ip

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