feat(nginx): add config to update the backlog of nginx

[sambhav-jain-16]

What?

Add a configurable backlog value for nginx for all kraken services

Why?

Although the max value of the accept queue in the host is

cat /proc/sys/net/core/somaxconn
4096

The actual value still defaults to the accept queue limit from nginx (511) since
$$\text{Send-Q} = \min(\text{Application Backlog}, \text{somaxconn})$$

ss -lnt
State             Recv-Q            Send-Q                        Local Address:Port                          Peer Address:Port            Process
LISTEN            0                 511                                 0.0.0.0:8351                               0.0.0.0:*
LISTEN            0                 511                                 0.0.0.0:9003                               0.0.0.0:*

This has caused listen drops on the hosts during sudden load (such as prefetching).
This change aims to add a config option to set this limit. If config is not defined, the current defaults are used for backward compatibility.

[Copilot]

Pull request overview

Adds a configurable listen_backlog setting to the nginx config generation so deployments can tune the TCP accept backlog used by nginx listen directives.

Changes:

• Introduces listen_backlog as a new nginx.Config YAML setting and injects it into template params.
• Updates nginx component templates (agent/origin/proxy/tracker/build-index) to optionally render backlog=<value> on listen directives.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
nginx/nginx.go	Adds ListenBacklog to config and injects listen_backlog into template params.
nginx/config/agent.go	Adds optional backlog=... to the agent listen directive.
nginx/config/origin.go	Adds optional backlog=... to the origin listen directive.
nginx/config/proxy.go	Adds optional backlog=... to the proxy listen directive(s).
nginx/config/tracker.go	Adds optional backlog=... to the tracker listen directive.
nginx/config/build-index.go	Adds optional backlog=... to the build-index listen directive.

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated no new comments.