bootstrap-nix

#!/usr/bin/env bash

# Config
HOME=$(realpath "$HOME") # Yeah, I don't know why argon does this
nix_version="2.23"
nix_url="https://hydra.nixos.org/job/nix/maintenance-${nix_version}/buildStatic.x86_64-linux/latest/download-by-type/file/binary-dist"
nix_location="$HOME/.local/bin"
bash_profile="$HOME/.bashrc"
bash_dir="$HOME/.bashrc.d"
bashrc_fragment="$bash_dir/nix.bash"
nix_exe="${nix_location}/nix"
nix_conf_home="${XDG_CONFIG_HOME:-$HOME/.config}"/nix

# Run

cat << EOF
This script will install nix locally, it was designed to be minimally invasive.
It will, however, make a couple of changes to your environment.

1) It will download the official nix executeable into $nix_location
2) It will modify your bashrc $bash_profile so nix is discoverable
3) It will add git to your default module set
4) It will add a monthly cron job to cleanup leftover nix data

EOF

read -p "Would you like to continue (y/n)? " -n 1 -r choice

case "$choice" in
	y|Y ) ;;
	* ) echo "Aborting" && exit 1;;
esac
echo

# Download nix
download_nix() {
	nix_exe=$(realpath "$nix_exe")
	mkdir -p "$nix_location"
	echo "Downloading nix to $nix_exe"
	curl -L "$nix_url" -o "$nix_exe"
	chmod +x "$nix_exe"
}

download_nix

# Modify bashrc
echo "Modifying bashrc"

mkdir -p "$bash_dir"
cat << 'EOF' > "$bashrc_fragment"
# This will add a directory to a path if its not already there
pathadd() {
    if [ -d "$1" ] && [[ ":$PATH:" != *":$1:"* ]]; then
        PATH="${PATH:+"$PATH:"}$1"
    fi
}

# Home should not be a symlink, I'm not really sure why it is one
HOME=$(realpath "$HOME")

# Nix needs to know where this is
export NIX_SSL_CERT_FILE=/etc/ssl/certs/ca-bundle.crt

# Add .local/bin to the path
pathadd "$HOME/.local/bin"
EOF

grep -q "$bashrc_fragment" "$bash_profile" || {
	cat <<- EOF >> "$bash_profile"
	
	# Load nix
	. "$bashrc_fragment"
	EOF
}

# Modify module set
echo "Loading git module"
module load git
echo "Saving current module set"
module save

# Configure nix
mkdir -p "$nix_conf_home"
nix_conf="$nix_conf_home"/nix.conf
grep -q "experimental-features" "$nix_conf" || cat "experimental-features = nix-command flakes" >> "$nix_conf"
grep -q "sandbox = false" "$nix_conf" || cat "sandbox = false" >> "$nix_conf"

link_to_nix() {
	ln -s "${nix_location}/nix" "${nix_location}/${1}"
}

link_to_nix "nix-build"
link_to_nix "nix-channel"
link_to_nix "nix-collect-garbage"
link_to_nix "nix-copy-closure"
link_to_nix "nix-env"
link_to_nix "nix-hash"
link_to_nix "nix-instantiate"
link_to_nix "nix-prefetch-url"
link_to_nix "nix-shell"
link_to_nix "nix-store"

# Setup cronjob
echo "Configuring cronjob"
cron_cmd="HOME=$HOME $HOME/.local/bin/nix-collect-garbage"
cron_job="@monthly $cron_cmd"
( crontab -l | grep -v -F "$cron_cmd" || : ; echo "$cron_job") | crontab -

# Check
echo "Initial run of nix to make sure everthing works, this may take a second..."
$nix_exe run nixpkgs#cowsay -- "All done! You probably have to re-login or run \`. ~/.bashrc\`"