OpenResty默认没有提供Http客户端，需要使用第三方提供的插件
我们可以从github上搜索相应的客户端，比如https://github.com/pintsized/lua-resty-http

安装方法：将 lua-resty-http/lib/resty/ 目录下的 http.lua 和 http_headers.lua
两个文件拷贝到 /usr/local/openresty/lualib/resty 目录下即可
(假设 OpenResty 安装目录为 /usr/local/openresty)local res, err = httpc:request_uri(uri, {  method = "POST/GET",  ---请求方式query = str,  ---get方式传参数body = str,     ---post方式传参数path = "url" ----路径headers = {  ---header参数["Content-Type"] = "application/json",  }
})  示例：编写模拟请求天猫的查询--引入http模块
local http = require("resty.http")
--创建http客户端实例
local httpc = http:new()local resp,err = httpc:request_uri("https://list.tmall.com",
{method = "GET",    ---请求方式--path="/search_product.htm?q=ipone",query="q=iphone",    ---get方式传参数body="name='jack'&age=18",    ---post方式传参数path="/search_product.htm",    ----路径---header参数headers = {["User-Agent"]="Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.111 Safari/537.36"}
})
if not resp thenngx.say("request error:",err)return
end
--获取状态码
ngx.status = resp.status--获取响应信息
--响应头中的Transfer-Encoding和Connection可以忽略，因为这个数据是当前server输出的。
--获取遍历返回的头信息for k, v in pairs(resp.headers) doif k ~= "Transfer-Encoding" and k ~= "Connection" thenngx.header[k] =vendif type(v) == "table" then  ngx.log(ngx.WARN,"table:"..k, ": ", table.concat(v, ", "))  else  ngx.log(ngx.WARN,"one:"..k, ": ", v)  end
end
ngx.say("end")
--响应体
ngx.say(resp.body)httpc:close()httpc:close()# 后台日志
# /usr/local/openresty/nginx]# tail -f logs/debug.log
2019/08/23 17:58:04 [warn] 25373#0: *131 [lua] testhttp02.lua:32: one:ufe-result: A6, client: 192.168.10.164, server: www.server1.com, request: "GET /testhttp02 HTTP/1.1", host: "192.168.10.164"
2019/08/23 17:58:04 [warn] 25373#0: *131 [lua] testhttp02.lua:32: one:Date: Fri, 23 Aug 2019 09:58:04 GMT, client: 192.168.10.164, server: www.server1.com, request: "GET /testhttp02 HTTP/1.1", host: "192.168.10.164"
2019/08/23 17:58:04 [warn] 25373#0: *131 [lua] testhttp02.lua:32: one:Location: https://login.taobao.com/jump?target=https%3A%2F%2Flist.tmall.com%2Fsearch_product.htm%3Ftbpm%3D1%26q%3Diphone, client: 192.168.10.164, server: www.server1.com, request: "GET /testhttp02 HTTP/1.1", host: "192.168.10.164"
2019/08/23 17:58:04 [warn] 25373#0: *131 [lua] testhttp02.lua:32: one:Connection: keep-alive, client: 192.168.10.164, server: www.server1.com, request: "GET /testhttp02 HTTP/1.1", host: "192.168.10.164"
2019/08/23 17:58:04 [warn] 25373#0: *131 [lua] testhttp02.lua:32: one:EagleEye-TraceId: 0bfa16f315665542845385751e42fa, client: 192.168.10.164, server: www.server1.com, request: "GET /testhttp02 HTTP/1.1", host: "192.168.10.164"
2019/08/23 17:58:04 [warn] 25373#0: *131 [lua] testhttp02.lua:32: one:Strict-Transport-Security: max-age=0, client: 192.168.10.164, server: www.server1.com, request: "GET /testhttp02 HTTP/1.1", host: "192.168.10.164"
2019/08/23 17:58:04 [warn] 25373#0: *131 [lua] testhttp02.lua:32: one:Content-Length: 0, client: 192.168.10.164, server: www.server1.com, request: "GET /testhttp02 HTTP/1.1", host: "192.168.10.164"
2019/08/23 17:58:04 [warn] 25373#0: *131 [lua] testhttp02.lua:32: one:Timing-Allow-Origin: *, client: 192.168.10.164, server: www.server1.com, request: "GET /testhttp02 HTTP/1.1", host: "192.168.10.164"
2019/08/23 17:58:04 [warn] 25373#0: *131 [lua] testhttp02.lua:32: one:Server: Tengine/Aserver, client: 192.168.10.164, server: www.server1.com, request: "GET /testhttp02 HTTP/1.1", host: "192.168.10.164"

