Cosmos Cloud Writeup

Eji1700
2025-10-05T06:48:40Z

I'm just copy pasting my reddit writeup since that's where the creator is active. For those curious the basic idea of cosmos (https://cosmos-cloud.io/) is home server with a push towards default safety stuff. Reverse proxy over your docker containers configured to not see beyond their world sort of thing so you can safely control access. I believe it's a one person project and still very much in development, but given that so many people just drop "roll your own, you just need to learn...." as the solution I find this to be vastly preferable, and maybe better than things like CasaOS

Post:
I've had less time than I hoped to really poke at this, so it's a bit rambly/stream of consciousness. Figured I'd put this up as a data point for anyone either considering cosmos, or maybe as some feedback. If anyone wants more detail on a specific part I'll gladly dive in, but for now if I don't put this up I never will. A very large thanks to the various people who guided me on the discord.

Techstack/layout/hardware:

1. Cloudflare domain with proxy active

2. Ubiquiti UDM Pro router

3. MS01 on Unbuntu, in default DMZ vlan

4. Client devices on other vlans(a secure VLAN, technically not the default but similar) or external to network

Personal skill level: I code for a living, but that's probably overstating my skill. Mostly light CRUD apps. Network is a MASSIVE blindspot that I know very little about. This project was in part to help fix that by getting me some practical experience. It's also GROSSLY overspecc'd for my skill level with some hope I can eventually do some more ambitious stuff.

Setup: I had installed Cosmos before and run it locally unsecured/self signed (as provided by just clicking on the button in cosmos), just to make sure I understood "intended" behavior.

My initial hiccups mostly revolved around me setting up port forwarding incorrectly in the router, so i'll skip most of that. Short version is misread something, went down the out of date documentation rabbit hole and then doubled down with some AI hallucinations. In the end it's MUCH easier than I was making it.

All i needed to do was setup a 443 port forward to the static IP of my Cosmos box. It's even limited to cloudflare IPs only, which was just taking the list provided by cloud flare and copy pasting it in. There's a section in ubiquitis network interface for this and it's very straight forward.

From there it was configuring the right tokens so I could do the cloudflare DNS Challenge, which is well documented (went the double token route rather than full key.) Once I found the right pages for that it was simple.

Made my tokens, but was confused as hell because in Comsos it says "you don't need to fill everything out" for cloudflare, and there's CLEARLY duplicate entries, so I wasn't sure if I needed to fill out both.

From what I can tell, you need to fill out the duplicates (so you will double enter your email and your key/tokens). You can leave blank things like timeouts or whatever you're not using (key if using tokens, token if using key). Some clarity on the dupe thing might help.

I do think a small guide on bare minimum DNS config would also help. I was using a root A record and a CNAME wildcard record, and I never got it to working with cosmos. Unsure if that's my fault or not, but when I changed the wildcard to another A record (so A record for root and A record for *), it started working. For someone like me who knows fuck all about any of this, there was a lot of stumbling around with DNS.

Of note I did select allow wildcard domains and .local domains on all attempts. No insecure http local access.

From there it, mostly, started working. Https enabled and everyone can connect....exceeeept .local domains.

This is the part i'm still struggling with. There's not a lot of documentation on .local, just "it will work if you check the box". I'm not sure if it clashes with https, or if i need to self sign, or if it really should be that easy.

My understanding is I just make new url for an app, call it whatever.local, and boom I should be able to connect so long as i'm one the same network.

In practice, I see no traffic hitting the server when I try this(unless on the server itself), and get timeouts from local clients (server does work). I got it to work once from a client on another vlan after trying to curl the https://whatever.local, but the next morning with nothing changed (went to bed right after and just left the machines running), it no longer worked.

I did 100% confirm this worked because I used filebrowser to transfer some large data at speeds that NEVER would have been possible if it wasn't over my local network(everything is wired, no wifi, hence the desire for .local access). Also worth noting that I CAN ping the server locally and ssh to it from my other network, so i'm confident the firewall/vlans are configured correctly for that.

Even for that brief moment when it was working, I STILL couldn't hit domain.local. It clearly exists, but if I can hit it (again from the server box or for that one moment from my other machine) I get the "you should use your domain address" text and cannot continue.

I suspect router shenanigans (i do have mdns enabled on all VLANS), but I'm having a hard time finding logs and what not for this. I'm also unsure if I don't know enough and am doing some config that obviously shouldn't work. I have toggled the "allow insecure local access" option in testing once or twice, but it doesn't seem to change anything. Not sure how long the delay should be.

Small things I noticed that might need fixing/expanding: 1. The initial admin account creation "your passwords do not match" help text is not in English. 2. Small thing but while browsing the market it seems there's a few configs that no longer work or aren't supported. EmulatorJS was the main one that seemed clearly done. 3. Hitting the domain, after logging in but not having touched it since forever, just gives you a "user unauthorized" warning but still lets you putter around the setup. 4. Related to that, it does sorta suck that right now even normal users see so much. I would like to hide a LOT of the interface for some of my users(just show them installed visible apps?), and while I can hide something like a new URL, I can't hide the URL screen, or the market, or whatever. It's "fine" but several test members had to be told "yes i know you can see that, no its fine, no you can't delete or edit, yes i know it looks like you can, yes i've tested, etc, etc" 5. In my testing, I did manage to get my domain IP banned by smart shield due to all the logging in and out. Was easy enough to bounce the box and get back in, but maybe a "heavy testing" mode an admin can enable that has smart shield chill for 30 minutes? Dunno how sane that is given the security first focus and I'm sure I could've whitelisted the IP briefly/neutered smart shield somewhere. 6. When entering your license key, you instantly see a "manage your license" button pop up. I emailed about it because I was confused and thought my license was busted, but just needed to scroll to the bottom and hit save. Just a flow thing that might wan to change. 7. Maybe an early "what is your goal" question? Local only vs using a domain vs using a domain and local access with adjusted config process to skip/auto handle things that could go wrong?
8. The "make admin only" checkbox on every app i've installed, that has it, doesn't appear to work. I have to go into the URL config and manually make it admin only from there. Maybe i'm misunderstanding where/how it's doing this, but some light testing seems to confirm that non admin accounts can access until I do that.

Side issues:

At some point in all this my Ubuntu took a spirited attempt at destroying itself and would let me login and then just show me a cursor and nothing else. Couldn't get to the terminal through the recommended ways, but after sshing to the box locally and changing uhh...the display driver I think?, it's mostly been working, but I cannot restart the machine without issues until I hard shutdown (hold the power button). I doubt this is related to cosmos (either caused by, or affecting behavior), but figure I should mention it just in case. Planning a full reinstall later.

Overall:

I do love it. Cosmos is trying to be something that I think should exist and yet for some reason does not. There's so many ways to screw something like this up and the "well just roll your own" approach is hellishly easy to screw up with extreme consequences. I have a few more upgrades/tweaks to do (get .local working, maybe reinstall the OS and the thus resetup from scratch, NAS for storage of some family videos/photos we want backed up in more than one spot), and I have mostly enjoyed how clear Cosmos has been.

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