In order to set the headers of the upstream request, I use `ngx.req.set_header` in `rewrite_by_lua_block`, but my upstream endpoint cannot receive such header.

          > @agentzh I get a problem here.In order to set the headers of the upstream request, I use `ngx.req.set_header` in `rewrite_by_lua_block`, but my upstream endpoint cannot receive such header. here is my conf.

upstream foo {
        server 127.0.0.1:6666 weight=1;
    }

    server {
        listen 8001;
        location / {
            rewrite_by_lua_block {
                ngx.req.set_header("Connection", "Upgrade")
            }
            proxy_pass http://foo;
        }
    }
    server {
        listen 8002;
        location / {
            proxy_set_header Connection '';
            rewrite_by_lua_block {
                ngx.req.set_header("Connection", "Upgrade")
            }
            proxy_pass http://foo;
        }
    }

request send by 8001 port still cannot get the header "Connection: Upgrade"

Have you solved this problem?I have a similar problem，

Originally posted by @djfsb in https://github.com/openresty/lua-nginx-module/issues/437#issuecomment-948387694

Start by reproducing the two configurations using rewrite_by_lua_block, ngx.req.set_header, proxy_set_header, and proxy_pass, then inspect what the upstream on port 6666 receives. Done means determining whether the Connection header can be set this way and documenting or correcting the behavior.