update

app.lua

@@ -19,7 +19,8 @@ local api_version, api_pxoxy_pass_url_indicator = uri:match("/?([^/]+)/?(.*)")
 ngx.say("api_version: ", api_version)
 ngx.say("api_pxoxy_pass_url_indicator: ", api_pxoxy_pass_url_indicator)
 pass_url = api_pxoxy_pass_url_indicator
-ngx.req.set_header("upstream", pass_url)
+local upstream_dict = ngx.shared.upstream_dict
+upstream_dict:set("upstream", pass_url)
 pass_url = pass_url:gsub("http/", "http://")
 pass_url = pass_url:gsub("https/", "https://")
 ngx.say("pass_url: ", pass_url)

nginx.conf

@@ -7,6 +7,8 @@ http {
     include       mime.types;
     default_type  application/octet-stream;
 
+    lua_shared_dict upstream_dict 10m;
+
     sendfile        on;
     keepalive_timeout  65;
 
@@ -23,7 +25,7 @@ http {
                 -- ngx.var.proxy_pass = ngx.var.uri
                 ngx.var.upstream = 'https://baidu.com';
             }
-            proxy_pass $http_upstream;
+            proxy_pass $ngx.shared.upstream_dict["upstream"];
         }
     }
 }