feat(docker): Add IPv6 dual-stack support to nginx

[gauravahujame]

Description

Adds IPv6 support to nginx configuration and includes healthcheck for Docker deployments.

Problem

Since Docker Engine v26, containers keep IPv6 enabled on the loopback interface by default. The current nginx configuration only listens on IPv4, which can cause connectivity issues when applications or healthchecks resolve localhost to ::1 (IPv6).

Solution

• Added listen [::]:8080; directive to nginx.conf for dual-stack support (separate IPv4 and IPv6 sockets)
• Added healthcheck to docker-compose.yml using explicit IPv4 address for maximum compatibility

Testing

• ✅ Verified nginx listens on both IPv4 (0.0.0.0:8080) and IPv6 (:::8080)
• ✅ Confirmed healthcheck passes with wget -q --spider http://127.0.0.1:8080/
• ✅ Tested connectivity via localhost, 127.0.0.1, and [::1]

Benefits

• Improved compatibility with modern Docker environments
• Enables proper container health monitoring

Note

Uses separate IPv4/IPv6 sockets for standard dual-stack configuration. On systems with IPv6 completely disabled at the kernel level (rare), users can remove the listen [::]:8080; line from nginx.conf.

Related

• Addresses similar issue discussed in home-assistant/addons