Bug [26.0.1, build d260a54] - Cannot access service about cli HOT 7 OPEN

Hello @robmry ,
well, I checked and I have no related logs inside the containers. The issue I am facing is that at random intervals the containers are not reachable from the LAN, the reverse proxy cannot reach them. Before version 26 I did not have any issue.
The issue involves IPv4 and Ubuntu 22.04.4. The firewall is disabled.
If you tell me what specific information you need I can provide it.

Thanks,
Michele

from cli.

This issue is not exclusive to @osinnowo as the problem hit me as well. I downgraded docker to the latest 25.0 release and all is well.

from cli.

Same here, I am having network issues accessing the containers after the upgrade to Docker version 26.0.1, build d260a54 on Ubuntu 22.04.4.

I can provide additional information if needed.

Thanks,
Michele

from cli.

Hi all - thank you for reporting. We'll need some more info to understand whether you're all seeing the same issue, and where the problem or problems are.

@osinnowo ... in the nginx example:

• Are you trying to access the web server from the docker host as http://127.0.0.1:8080, or different address or host? (Does the localhost address work?)
• Can you access the web server from the docker host, using the container's own address (from docker inspect) and port 80?
• Can you ping the nginx container's address from the docker host?
• Are you using a firewall, perhaps "ufw"?
• Are there any suspicious messages in the nginx container's log, or the docker engine logs?
• If you can share any logs, and output of docker container inspect, docker network inspect, ip a, iptables-save, iptables -nvL, iptables -t nat -nvL perhaps there will be a clue in there somewhere.
• (We might need to do some tcpdump-ing to see where packets are going missing.)

@tkimball83, @mdima - similar questions ... what does your environment look like, what commands are you using? Are you using IPv4 like @osinnowo, or IPv6 like @thomascrha? If you can share logs or other diagnostic info, that might help.

@thomascrha ... can you share any info about the IPv6 routing issues? How have you configured IPv6, what works from where etc? (Info as above, including ip6tables versions of the commands, might be useful.)

from cli.

Thanks @mdima - early versions of 25.0.x had an issue with containers getting duplicate MAC addresses, which caused intermittent connectivity - although I'd have expected that to cause problems in 25.0.x too. It might be worth checking docker container inspect output for duplicate MAC addresses anyway - deleting and re-creating the containers is the way to solve that problem.

Just to double-check, the failures are intermittent over the lifetime of a single container? (It's not that intermittently newly instantiated containers don't work?)

When there's an outage, and containers aren't accessible from the LAN - are they accessible from the docker host that's running them?

Which sort of networking are you using, are the containers on a custom bridge network (as they would be in the original post's compose/nginx example)?

If you're running multiple containers(?), do they all see the outage at the same time?

Which version did you upgrade to 26.0.1 from? Did you try reverting to a 25.0.x version, and did that help?

What sort of frequency/duration do the outages have? (If it works for a few seconds then fails for a few, that should be a bit easier to track down than a short failure in a long time.)

If possible, it'd be good to capture the output of the commands I mentioned above when it's working and when it's broken for comparison.

from cli.

Dear @robmry , yes, you're right. I inspected my containers and I found two MAC collisions (involving 4 containers in total).
Now I fixed them, I will wait for the next connectivity issue on the containers to follow your check-list.
In the while I can just say that I don't remember the version 25.0.x I upgraded from and I did not revert.

Thanks,
Michele

from cli.

Ah, great! Thank you for the update, hopefully that'll have solved the problem in your case.

from cli.