XMPP Server - Prosody

[djxx]

I was actually looking into Snikket again last night. Back when I did my first packaging of XMPP, Snikket was still a bit too limited in features. I'll take another look at Snikket, but I suspect it will have the same cert requirements as part of the XMPP protocol.

And @girish , I don't remember perfectly, but based on my notes above the cert was the only thing I couldn't work around in the app package approach. While checking out Snikket I'll confirm if it also needs it.

[djxx]

Research done - it is indeed a limitation of Snikket's implementation of XMPP. from https://snikket.org/faq/:

[djxx]

The way both Snikket and Cloudron apps work, it would "technically" be a different domain to allow your XMPP usernames to be like: user@domain.com , instead of the uglier user@chat.domain.com . The SRV records are trivial, and the real limitation as far as Cloudron is concerned is the app getting the cert with the TLD.

I guess there may be other apps in the future that would need the primary cert in order to verify trust between the TLD and the app itself - so perhaps this could be a new app option?

Also, Snikket intends to be a "one and done" installation, and it packages its own TURN/STUN server. For that reason, I think it's not ideal to use as the XMPP solution since it will make the app heaver than it needs to be, and require more ports.

[LoudLemur]

I had AI look at this, but it wasn't very fruitful. It suggests using Cloudron's wildcards and, for Prosody, using its ACME plugin which can obtain certificates:"Let's dive into the specific technical challenges and potential solutions for using Prosody on Cloudron:

1. Domain Flexibility with Prosody:
   Prosody is indeed more flexible than Snikket in this regard. You can configure Prosody to use different domains for XMPP addresses and the web portal. The key configuration options you'd need to focus on are:

VirtualHost "example.com"
  -- XMPP domain configuration

http_host = "chat.example.com"
  -- Web interface domain

This separation isn't possible with Snikket's current setup.

2. Certificate Handling:
   The core issue here is obtaining a certificate for example.com when your Cloudron app is hosted at chat.example.com. Prosody itself doesn't solve this, but there are potential workarounds:

a) Use Cloudron's wildcard certificate: If Cloudron provides a wildcard cert for *.example.com, you could use this for both the chat subdomain and the main domain.

b) Manual certificate injection: You could manually obtain a certificate for example.com and inject it into the Prosody container. This would require modifying the Cloudron app to allow for custom certificate paths:

ssl = {
    certificate = "/path/to/custom/fullchain.pem";
    key = "/path/to/custom/privkey.pem";
}

c) ACME plugin: Prosody has an ACME plugin that can obtain certificates. You'd need to ensure the Cloudron app has the necessary permissions to write these certificates and that the DNS challenge is used instead of HTTP:

plugin_paths = { "/usr/lib/prosody/modules" }
modules_enabled = {
    "acme"
}
acme = {
    provider = "letsencrypt",
    challenge = "dns-01"
}

3. SRV Records:
   Cloudron should allow you to set custom DNS records. You'd need to add:

_xmpp-client._tcp.example.com. IN SRV 0 5 5222 chat.example.com.
_xmpp-server._tcp.example.com. IN SRV 0 5 5269 chat.example.com.

4. Cloudron Integration:
   The existing GitHub repo is a start, but you'd need to modify it to:

• Allow for custom domain configuration
• Implement one of the certificate solutions mentioned above
• Possibly add a script to automatically update SRV records via Cloudron's API

5. Reducing Overhead:
   Unlike Snikket, Prosody doesn't include a TURN/STUN server by default. You could either:
   a) Use an external TURN/STUN service
   b) Implement a lightweight TURN/STUN server as a separate Cloudron app

To move forward:

1. Fork the existing Cloudron-Prosody repo and start implementing these changes.
2. Engage with Cloudron's development team about adding an option for apps to use the primary domain certificate. This would solve many of these issues at the platform level.
3. Consider implementing a custom module for Prosody that interfaces with Cloudron's API for dynamic configuration and certificate management.

This approach should address the specific technical challenges you're facing with implementing an XMPP server on Cloudron while taking advantage of Prosody's flexibility. The key will be integrating Prosody's configurability with Cloudron's app structure and API."

[djxx]

@girish - Given that the only blocker (that I know of so far) is the TLD certificate availability, would it be a decent workaround to package this entire thing as an application, and then run a one-time command to symlink the TLD certificate into the application directory? This would allow the sys admin to choose which application deserves access to the TLD certificate, ensure the app always has access to the latest certificate, and work around the current limitation of apps not being able to request the TLD cert.

[djxx]

@girish - checking in again. I have another server I'm considering moving to Cloudron - but I need XMPP.

[girish]

@djxx Just re-reading this thread again. From what I gathered, the app can be installed in app.domain.com but can use handles like @domain.com . For that matter, it can use handles like @handle.domain.com as well. All a matter of configuration . For this, the app requires certs of whatever the handle domain is.

I guess we need some sort of option field in the 'tls' addon - https://docs.cloudron.io/packaging/addons/#tls . But I am unable to quickly think of a way how to specify this in the manifest

[girish]

Is https://github.com/DerekJarvis/cloudron-prosody still the latest code ? If I build that app, does it work?

[djxx]

I will take another look at building the custom app, as well as the TLS option and report back when I'm ready.

[djxx]

Small update - made good progress. What's working so far:

• XMPP server starts up, messages can be sent/received
  • this includes the pretty user@domain.com username
• LDAP Auth works, so users use their own accounts
• App health check

What doesn't work: anything related to HTTP endpoints (e.g. file uploads) . I've opened a ticket here: https://forum.cloudron.io/topic/13539/custom-app-httpport-not-being-proxied

[djxx]

Big update - I'm ready for your help @girish .

