Installing Nix in WSL (Ubuntu)

Attempting to install nix while in WSL returns some obtuse errors.

Missing cgroups support

The Nix sandbox relies on container functionality that Windows has yet to implement in the WSL abstraction layer. If you do not disable the sandbox the follow error occurs.

error: cloning builder process: Invalid argument
error: unable to start build process

Incorrect file locking

The lock handling in Windows NT doesn’t perfectly match Linux’s. While SQLite works fine under the Win32 personality, it produces deadlocks when you try to install Nix, producing this infinite warning loop:

warning: SQLite database '/nix/var/nix/db/db.sqlite' is busy (SQLITE_PROTOCOL)
warning: SQLite database '/nix/var/nix/db/db.sqlite' is busy (SQLITE_PROTOCOL)
warning: SQLite database '/nix/var/nix/db/db.sqlite' is busy (SQLITE_PROTOCOL)
warning: SQLite database '/nix/var/nix/db/db.sqlite' is busy (SQLITE_PROTOCOL)
warning: SQLite database '/nix/var/nix/db/db.sqlite' is busy (SQLITE_PROTOCOL)

Installing Nix

Adding the following to /etc/nix/nix.conf before installing nix allows for workarounds the allow a successful installation.

mkdir -p /etc/nix/
cat << EOF > /etc/nix/nix.conf
# Work around missing cgroups support
# https://github.com/Microsoft/WSL/issues/994
sandbox = false

# Work around incorrect file locking
# https://github.com/Microsoft/WSL/issues/2395
use-sqlite-wal = false
EOF

Now Run the Nix Package Manager Install script and you will have a successful install.