[TOC]

Implementation of middleware with nginx openresty

Be careful

In the formal ngx.exec(), you must not output anything, such as ngx.say("debug"), otherwise you will be trapped in redirection

The log will constantly prompt attempt to call ngx.exec after sending out response headers

This should be a common sense problem. We all know that we can't output anything in the header. I forgot,,, and struggled for a long time

install

• Mac

Default installation directory / usr / local / cell / openresty / 1.15.8.2

brew install openresty/brew/openresty

If you encounter the following error message on your Mac

make[1]: *** [lj_folddef.h] Segmentation fault: 11
make[1]: *** Deleting file `lj_folddef.h'
make[1]: *** Waiting for unfinished jobs....
make: *** [default] Error 2
ERROR: failed to run command: gmake -j8 TARGET_STRIP=@: CCDEBUG=-g XCFLAGS='-msse4.2 -DLUAJIT_NUMMODE=2 -DLUAJIT_ENABLE_LUA52COMPAT' CC=cc PREFIX=/usr/local/Cellar/openresty/1.15.8.2/luajit

If reporting this issue please do so at (not Homebrew/brew or Homebrew/core):
  https://github.com/openresty/homebrew-brew/issues

These open issues may also help:
The openresty-debug package should use openresty-openssl-debug instead https://github.com/openresty/homebrew-brew/issues/3
Fails to install OpenResty https://github.com/openresty/homebrew-brew/issues/5
Can't install openresty on macOS 10.15 https://github.com/openresty/homebrew-brew/issues/10

Error: A newer Command Line Tools release is available.
Update them from Software Update in System Preferences or
https://developer.apple.com/download/more/.

To this place, please Download the development plug-in of apple official website Just download the latest Xcode command line tools. I'm confused. I can't download them all night. I thought there was a problem with the official resources, but it was Xunlei's problem

Some people say that brew install *gcc * directly, but I think it's too rude. I didn't do it. If you want to save time, you can try it

• Ubuntu

Default installation directory / usr/local/openresty/nginx/

sudo apt install -y libpcre3-dev libssl-dev perl make build-essential curl\
&& sudo apt-get -y install --no-install-recommends wget gnupg ca-certificates\
&& wget -O - https://openresty.org/package/pubkey.gpg | sudo apt-key add -\
&& sudo apt-get -y install --no-install-recommends software-properties-common\
&& sudo add-apt-repository -y "deb http://openresty.org/package/ubuntu $(lsb_release -sc) main"\
&& sudo apt-get update\
&& sudo apt-get -y install openresty

NGINX configuration

        location ~ /lua_request {
            #default_type 'text/json';
            default_type 'text/html';
            #content_by_lua_file '/Users/liuhao/my-shell/lua/index.lua';
            content_by_lua_file '/Users/liuhao/my-shell/lua/middle.lua';
        }

		# Forward to / / 192.168.56.100
        location @server_100 {
            proxy_pass http://192.168.56.100:80;
		    # The IP information of users will be brought in at the same time. Otherwise, the IP address obtained by the back-end server will be the IP address of the proxy server;
		    proxy_set_header X-Forwarded_For $remote_addr;
        }

		# Forward to / / 192.168.56.101
        location @server_101 {
            proxy_pass http://192.168.56.101:80;
		    # The IP information of users will be brought in at the same time. Otherwise, the IP address obtained by the back-end server will be the IP address of the proxy server;
		    proxy_set_header X-Forwarded_For $remote_addr;
        }

		# Forward to / / 192.168.56.102
        location @server_102 {
            proxy_pass http://192.168.56.102:80;
		    # The IP information of users will be brought in at the same time. Otherwise, the IP address obtained by the back-end server will be the IP address of the proxy server;
		    proxy_set_header X-Forwarded_For $remote_addr;
        }

lua code

This is a forwarding case, a simple scenario

If you want to do more complex functions, such as a distributed swap save, you can use consistency hash

You can also cache the unique value of user name to the following, and then forward IP as required

In fact, the most important thing about this case is to learn that you can write middleware and do data filtering in lua

local restyMemcached = require "resty.memcached"

--Obtain GET Request parameters,_name Is the parameter name,If it's something else like ID Namely_id
local name = ngx.var.arg_name

 --lua Initialization memcached
 local memcached ,err = restyMemcached:new()
 if not memcached then
    return ngx.say("memcached init failed: ",err)
 end

 -- Connect memcached
 local ok,err = memcached:connect("127.0.0.1",11211)
 if not ok then
    return ngx.say("connect failed: ",err)
 end

 -- from memcached Get parameters
 local value,flags,err =memcached:get("name-"..name)
 if err then
    return ngx.say("get failed: ",err)
 end
--Be sure to pay attention,When underneath ngx.exec()When,You must not use any output at the front,I just forgot that,Stuck for half a day
--  ngx.say("request key:", name," cache:", value)

 --This is not real switch,lua No, switch,This is through lua Of table To realize the false switch
 local switch = {
    ["100"] = function()
        --@server_100 see nginx Defined,Hand NGINX Forwarding
        -- ngx.say("switch:100")
        ngx.exec("@server_100")
    end,
    ["101"] = function()
        --@server_101 see nginx Defined,Hand NGINX Forwarding
        -- ngx.say("switch:101")
        ngx.exec("@server_101")
    end,
    ["102"] = function()
        --@server_102 see nginx Defined,Hand NGINX Forwarding
        -- ngx.say("switch:102")
        ngx.exec("@server_102")
    end,
}
--Obtained by subscript at switch Data in
local server = switch[value]
if server then
    --implement switch Lower case
    --Be sure to pay attention,When here ngx.exec()When,You must not use any output at the front,I just forgot that,Stuck for half a day
    server()
    return
end
return ngx.say("server not exist")

Request test

Send request

curl http://localhost/lua_request?name=100
curl http://localhost/lua_request?name=101
curl http://localhost/lua_request?name=102

You can see that all three machines have received the request

End