nixos/scripts/bootstrap.sh

#!/usr/bin/env bash

echo -e "
Before using this tool, ensure that the host has been setup correctly.
Boot the latest Nixos-minimal install ISO on the host and access the tty.

Use 'ip a' to get the ip address, then 'sudo su' to change to root. Finally Run
'passwd' and set a temporary password for the root user.

Also, ensure secrets for the new host and users have been set in secrets.yaml
"

read -p "Confirm host had been setup using the above steps...(yes|no): " confirm
[ "$confirm" != "yes" ] && echo "Exiting" && exit 0

read -p "Enter hostname of target: " hostname
read -p "Enter IP of target: " ip
read -p "Enter config to install on target: " config
read -p "Enter username (if none, use 'root'): " username
read -p "Using impermanence? (yes|no): " impermanence 
[ "$impermanence" = "yes" ] && persist="/persist"

# Delete key in known hosts if exists
sed -i "/$ip/d" ~/.ssh/known_hosts

# Authorise source public key
echo "Copying pubkey to target host"
ssh-copy-id -i "$(readlink -f "$HOME/.ssh/id_ed25519.pub")" "root@$ip"

# Create temp directory for ssh and luks keys to be copied to host:
temp=$(mktemp -d)
touch /tmp/luks_secret.key

# Function to cleanup temporary directory on exit
cleanup() {
  rm -rf "$temp" /tmp/luks_secret.key
}
trap cleanup EXIT

# Create the directory for target host keys
install -d -m755 "$temp$persist/etc/ssh"

# Create ssh keys
echo "Creating '$hostname' ssh keys"
ssh-keygen -t ed25519 -f "$temp$persist/etc/ssh/ssh_host_ed25519_key" -C root@"$hostname" -N ""

# Extract luks key from secrets
luks_secret=$(nix-shell -p sops --run "SOPS_AGE_KEY_FILE=~/.config/sops/age/keys.txt sops -d --extract '[""\"luks_passphrase""\"][""\"$hostname""\"]' ../nix-secrets/secrets.yaml")
echo "$luks_secret" > /tmp/luks_secret.key

# Generate age key from target host and user public ssh key
echo "Generating age key from target host and user ssh key"
HOST_AGE_KEY=$(nix-shell -p ssh-to-age --run "cat $temp$persist/etc/ssh/ssh_host_ed25519_key.pub | ssh-to-age")
echo -e "Host age key:\n$HOST_AGE_KEY\n"

# Update .sops.yaml with new age key:
SOPS_FILE="../nix-secrets/.sops.yaml"
sed -i "{
# Remove any * and & entries for this host
/[*&]$hostname/ d;
# Inject a new age: entry
# n matches the first line following age: and p prints it, then we transform it while reusing the spacing
/age:/{n; p; s/\(.*- \*\).*/\1$hostname/};
# Inject a new hosts: entry
/&hosts:/{n; p; s/\(.*- &\).*/\1$hostname $HOST_AGE_KEY/}
}" $SOPS_FILE

# Commit and push changes to sops file
just update-sops-secrets && just update-flake-secrets && just update-flake

# Copy current nix config over to target
cp -prv . "$temp$persist/etc/nixos"

# Install Nixos to target
SHELL=/bin/sh nix run github:nix-community/nixos-anywhere/1.3.0 -- --extra-files "$temp" --disk-encryption-keys /tmp/luks_secret.key /tmp/luks_secret.key --flake .#"$config" root@"$ip" -i "$HOME/.ssh/id_ed25519"
[ $? != 0 ] && echo "Error installing Nixos" && exit 1

## Delete keys from local known_hosts
echo "Deleting host from known_hosts"
sed -i "/$ip/d" ~/.ssh/known_hosts

echo -e "###\nSuccessfully installed Nixos on the target host!\n###"

exit 0