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502 Bad Gateway Errors In HASS.io

That Dreaded 502 Bad Gateway Error

Okay. So this one drove me nuts for a long time, and when it came down to it, the fact that I couldn't solve the problem was due to the simple fact that I was missing a pretty obvious clue.

So, as of today, in my setup, I believe that I have solved the problem, but we'll see what happens in the future.

The Problem

After a fresh install of HASS.io on Ubuntu 18.04 in Docker, I was met with problems using add-ons that utilize Home Assistant's ingress feature.

Preface

If you aren't familiar with ingress (and I really don't 100% understand it either), it allows us to bypass the need for individual credentials for each add-on we install, and instead uses the core user credentials in Home Assistant to authenticate, open, and login to the add-on inside of the HASS.io user interface.

Many add-ons are simply third party apps that are already out there that require their own username and password to access. Add-ons like NodeRED, Portainer, ESPHome, etc.

With ingress, we should be able to simply open the WEB UI of each addon without needing to setup those credentials for each add-on.

502 Bad Gateway - NodeRED Primarily - But Others Too

A few of the add-ons that I installed in HASS.io failed to open. In fact, they would simply display a 502 Bad Gateway error. Naturally, this sounds like a networking error, but I was unsure why it was happening, and I didn't think at all to research firewall settings because I read somewhere that there shouldn't be any need for firewall adjustments due to how Docker networks work with Linux firewalls.

Alas, I was wrong. So, for a few months I've been pulling out my hair trying to figure out what is causing this. It wasn't until I spun up an entirely new Ubuntu box, installed HASS.io and NodeRED, and ran into the SAME problem that I concluded that it could be only one thing.

My Router.

Again I was wrong. The router is fine. It turns out that the firewall on my server(s), which is FirewallD, doesn't play nice with Docker. Now, at the root of it all, I still don't quite know what that means, or how to diagnose or fix that problem. But, I did figure out how to make the 502 Bad Gateway Error go away.

Steps to Solve

Note

Let it be known that I also use Webmin as my primary management interface for my Linux server, which makes it a bit easier to slide into the world of CLI management, but makes it a challenge to publish "how to" examples because I don't edit files directly much.

Assuming you're using HASS.io in Ubuntu with FirewallD and Docker, here's how I fixed the problem.

  1. In HASS.io, try to access the offending add-on to cause the 502 Bad Gateway error.
  2. From the HASS.io page in Home Assistant, click the System Tab.
  3. Make a note of the most recent error, which should be written in a red font color.

  4. In that error, you'll see an IP address and a port number.

    (This is where the embarrassing part is...since I did originally think it was a network problem, but completely overlooked the port number that was being accessed. Furthermore, I have an identical setup at my Church that didn't experience this problem, and it turns out the reason it didn't was because the port used was already open on the firewall.)

  5. In FirewallD, open that port.

  6. Apply your firewall settings.
  7. Restart HASS.io for good measure. I don't know if you really need to, but hey, I did.
  8. Access your WEB UI from that add-on that was throwing the 502 Bad Gateway error.

Did it work? Let me know.