Support for custom headers in connection requests

[kukondo]

Problem:

Zero Trust app access solutions, such as Cloudflare Tunnels, are gaining popularity in the self-hosted community. These solutions enable external access to self-hosted applications without the need to open ports. However, they typically require OpenID Connect or SAML-style SSO for authentication, which introduces an intermediate login page before connecting to the application endpoint. As a workaround for client applications that cannot handle this extra authentication step, Cloudflare allows the use of service tokens passed with requests as additional headers.
Link to Cloudflare documentation

Ideal Solution:

Implement support for adding custom headers with custom keys and values when setting up the server connection. This functionality would allow users to set additional headers for requests made to the server. LunaSea is an example of an application that has successfully implemented this feature.
Link to LunaSea documentation
Example image

Alternatives Considered:

The only alternative is to directly forward ports from the internet or to always use a VPN or similar solution when accessing the application remotely. Allowing custom headers to be set for the server connection would enable secure remote access.