How to Install Nix in an LXD Container

install_nix_in_an_lxd_container.md

How to Install Nix in an LXD Container

Steps to install the Nix package manager inside an Ubuntu 20.04 LXD container using the images:ubuntu/focal image:

1. On the LXD host, create an Ubuntu 20.04 container:

   lxc init images:ubuntu/focal container1
   

2. On the LXD host, enable nested security on the container:

   lxc config set container1 security.nesting true
   

3. Start the container:

   lxc start container1
   

4. Inside the container, install packages curl, gnupg2, man, rsync, and xz-utils:

   lxc exec container1 -- apt install --yes curl gnupg2 man-db rsync xz-utils
   

5. Inside the container, install Nix as user ubuntu because root may not perform a single-user Nix installation:

   lxc exec $container -- sudo --user ubuntu --login sh -c "curl --location --silent https://nixos.org/nix/install | sh"
   

install_nix_in_an_lxd_container.sh

#!/bin/sh

# Installs the Nix package manager (https://nixos.org/nix/) inside an LXD
# container.

#set -o xtrace

image=images:ubuntu/focal

if [ "$#" -eq 1 ]
then
  container=$1

  # Create a container from the given image and assign it the name from the
  # script argument.
  lxc init $image $container > /dev/null
else
  # Create a container from the given image and extract the random container
  # name that LXD assigns.
  container=`lxc init $image | grep "Instance name" | sed 's/^.* \(.*\)$/\1/'`
fi

echo "Created container $container."

# Enable nested security on the container.
# See https://github.com/NixOS/nix/issues/2649#issuecomment-518045796.
lxc config set $container security.nesting true

# Start the container.
lxc start $container

# Inside the container, install packages curl, gnupg2, man, rsync, and xz-utils.
lxc exec $container -- apt install --yes curl gnupg2 man-db rsync xz-utils

# Inside the container, install the Nix package manager as user "ubuntu".
# (see https://discuss.linuxcontainers.org/t/useful-lxc-command-aliases/2547/4)
# because root may not perform a single-user Nix installation
# (see https://github.com/NixOS/nix/issues/1559).
lxc exec $container -- sudo --user ubuntu --login sh -c "curl --location --silent https://nixos.org/nix/install | sh"

# Stop the container.
lxc stop $container

One could add xz-utils to the install job for Ubuntu 22.04 hosts.

Does the installation script fail on Ubuntu 22.04 containers?

Does the installation script fail on Ubuntu 22.04 containers?

Yes, the script does fail when it attempts to install Nix:

$ lxc exec witty-koi -- sudo --user ubuntu --login sh -c "curl --location --silent https://nixos.org/nix/install | sh"
sh: you do not have 'xz' installed, which I need to unpack the binary tarball

I added package xz-utils to the list of packages that the installation script installs inside the container.

Very well.