Unusable application

joseph

@lanhild We have to debug this step by step.

Does host registry.cloudron.local resolve to public IP?
Check if nginx can reach the container.. docker ps | grep com.docker.registry to get container ID. docker inspect bea487bec441 | grep IPAddress to get local IP. curl http://172.18.20.34:5000/asdf -v should get some response for the registry. It will have Docker-Distribution-Api-Version header.
Then curl https://registry.cloudron.local ? This should give some UI page or login page of the registry

Depending on where it fails, we have to proceed. FWIW, docker login to same cloudron registry works fine on my servers.

Lanhild

@joseph My answers, step-by-step as you formatted it in your message:

Yes.
Reachable, Docker-Distribution-Api-Version: registry/2.0

<html>
<head><title>302 Found</title></head>
<body>
<center><h1>302 Found</h1></center>
<hr><center>nginx</center>
</body>
</html>

docker login from the Cloudron server results in the following

Error response from daemon: Get "https:/registry.cloudron.local/v2/": net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)

docker login from any other remote works perfectly fine.

Lanhild

I can't repro the issue on the demo server.

joseph

Out of ideas, since I can't reproduce this anywhere. You can contact me on support@ if you want me to debug on the server.

klawitterb

@joseph I've now also noticed problems with the docker registry. In my case I'm also running a builderbot on the same cloudron instance. Seems like it can't connect to the docker registry, my logs on the builderbot are simply saying:

Mar 28 08:42:05 build-1774683724218 Build stream finished
Mar 28 08:42:05 build-1774683724218 Pushing...
Mar 28 08:42:20 build-1774683724218 Push stream finished
Mar 28 08:42:20 build-1774683724218 Get "https://docker.apehost.de/v2/": net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
Mar 28 08:42:20 build-1774683724218 Push failed

Probably not related I've also noticed that the logs on the docker registry container get spammed with this error:

Mar 28 08:46:32 time="2026-03-28T07:46:32.467979729Z" level=error msg="traces export: Post \"https://localhost:4318/v1/traces\": dial tcp [::1]:4318: connect: connection refused" go.version=go1.23.7 instance.id=401bc88b-1bfe-4713-ae09-1cffdf628884 service=registry version=3.0.0
Mar 28 08:46:35 2026/03/28 07:46:35 [info] 71#71: *109 client 172.18.0.1 closed keepalive connection

Lanhild

@klawitterb said:
Probably not related I've also noticed that the logs on the docker registry container get spammed with this error:
Mar 28 08:46:32 time="2026-03-28T07:46:32.467979729Z" level=error msg="traces export: Post \"https://localhost:4318/v1/traces\": dial tcp [::1]:4318: connect: connection refused" go.version=go1.23.7 instance.id=401bc88b-1bfe-4713-ae09-1cffdf628884 service=registry version=3.0.0

I'm also encountering these.

robi

Assuming it is listening on port 4318, you can't do https with localhost.

Dropping the 's' should work if the API route is available.

girish

@Lanhild https://git.cloudron.io/packages/docker-registry-app/-/merge_requests/15 . I think that probably fixes it per upstream reports - https://github.com/distribution/distribution/issues/4270 , https://github.com/distribution/distribution-library-image/issues/187 . I don't think this related to your original DNS issue though. This traces export is just some log spam .

girish

OK, with the update that log message is gone (in our registry)

klawitterb

Log spam seems to be gone now, still having trouble with the actual connection to the registry on my cloudron:

Docker registry resides on the same cloudron

msbt

@klawitterb try without https://

klawitterb

Without https:// I'm getting: Invalid serverAddress: socket hang up

msbt

You got a typo in there maybe, or a firewall?

nebulon

So it should work without https:// there so the socket hang up is the issue somehow. Can you telnet via ssh to the registry from that server?

klawitterb

Just tried, that just gives me a telnet: Unable to connect to remote host: Connection refused

nebulon

If docker.apehost.de is the actual server, then I am able to contact that app from here at least. Does it correctly resolve on the system where it fails?

klawitterb

From the server:
ping -n docker.apehost.de -> works
telnet idontexist.apehost.de -> Name or service not known
telnet docker.apehost.de -> connection refused
docker pull docker.apehost.de/path-to-exisiting-image -> Error response from daemon: Get "https://docker.apehost.de/v2/": context deadline exceeded (Client.Timeout exceeded while awaiting headers)

From my local machine:
docker pull docker.apehost.de/path-to-exisiting-image -> works just fine

nebulon

So then telnet docker.apehost.de 443 also times out I assume. Is hairpin correctly working for you? run cloudron-support --troubleshoot to see this

klawitterb

Indeed seems like hairpin doesn't work, from troubleshoot:
[FAIL] Could not load dashboard domain.
Hairpin NAT is not working. Please check if your router supports it

I just tried the good old have you tried turning it off and on again, interestingly troubleshoot now errors with:
[FAIL] Could not load dashboard website with loopback check

klawitterb

So decided to upgrade my server to Ubuntu 24 and its working now again.

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