Opened 3 years ago

Closed 3 years ago

#2220 closed defect (invalid)

2 way communication over single tcp connection

Reported by: rajatgoyal247341@… Owned by:
Priority: minor Milestone:
Component: documentation Version: 1.19.x
Keywords: Cc:
uname -a: Linux 6fc1a56e859c 4.14.232-176.381.amzn2.x86_64 #1 SMP Wed May 19 00:31:54 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
nginx -V: nginx version: nginx/1.19.10 (nginx-plus-r24-p1)
built by gcc 4.8.5 20150623 (Red Hat 4.8.5-44) (GCC)
built with OpenSSL 1.0.2k-fips 26 Jan 2017
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib64/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/ --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --user=nginx --group=nginx --with-compat --with-file-aio --with-threads --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_flv_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_random_index_module --with-http_realip_module --with-http_secure_link_module --with-http_slice_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module --with-http_v2_module --with-mail --with-mail_ssl_module --with-stream --with-stream_realip_module --with-stream_ssl_module --with-stream_ssl_preread_module --build=nginx-plus-r24-p1 --with-http_auth_jwt_module --with-http_f4f_module --with-http_hls_module --with-http_session_log_module --with-cc-opt='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -DIP_BIND_ADDRESS_NO_PORT=24 -fPIC' --with-ld-opt='-Wl,-z,relro -Wl,-z,now -pie'


I am having a requirement where my grpc-servers are behind firewall. So all incoming connections to these servers are blocked.

I want to use grpc as tunnel, where these servers will initiate the tcp connection with a publicly exposed load balancer. I chose nginx as load balancer for POC. So my idea is :

a) Grpc servers will initiate a long-lived tcp connection with nginx by calling a RPC. Nginx will have all these servers defined under upstream group. This way each upstream server will have 1 connection with nginx.
b) A Grpc client calls nginx, and nginx will forward the request to any of upstream server. In-doing so nginx should use the connection established in step-a than creating a new connection to upstream server.
But when I tested with above set-up, I see that it is creating a new connection than using the already established connection with upstream server.

Can you please suggest if this is possible ? How differently should I run the grpc server / nginx conf. Can any other load-balancer server above purpose than nginx ?

Change History (1)

comment:1 by Maxim Dounin, 3 years ago

Resolution: invalid
Status: newclosed

To instruct nginx to cache connections to upstream servers you have to use the keepalive directive in the appropriate upstream{} block. If you have further questions on how to configure nginx, please consider using support options available.

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