cannot install redis-server on ubuntu 18.04

Question

I have upgraded to ubuntu 18.04 from 17.10. The redis-server package cannot be fully installed. I looked at /var/log/syslog and it says

==> /var/log/syslog <==
Jun  3 13:04:10 qaz-mko systemd[1]: redis-server.service: Can't open PID file /var/run/redis/redis-server.pid (yet?) after start: No such file or directory
Jun  3 13:05:01 qaz-mko CRON[3429]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Jun  3 13:05:40 qaz-mko systemd[1]: redis-server.service: Start operation timed out. Terminating.
Jun  3 13:05:40 qaz-mko systemd[1]: redis-server.service: Failed with result 'timeout'.
Jun  3 13:05:40 qaz-mko systemd[1]: Failed to start Advanced key-value store.
Jun  3 13:05:40 qaz-mko systemd[1]: redis-server.service: Service hold-off time over, scheduling restart.
Jun  3 13:05:40 qaz-mko systemd[1]: redis-server.service: Scheduled restart job, restart counter is at 13.
Jun  3 13:05:40 qaz-mko systemd[1]: Stopped Advanced key-value store.
Jun  3 13:05:40 qaz-mko systemd[1]: Starting Advanced key-value store...
Jun  3 13:05:40 qaz-mko systemd[1]: redis-server.service: Can't open PID file /var/run/redis/redis-server.pid (yet?) after start: No such file or directory

==> /var/log/redis/redis-server.log <==
3416:C 03 Jun 13:02:39.637 # Configuration loaded
3417:M 03 Jun 13:02:39.639 # Creating Server TCP listening socket ::1:6379: bind: Cannot assign requested address
3423:C 03 Jun 13:04:10.121 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
3423:C 03 Jun 13:04:10.121 # Redis version=4.0.9, bits=64, commit=00000000, modified=0, pid=3423, just started
3423:C 03 Jun 13:04:10.122 # Configuration loaded
3424:M 03 Jun 13:04:10.124 # Creating Server TCP listening socket ::1:6379: bind: Cannot assign requested address
3435:C 03 Jun 13:05:40.602 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
3435:C 03 Jun 13:05:40.602 # Redis version=4.0.9, bits=64, commit=00000000, modified=0, pid=3435, just started
3435:C 03 Jun 13:05:40.602 # Configuration loaded
3436:M 03 Jun 13:05:40.604 # Creating Server TCP listening socket ::1:6379: bind: Cannot assign requested address

However then it times out and does not start the redis deamon. The config file is the one that came with the package.

Do you want to continue? [Y/n] Y
Setting up redis-server (5:4.0.9-1) ...
Job for redis-server.service failed because a timeout was exceeded.
See "systemctl status redis-server.service" and "journalctl -xe" for details.
invoke-rc.d: initscript redis-server, action "start" failed.
● redis-server.service - Advanced key-value store
   Loaded: loaded (/lib/systemd/system/redis-server.service; disabled; vendor preset: enabled)
   Active: activating (auto-restart) (Result: timeout) since Sun 2018-06-03 12:47:34 EDT; 14ms ago
     Docs: http://redis.io/documentation,
           man:redis-server(1)
  Process: 2156 ExecStart=/usr/bin/redis-server /etc/redis/redis.conf (code=exited, status=0/SUCCESS)
dpkg: error processing package redis-server (--configure):
 installed redis-server package post-installation script subprocess returned error exit status 1
dpkg: dependency problems prevent configuration of redis:
 redis depends on redis-server (<< 5:4.0.9-1.1~); however:
  Package redis-server is not configured yet.
 redis depends on redis-server (>= 5:4.0.9-1); however:
  Package redis-server is not configured yet.

dpkg: error processing package redis (--configure):
 dependency problems - leaving unconfigured
No apport report written because the error message indicates its a followup error from a previous failure.
                                                                                                          Errors were encountered while processing:
 redis-server
 redis
E: Sub-process /usr/bin/dpkg returned an error code (1)

I have tried creating the pid file by hand and giving it lots of permissions. But that does not seem to work.

sudo touch /var/run/redis/redis-server.pid
# sudo chown redis:redis /var/run/redis/redis-server.pid
# sudo chmod 777 /var/run/redis/redis-server.pid
# sudo ls -alh /var/run/redis/
total 0
drwxr-sr-x  2 redis redis  60 Jun  3 12:54 .
drwxr-xr-x 33 root  root  940 Jun  3 12:53 ..
-rwxrwxrwx  1 redis redis   0 Jun  3 12:54 redis-server.pid

Answer 1

It is possible to get redis-server running even when IPv6 is disabled.

Simply remove the ::1 IPv6 loopback address from the bind config option (by default located in /etc/redis/redis.conf):

- bind 127.0.0.1 ::1
+ bind 127.0.0.1

Now redis will not try to use the IPv6 network.