Incorrect syntax in LXC user config file to create unprivileged containers

[Eric Newberry]

In the 18.04 Server Guide, the reader is told to create a file at ~/.config/lxc/default.conf containing the following values (with their equivalent subuid and subgid values) to allow the use of unprivileged containers:

lxc.id_map = u 0 100000 65536
lxc.id_map = g 0 100000 65536
lxc.network.type = veth
lxc.network.link = lxcbr0

However, when I attempt to run this (with a higher log level than default), LXC outputs syntax errors. After a quick search online, it appears that the correct configuration key is "lxc.idmap" instead of "lxc.id_map". Additionally, after correcting this issue, I also received another error message about the network configuration in ~/.config/lxc/default.conf. The official LXC documentation (https://linuxcontainers.org/lxc/getting-started/) states to copy the config file from /etc/lxc/default.conf and use it as a base for the user default.conf, appending the "lxc.idmap" values. This original file on my system contained the following lines, as opposed to the network configuration lines in the Server Guide's suggested configuration:

lxc.net.0.type = veth
lxc.net.0.link = lxcbr0
lxc.net.0.flags = up
lxc.net.0.hwaddr = 00:16:3e:xx:xx:xx

After doing the above steps, unprivileged LXC contains can now be created on my system. I am running Ubuntu 18.04 with the latest lxc version from apt (3.0.1-0ubuntu1~18.04.1).