Client Settings Policy

[kate-osborn]

Add a ClientSettingsPolicy API that allows Cluster Operators and Application Developers to configure the behavior of the connection between the client and NGINX.

To begin, the Client Settings Policy will include the following NGINX directives:

• client_max_body_size
• client_body_timeout
• keepalive_requests
• keepalive_time
• keepalive_timeout

Use Cases:

• As a Cluster Operator, I want to set defaults for client settings that will work for most applications so that most Application Developers will not have to tweak these settings.
• As an Application Developer, I want to be able to configure client settings for my application based on its behavior or requirements.
• As an Application Developer, I want to override the defaults for client settings set by the Cluster Operator because the defaults do not satisfy my application's requirements or behavior.

Directives:

### Tasks
- [ ] #1603
- [ ] https://github.com/nginxinc/nginx-gateway-fabric/issues/1759
- [ ] https://github.com/nginxinc/nginx-gateway-fabric/issues/1754
- [ ] https://github.com/nginxinc/nginx-gateway-fabric/issues/1760
- [ ] https://github.com/nginxinc/nginx-gateway-fabric/issues/1792
- [ ] https://github.com/nginxinc/nginx-gateway-fabric/issues/1762
- [ ] https://github.com/nginxinc/nginx-gateway-fabric/issues/1763
- [ ] https://github.com/nginxinc/nginx-gateway-fabric/issues/1898

[mpstefan]

This does not seem to include #483 or #1398 - when are we able to bring those in?

[kate-osborn]

This does not seem to include #483 or #1398 - when are we able to bring those in?

@mpstefan those will be separate epics as they are both new policies:

• https://github.com/nginxinc/nginx-gateway-fabric/blob/main/docs/proposals/nginx-extensions.md#upstream-settings
• https://github.com/nginxinc/nginx-gateway-fabric/blob/main/docs/proposals/nginx-extensions.md#proxy-settings