Repo: https://github.com/DerekJarvis/cloudron-prosody
Docker Image: derekjarvis/cloudron-prosody:20250406-042328-86345387d

What's working:

Everything.

This is a full-fledged XMPP server with:

• Healthcheck
• TURN server for jingle calling (voice and video)
• Uses LDAP for auth and automatically works for all users
• Supports sending/receiving files and images
• Supports message carbons (sync messages between devices)
• Supports standard (pretty) accounts like user@domain.com

(Direct TLS failing is intentional because it's deprecated and our upstream doesn't bother supporting it)

Approach:

I forked from a repository that has a good Prosody docker image with VERY secure defaults. I actually had to loosen a couple to make it more user friendly (like not requiring OMEMO). I added on the modules that make it even more useful (like HTTP upload for file attachments, TURN for jingle calls). I tried to make the majority of changes in our own files to make it easier to compare to upstream. I used Cloudron services (like LDAP, TURN) instead of running extra services in the container.

Help Needed:

There are a few VERY hacky things I had to do to make this work. Only one is a total blocker for real deployment by others, the others are all "nice to have" improvements.

TLD (Top-Level Domain) certs (blocker)

XMPP needs the TLD cert to allow the standard (and pretty) usernames like user@domain.com. Right now, there's no way for a Cloudron app to request the TLD cert. To work around this I did the following:

• Made a storage volume for the app
• Copied all the certs into the storage volume (yes, this is a very bad idea)
  • cp -f /home/yellowtent/platformdata/nginx/cert/* /mnt/HC_Volume_102134826/app_xmpp/
• Have the app use the certs it needs and then delete everything else

Aliases needed (nice to have)

The app is installed under the "xmpp" domain, and 4 aliases must be defined in the app, and also in the DNS records:

• conference.domain.com
• proxy.domain.com
• pubsub.domain.com
• upload.domain.com

It would be great if the Manifest allowed us to specify additional aliases the app needs, and also added the DNS records for those if the Cloudron instance is using a DNS API

SRV Records (nice to have)

XMPP uses SRV records to give information about the XMPP servers for a domain. Specifically:

• _xmpp-client._tcp.domain.tld port 5222
• _xmpps-client._tcp.domain.tld port 5223
• _xmpp-server._tcp.domain.tld port 5269

Add these manually, and your app will work fine.

It would be ideal if Cloudron allowed specifying additional DNS records that should be created if the Cloudron instance is using a DNS API.

Admin users (nice to have)

I couldn't find a way to identify Cloudron Admin users through LDAP. Prosody supports specifying an LDAP query to indicate who is an admin of the XMPP server.

It would be ideal if there was an LDAP query that could identify Admin users, and then Prosody would mark those users as admins as well.

External IP for checks (nice to have)

Prosody has a very convenient check function which will check for common errors. One of the things it checks for is if it thinks it is reachable by checking the DNS records it uses against the IP addresses it knows it has. So in the Prosody config you can tell it the known IP addresses for the server, and the check function will compare that to the DNS records to confirm the server is reachable.

It would be ideal if we have an environment variable for the server's primary IP address. With this the checks would not show so many false positives.

TLD environment variable (nice to have)

Prosody needs to know the TLD it is serving. I did not find an environment variable for this, so I hacked one using bash:
export DOMAIN=${CLOUDRON_WEBADMIN_ORIGIN#https://my.}

It would be ideal if Cloudron exposed an environment variable for the TLD.

Other Comments

The #1 reason I use XMPP is for self-hosted private chat. The #2 reason is it's how I have a virtual phone number for SMS. I use https://jmp.chat to get a VERY CHEAP sms number and use XMPP on all my devices to communicate with people through SMS on convenient chat apps like Gajim and Conversations.

[jdaviescoates]

@djxx great work! Many thanks for your efforts! hopefully @staff can assist to get this over the line and into the app store!

[nebulon]

@djxx very nice! I just tried to quickly test this and building from your repo, the app fails to start with the following error:

cp: cannot stat '/media/Extra Storage/app_xmpp/*': No such file or directory

probably some oversight there, but don't have time to dig into this just now.

[djxx]

@nebulon - Correct. You would need to make a volume called "Extra Storage", mount it onto the app, and have a folder under it called app_xmpp where you copy the sub-domain and TLD certs you need (I just copied all of them). This is an ugly workaround for the TLD cert not being available to the app through the manifest configuration.

You would also need to add a few alias domains and DNS records manually.

[djxx]

I guess some clear set up instructions would help

• install the app to the 'xmpp' subdomain
• add extra DNS CNAME/A records pointing to the same server:
  • pubsub
  • proxy
  • upload
  • conference
• add these domains as aliases for the app
• add DNS SRV records:
  • _xmpp-client._tcp.domain.tld port 5222
  • _xmpps-client._tcp.domain.tld port 5223
  • _xmpp-server._tcp.domain.tld port 5269
• make a storage volume called "Extra Storage"
• mount the storage volume to the app
• copy certs into the storage under the subdirectory app_xmpp
  • for my server, the command looks like this (run in cloudron directly, not in the app terminal):
  • cp -f /home/yellowtent/platformdata/nginx/cert/* /mnt/HC_Volume_102134826/app_xmpp/
• restart the app to make sure it's starting up with all pieces in place (extra domains, DNS records, and certs)

Then you can check for compliance with these two tools:

• https://compliance.conversations.im
• https://connect.xmpp.net/