Lost hostname resolution on Ubuntu Docker 16.04

I don’t know what happened… I lost DNS resolution on my Ubuntu Docker 16.04 DO droplet.

root@gpc-docker-sfo2:resolvconf$ telnet 443
telnet: could not resolve Temporary failure in name resolution
root@gpc-docker-sfo2:resolvconf$ cat /etc/resolv.conf 

I don’t know what happened? How do I get this back working?

(Ubuntu Docker 1.12.5 on 16.04)

As a note: I’ve always kept my apps updated via apt-get. Was there something related to the recent Docker 13.0 update?


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I fixed it!

Well. I don’t know what happened: looks like something went amiss when I added IPv6 to this image (post-create) through the console.

I creating a new image (IPv6 on create) in attempts to replicate. I found two differences in the new image:

  • It had IPv6 settings within interfaces.d/50-cloud-init.cfg
  • It didn’t have ubuntu-fan files within the if-[up/down].d/ directories

So, I added IPv6 settings and removed the ubuntu-fan files.

Rebooted the box, and we’re back working!

Any idea what the ubuntu-fan files are for? Are they necessary?