Connection pooling to upstream in Nginx - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is connection pooling in the context of nginx upstream servers?

Connection pooling is a technique where nginx reuses existing connections to upstream servers instead of opening a new connection for every client request. This improves performance by reducing connection overhead.

beginner

Which nginx directive enables connection reuse to upstream servers?

The directive keepalive inside the upstream block enables connection pooling by keeping connections open for reuse.

intermediate

How do you configure nginx to keep 32 connections alive to an upstream server?

Inside the upstream block, add keepalive 32; to allow nginx to keep 32 idle connections open for reuse.

beginner

What is the benefit of using connection pooling with upstream servers in nginx?

It reduces the time and resources spent establishing new TCP connections, lowers latency, and improves throughput by reusing existing connections.

intermediate

Can connection pooling be used with HTTP/1.1 and HTTP/2 upstream connections in nginx?

Connection pooling with keepalive works with HTTP/1.1 upstream connections. For HTTP/2, nginx handles multiplexing differently and does not use the same keepalive directive.

Which nginx directive controls the number of idle connections kept alive to upstream servers?

A keepalive

B proxy_pass

C worker_connections

D client_max_body_size

The keepalive directive inside the upstream block sets how many idle connections nginx keeps open for reuse.

What is the main advantage of connection pooling in nginx upstreams?

A Caching static files on the server

B Increasing the number of worker processes

C Reusing existing connections to reduce latency

D Encrypting client connections

Connection pooling reuses existing connections, which reduces the time needed to establish new connections and lowers latency.

Where do you place the keepalive directive to enable connection pooling?

A Inside the <code>server</code> block

B Inside the <code>location</code> block

C Inside the <code>http</code> block

D Inside the <code>upstream</code> block

The keepalive directive must be set inside the upstream block to enable connection pooling.

If you set keepalive 16; in an upstream block, what does it mean?

A Nginx keeps up to 16 idle connections open to upstream servers

B Nginx limits total connections to 16

C Nginx closes connections after 16 seconds

D Nginx uses 16 worker processes

This setting keeps up to 16 idle connections open for reuse to improve performance.

Does connection pooling with keepalive work the same way for HTTP/2 upstream connections?

A Only if HTTP/2 is disabled

B No, HTTP/2 uses multiplexing and does not rely on keepalive

C Yes, it works exactly the same

D Only for HTTPS connections

HTTP/2 multiplexes multiple streams over a single connection, so nginx does not use the keepalive directive for HTTP/2 upstreams.

Explain how connection pooling works in nginx and why it improves performance.

Think about how opening fewer new connections saves time.

Describe how to configure nginx to keep 20 idle connections alive to an upstream server.

Remember the keepalive directive goes inside the upstream block.