Openresty implements http access request

         If this is the first time you read this article, you can read this introductory article about openresty first: Overview of Openresty

        There may be a need to access other services in openresty. We needed to regularly go to another service to pull some configuration information, and then change the configuration. Implementing this function requires the following steps:

• Write lua script files to implement http requests
• Add dependent library source files to the lualib directory
• Copy the lua code file to the path
• Modify the nginx.conf file and add the http request function

1. Write lua script file

We name the script file demo.lua, and the content is as follows:

local http = require "resty.http"
local json = require "cjson"

local httpc = http.new()
local res, err = httpc:request_uri("http://127.0.0.1:80/getmes",{
    method = "GET",
    headers = {
            -- ["Authorization"] = "Basic YWRtaW46YWRtaW4=",
            ["Content-Type"] = "application/json",
        },
})

if err ~= nil then
    ngx.log(ngx.ERR, "httpc:request_uri err = ", err)
    return ngx.exit(0)
end

if 200 ~= res.status then
    ngx.exit(res.status)
end

--解析返回的数据
local jsondatanew = json.decode(res.body)["data"]
--得到数据进行其他操作

The above code only describes how to initiate http requests in Lua code. What needs special attention here is that http requests are best placed in the init process. Other processes are not suitable for initiating http requests because of response time or other problems. It is best not to let http requests participate in the logic of access requests. This demonstration is to add it to the init_worker_by_lua_file process and make http requests during the startup initialization phase of openresty.

2. Add dependent library files

If the resty.http module is missing during operation, you need to add several files to the path /usr/local/openresty/lualib/resty. Since the following three files exist, I packaged them into a compressed package. Go here to download: http Lua source code dependent library file download

3. Copy the lua code file

Copy the demo.lua file to the path /usr/local/openresty/nginx/lua/

4. Modify the nginx.conf file

Modify the nginx.conf file, introduce the http request code in the init_worker_by_lua_file process, and modify the content of the nginx.conf file as follows:

#user  nobody;
worker_processes  1;
 
error_log  logs/error.log  error;
error_log  logs/error.log  notice;
error_log  logs/error.log  info;
pid        logs/nginx.pid;
 
events {
    worker_connections  1024;
}
 
 
http {
    include       mime.types;
    default_type  application/octet-stream;
 
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                     '$status $body_bytes_sent "$http_referer" '
                     '"$http_user_agent" "$http_x_forwarded_for"';
    # access_log  logs/access.log  main;
    # error_log   logs/error.log error; 
 
    lua_package_path "/usr/local/openresty/lualib/?.lua;/usr/local/openresty/nginx/lua/?.lua;";
    lua_package_cpath "/usr/local/openresty/lualib/?.so;;";

    init_worker_by_lua_file 	lua/demo.lua;
 
 
    sendfile        on;
    #tcp_nopush     on;
 
    #keepalive_timeout  0;
    keepalive_timeout  65;
    proxy_connect_timeout 3s;
 
    #gzip  on;
 
   
    # HTTPS server
    server {
       listen       80;
       server_name  localhost;
 
       location / {
            #设置代理目的url变量
            proxy_pass https://127.0.0.1;
       }
 
    }
 
}

lua_package_path "/usr/local/openresty/lualib/?.lua;/usr/local/openresty/nginx/lua/?.lua;";

and

init_worker_by_lua_file     lua/demo.lua;

The first sentence is to add the path of the lua code. The second sentence of code is to specify the initialization process init_worker_by_lua_file, which will enter the demo.lua file to perform the http request operation. In my code, the body data is currently only obtained through the http request and converted into json format. , the data is not currently used, you can use the data to implement the functions you want.