DNS resolution is not available (Ubuntu 18.04.1)

Expected Behaviour:

After installing on a fresh Ubuntu 18.04.1 LXC container, which is the only uncommon aspect of this install, the installer should report DNS resolution is available.

Actual Behaviour:

The installer reports that DNS resolution is not available. Calling 'pihole status' also reports the DNS resolution is not available.

Debug Token:

zuilm1vtrl

I have another Pi-hole install running under a container on Ubuntu 16.04 LTS. When I updated it this morning I got the same behaviour as when installing it under 18.04.

These related threads may be of assistance:

The third link (Installed Pi-hole but No DNS Resolution (Ubuntu 18.04.1)) sort of helped.

Here is what I get:

root@pihole2:~# service pihole-FTL status
● pihole-FTL.service - LSB: pihole-FTL daemon
Loaded: loaded (/etc/init.d/pihole-FTL; generated)
Active: active (exited) since Mon 2018-10-08 21:51:59 UTC; 4s ago
Docs: man:systemd-sysv-generator(8)
Process: 8526 ExecStop=/etc/init.d/pihole-FTL stop (code=exited, status=0/SUCCESS)
Process: 8530 ExecStart=/etc/init.d/pihole-FTL start (code=exited, status=0/SUCCESS)

Oct 08 21:51:59 pihole2 pihole-FTL[8530]: Not running
Oct 08 21:51:59 pihole2 pihole-FTL[8530]: chown: cannot access '/etc/pihole/dhcp.leases': No such file or directory
Oct 08 21:51:59 pihole2 pihole-FTL[8530]: Failed to set capabilities on file `/usr/bin/pihole-FTL' (Operation not permitted)
Oct 08 21:51:59 pihole2 pihole-FTL[8530]: The value of the capability argument is not permitted for a file. Or the file is not a regular (non-symlink) file
Oct 08 21:51:59 pihole2 su[8553]: Successful su for pihole by root
Oct 08 21:51:59 pihole2 su[8553]: + ??? root:pihole
Oct 08 21:51:59 pihole2 su[8553]: pam_unix(su:session): session opened for user pihole by (uid=0)
Oct 08 21:51:59 pihole2 pihole-FTL[8530]: dnsmasq: failed to create listening socket for 192.168.1.3: Permission denied
Oct 08 21:51:59 pihole2 su[8553]: pam_unix(su:session): session closed for user pihole
Oct 08 21:51:59 pihole2 systemd[1]: Started LSB: pihole-FTL daemon.

It looks like restarting pihole-FTL is having problems setting capabilities on /usr/bin/pihole-FTL.

Ok. That worked.

After changing the line in /etc/init.d/pihole-FTL from:

su -s /bin/sh -c "/usr/bin/pihole-FTL" "$FTLUSER"

to:

/usr/bin/pihole-FTL

then doing a:

sudo systemctl daemon-reload

and finally a:

sudo service pihole-FTL restart

the result of a pihole status becomes:

[✓] DNS service is running
[✓] Pi-hole blocking is Enabled

So that's something.

But is Ubuntu under LXC, or Ubuntu 16.04 to 18.04 considered a supported target? If it is, it is a piece of cake for me to test any possible solutions.

As of now, Ubuntu 16.04 and 16.10 are the officially supported versions. There are users running on 18.04, many with problems similar to what you are seeing.

https://docs.pi-hole.net/main/prerequesites/

Is your Pi-Hole working properly now? If you like, upload a debug log and we'll look at it.

I had the same symptoms under Ubuntu 16.04, also under LXC. I just deleted the container, so I can't be sure that the fix would have worked with it too.

Yes, my Pi-Hole container is working fine. The issue can be closed, but I'm happy to help with the larger issue if I can.

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