Quick solve

Introduction

This is a selection of problems that can be quickly solved.

Docker

Auto-start instances

docker update --restart=always <container_name>

Ubuntu

Too many network interfaces

If the following appears in /var/log/syslog:

avahi-daemon[1113]: IP_ADD_MEMBERSHIP failed: No buffer space available

It's probably because you've too many network interfaces. This can easily happen with docker. You can check your current configured maximum using this:

sysctl net.ipv4.igmp_max_memberships

You can increase that amount using the following command:

sysctl -w net.ipv4.igmp_max_memberships=50