Hi, In the last days we started suddenly having an issue with sending emails… then we’ve tried to upgrade/update without success (the update page hangs and every component - docker, discourse, plugins - get stuck at “Checking for new version…”) and then we tried to update everything via root but the rebuild fails giving the following message (among other things): fatal: unable to access 'https://github.com/discourse/discourse.git/': Could not resolve host: github.com` Our host has confirmed that there are no problems with the server connectivity, SSL, firewall or any other thing. I suspect is something with docker. Even checked this topic: Docker sometimes fails to connect to github.com - Installation - Discourse Meta and tried: # cd /var/discourse/ # ./launcher enter app # wget -O - -v https://github.com/discourse/logster.git/ |wc and got the following: --2025-02-28 09:45:51-- https://github.com/discourse/logster.git Resolving github.com (github.com)... failed: Temporary failure in name resolution. wget: unable to resolve host address ‘github.com’ 0 0 0 Any ideas on how to address this issue?

I’m just posting to update on the situation. It got solved with help from ChatGPT. After trying different solutions, this part showed that something was wrong with the permissions or security policies: Try Running a Container with the --privileged Flag This bypasses some restrictions that might be affecting networking. docker run --rm --privileged alpine ping -c 4 github.com If this works, it suggests a permissions or security policy issue. After that, applied the next suggestion: Check iptables Rules Again Since Docker relies on iptables, let’s confirm it has the correct forwarding rules. Run: sudo iptables -t nat -L -v -n | grep -i docker If no Docker-related rules appear, manually add them: sudo iptables -P FORWARD ACCEPT sudo iptables -A FORWARD -i docker0 -o eth0 -j ACCEPT sudo iptables -t nat -A POSTROUTING -s 172.17.0.0/16 ! -o docker0 -j MASQUERADE Then restart Docker: sudo systemctl restart docker And test again. … which totally did it. :grin:

Are you operating in a special territory such as mainland China? I would check DNS on your host and then check DNS in your docker. check DNS on your host: resolvectl status|egrep Servers nslookup github.com check DNS in your docker docker exec -it app bash -c "cat /etc/resolv.conf" docker exec -it app bash -c "wget -O - -v https://github.com/discourse/logster.git/ |wc"

Ok, so: on host DNS: #resolvectl status|egrep Servers DNS Servers: 8.8.8.8 Fallback DNS Servers: 8.8.8.8 DNS Servers: 8.8.8.8 8.8.4.4 #nslookup github.com Server: 8.8.8.8 Address: 8.8.8.8#53 Non-authoritative answer: Name: github.com Address: 140.82.112.3 On Docker DNS: #docker exec -it app bash -c "cat /etc/resolv.conf" # Generated by Docker Engine. # This file can be edited; Docker Engine will not make further changes once it # has been modified. nameserver 8.8.8.8 nameserver 8.8.4.4 # Based on host file: '/etc/resolv.conf' (legacy) # Overrides: [nameservers] #docker exec -it app bash -c "wget -O - -v https://github.com/discourse/logster.git/ |wc" --2025-02-28 12:20:17-- https://github.com/discourse/logster.git/ Resolving github.com (github.com)... failed: Temporary failure in name resolution. wget: unable to resolve host address ‘github.com’ 0 0 0 P.S: Our host operates in Canada.

Thanks… I have no idea how this might happen, but I’m not a docker expert. What’s your host OS, and how did you install Discourse? Did you use a package supplied by the hosting company, or is it a standard install? (Or a dev install??) How did you install Docker? But this all used to work, and then stopped working, so possibly it is docker related. Perhaps you can update your docker installation??

It’s a standard install that have been working very well so far in AlmaLinux in the past few months (and before that well too in CentOS). How can I update the docker installation (without the usual rebuild instruction with launcher or the through the website as none of these methods seem to be working)?

Before you go any further, please take a backup (if you can) and download a local copy. (Perhaps try Move a Discourse site to another VPS with rsync) Please try these, they might give a hint: docker --version docker run hello-world

With a bit of help from ChatGPT I found that it is the Docker’s Bridge network configuration or whatever that means that is the problem. I’ve tried several fixes but so far without success. Haven’t tried this one yet: [The image provides steps to manually reset Docker networking by stopping Docker, deleting the network directory, and restarting Docker. (Captioned by AI)] Is this safe for a production environment? (even if it creates a short downtime)

I’m afraid I don’t know. I trust you have a safe recent backup. The least disruptive thing to do might be a reboot.

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Produktunterstützung

Ed_S (Ed S) 28. Februar 2025 um 21:06 8

Ich fürchte, ich weiß es nicht. Ich vertraue darauf, dass du eine sichere aktuelle Sicherung hast. Das Weniger störende Vorgehen könnte ein Neustart sein.

Thema		Antworten	Aufrufe
After upgrade, docker cannot communicate with the outside world Self-hosting	26	3897	1. Februar 2021
./discourse-setup: could not resolve host: github.com Product Support	5	2867	3. Januar 2021
Discourse docker container has trouble reaching DNS Self-hosting	10	4584	30. April 2018
Docker sometimes fails to connect to github.com Self-hosting	8	4666	5. Januar 2023
Could not resolve host: github.com for SamSaffron/pups.git Product Support docker	11	12099	12. November 2020

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