Nspawn Containers
This Link For Arch Linux Wiki for Nspawn Containers
Create a FileSystem
cd /var/lib/machines
# create a directory
mkdir <container>
# use pacstrap to create a file system
pacstrap -i -c -d <container> base --ignore linux
At this point you might want to copy over some configs to save time later.
- /etc/locale.conf
- /root/.bashrc
- /etc/locale.gen
First boot and create root password
systemd-nspawn -b -D <container>
passwd
poweroff
# if you want to nat the container add *-n* flag
systemd-nspawn -b -D <container> -n
# and to bind mount the package cache
systemd-nspawn -b -D <container> -n --bind=/var/cache/pacman/pkg
Networking
On Arch, assuming you have systemd-networkd and systemd-resolved
set up correctly, networking from the host end of things should
just work.
However on Linode it does not. What does work on Linode is to create
a bridge interface. Two files for br0 will get the job done.
# /etc/systemd/network/50-br0.netdev
[NetDev]
Name=br0
Kind=bridge
# /etc/systemd/network/50-br0.netdev
[Match]
Name=br0
[Network]
Address=10.0.55.1/24
DHCPServer=yes
IPMasquerade=yes
Notice how the configuration file tells systemd-networkd to offer
DHCP service and to perform masquerade. You can modify the systemd-nspawn
command to use the bridge interface. Every container attached to this bridge
will be on the same subnet and able to talk to each other.
# first restart systemd-networkd to bring up the new bridge interface
systemctl restart systemd-networkd
# and add --network-bridge=br0 to systemd-nspawn command
systemd-nspawn -b -D <container> --network-bridge=br0 --bind=/var/cache/pacman/pkg
Automatically Starting the Container
There are two ways to automate starting the container. You can override
systemd-nspawn@.service or create an nspawn file.
First enable machines.target
# to override the systemd-nspawn@.service file
cp /lib/systemd/system/systemd-nspawn@.service /etc/systemd/system/systemd-nspawn@<container>.service
Edit /etc/systemd/system/systemd-nspawn@<container>.service to add the systemd-nspawn options
you want to the ExecStart command.
Or create /etc/systemd/nspawn/<container>.nspawn
# /etc/systemd/nspawn/<container>.nspawn
[Files]
Bind=/var/cache/pacman/pkg
[Network]
Bridge=br0
# /etc/systemd/nspawn/<container>.nspawn
[Files]
Bind=/var/cache/pacman/pkg
[Network]
VirtualEthernet=1 # this seems to be the default sometimes, though
# in either case
systemctl start/enable systemd-nspawn@<container>
# to get a shell
machinectl shell <container>
# and then to get an environment
bash
Initial Configuration Inside The Container
# set time zone if you don't want UTC
timedatectl set-timezone <timezone>
# enable ntp, networktime
timedatectl set-ntp 1
# enable networking from inside the container
systemctl enable systemd-networkd
systemctl start systemd-networkd
systemctl enable systemd-resolved
systemctl start systemd-resolved
rm /etc/resolv.conf
ln -s /run/systemd/resolve/resolv.conf /etc/
# ping google
ping -c 3 google.com