-------------------------------------------------------
发现报错
request error :no resolver defined to resolve "list.tmall.com"此错误是因为要配置DNS解析器resolver 8.8.8.8，否则域名是无法解析的。
在nginx.conf配置文件中 http模块加上resolver 8.8.8.8; Google提供的免费DNS服务器的IP地址
配置好后，重启nginx---------------------------------------------------------访问https错误，因为我们访问的https，需要配置ssl证书
在nginx配置文件中，server虚拟主机模块设置lua_ssl_verify_depth 2;
lua_ssl_trusted_certificate "/etc/ssl/certs/ca-bundle.crt";--------------------------------------------------------http模块应用场景很多，这里只简单介绍了一下http模块的使用还有很多openresty模块，可以参考 https://github.com/bungle/awesome-resty
以suning.com为例：local http = require("resty.http")
--创建http客户端实例
local httpc = http:new()local resp,err = httpc:request_uri("http://issm.suning.com",
{method = "GET",path="/productDetail_P11271.htm",headers = {["User-Agent"]="Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.111 Safari/537.36"}
})
if not resp thenngx.say("request error:",err)return
end
--获取状态码
ngx.status = resp.status--获取响应信息
--响应头中的Transfer-Encoding和Connection可以忽略，因为这个数据是当前server输出的。
for k,v in pairs(resp.headers) doif k ~= "Transfer-Encoding" and k ~= "Connection" thenngx.header[k] =vend
end--响应体
ngx.say(resp.body)httpc:close()

# cat /usr/local/openresty/nginx/conf/nginx.conf
worker_processes  4;#pid        logs/nginx.pid;
events {worker_connections  10240;
}http {include       mime.types;default_type  text/html;sendfile        on;keepalive_timeout  65;resolver 8.8.8.8;server {listen       80;server_name  www.server1.com;lua_ssl_verify_depth 2;lua_ssl_trusted_certificate "/etc/ssl/certs/ca-bundle.crt";location /tmall {access_by_lua_file /usr/local/lua/tmall.lua;}location / {root   html;index  index.html index.htm;}error_page   500 502 503 504  /50x.html;location = /50x.html {root   html;}}}

# cat /usr/local/lua/tmall.lua
--引入http模块
local http = require("resty.http")
--创建http客户端实例
local httpc = http:new()local resp,err = httpc:request_uri("https://list.tmall.com",
{method = "GET",    ---请求方式--path="/search_product.htm?q=ipone",query="q=iphone",    ---get方式传参数body="name='jack'&age=18",    ---post方式传参数path="/search_product.htm",    ----路径---header参数headers = {["User-Agent"]="Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.111 Safari/537.36"}
})
if not resp thenngx.say("request error:",err)return
end
--获取状态码
ngx.status = resp.status--获取响应信息
--响应头中的Transfer-Encoding和Connection可以忽略，因为这个数据是当前server输出的。
--获取遍历返回的头信息for k, v in pairs(resp.headers) doif k ~= "Transfer-Encoding" and k ~= "Connection" thenngx.header[k] =vendif type(v) == "table" then  ngx.log(ngx.WARN,"table:"..k, ": ", table.concat(v, ", "))  else  ngx.log(ngx.WARN,"one:"..k, ": ", v)  end
end
ngx.say("end")
--响应体
ngx.say(resp.body)httpc:close()