How to enhance Caddy's basic_auth?

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Hello fellow selfhoster! on my debian server I use Caddy as reverse proxy, and would like to protect some services and files with a password. I would like, however, to be able to access some protected files programmatically, from a script.
using Caddy's built-in basic_auth works as intended, but I'd like to be able to use a login form instead of just a browser prompt. This is AFAIK not possible, so I'm looking for alternatives. Any idea?

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I use https://github.com/nosduco/nforwardauth for this purpose

There is an example implementation for caddy in https://github.com/nosduco/nforwardauth/tree/main/examples/caddy-v2

or maybe voidauth could do it https://sh.itjust.works/post/42016490

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Developer of VoidAuth here, you could give that a try! If you have any issues or questions I can help
VoidAuth

It does support basic_auth to ProxyAuth protected domains, so you can set up a user for that purpose. Docs for that are here: ProxyAuth

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How does programmatic access tie into the desire for a login form?

Either way, you can do a login form -> basic auth forwarding page by rigging up some simple JS, or access programmatically in a direct way by simply setting a manual Authorization header.

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This looks very interesting! I see that it supports users groups, would it be possible to create "named access policies" (like "admin_only_policy", "group_XXX_policy" ecc) and then assign them to the various services directly in the Caddyfile?
thank you very much!

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How does programmatic access tie into the desire for a login form?

I would like to keep files with "private" information protected from public access, but I would like to access them from a script. An example: i wrote a karaoke application to use with my friends, they have to go to a webpage and select the songs they like, and then the karaoke app connects to the server to get the updated preference file. I would like that the users had a "nice login form" to select their songs, and then I'd like my karaoke app to easily download the file while still keeping it password-protected

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I don’t think you could do that directly in the Caddyfile, but you can create those groups/policies inside VoidAuth and assign them to users there.

The steps would be to (in VoidAuth) create the access group/policy, create the ProxyAuth Domain (protected.example.com/*) with the allowed group(s), make sure the user(s) have that group, then in Caddy add the forward_auth directive to the same route you want to protect.

Then when you go to access that route in a browser it will redirect you to VoidAuth login, or if you pass an Authentication header with Basic Auth (like when using an API) it will use that.

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I don’t use Caddy but Keycloak may be what you’re looking for.

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Yeah, I believe you don’t need to extend Caddy at all for that.

Add a properly-formatted Authorization header to any requests you make to the server and it’ll work. See Wikipedia page for header string format:

https://en.wikipedia.org/wiki/Basic_access_authentication

On the webpage side, I’d have the login form make a POST to your login endpoint using a basic auth header to pull a JWT that acts as a “real” auth key for other pages.

This is all assuming you want to stick with basic auth as opposed to a more heavyweight option.

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I use Authelia powered by LLDAP with Caddy to protect services. For accessing files I use copyparty, it can hook into Authelia for user auth.

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I already looked into Authelia, and the "problem" I encountered is that it does not support "named policies" (I don't know the actual name): what I mean is to be able to create "only_admin_policy", "only_registered_users_policy" etc, and then in Caddy to be able to say something like this

service1.website.com {
    reverse_proxy container1:1234
    apply_policy only_admin_policy
}
service2.website.com {
    reverse_proxy container2:1234
    apply_policy only_registered_users_policy
}
service3.website.com {
    reverse_proxy container3:1234
}

Instead if I understood correctly (and I would gladly be proved wrong) this is not possible with Authelia, as these policies have to be specified inside Authelia, so I would have two different configurations in two different places instead of having everything in the Caddyfile

I hope I explained well what I mean

thanks for the help!

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This was actually pretty interesting until I found out that Caddy is not yet supported

Thank you anyway!

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yes, it can do that, assuming you are using LDAP or have set up users/groups in the Authelia config. you don't need to set it up in the caddyfile though, you can handle everything from Authelia's end. for example, here is a typical protected item from my caddyfile.

# this is a bit of code at the top that I use for every protected item, and call it each time to save space
(protected) {
	tls /ssl/home-cert.pem /ssl/home-key.pem
	forward_auth :4100 {
		uri /api/verify?rd=https://auth.myurl.xyz/
		copy_headers Remote-User Remote-Groups Remote-Name Remote-Email
		header_up Host {upstream_hostport}
	}
	encode gzip
}

# UptimeKuma
uptime.myurl.xyz {
    # now to call the code above for this item
	import protected *
	reverse_proxy :4000
}

that's all I need in my caddyfile, just the bits that forward the information about the user to each site to log them in. I can then handle all the auth rules like saying which sites are only for admins or users in the Authelia config. since I use LDAP, I can set up the groups in that, then just specify which sites are DENY or TWO_FACTOR for each group in the Authelia config. or even in the apps themselves, if they support LDAP like Jellyfin and Forgejo.

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Check out supertokens.io

I see voidauth already mentioned, great setup also

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How to enhance Caddy's basic_auth?