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 (something simple like '1234') 
for the root user.
"

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

# Target host details
#cd ~
#read -p "Enter hostname: " hostname
#read -p "Enter username: " username
#read -p "Enter ip address: " ip
#read -p "Enter nixosSystem to build, e.g. 'bootstrap': " config
hostname="bootstrap-nixos"
ip="192.168.122.192"
config="bootstrap"

# Generate key name and dir
HOST_KEY_DIR="$HOME/keys/hosts/$hostname"
mkdir -p "$HOST_KEY_DIR"

# Create ssh keys if not exists
echo "Creating '$hostname' ssh keys"
bash "/$HOME/nixos/scripts/generate_ssh_keys.sh" --type "host" --username "root" --hostname "$hostname"

# 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"

# Generate age key from target host and user public ssh key
echo "Generating age key from target host and user ssh key"
nix-shell -p ssh-to-age --run "cat $HOST_KEY_DIR/ssh_host_ed25519_key.pub | ssh-to-age > $HOST_KEY_DIR/age_host_key"
HOST_AGE_KEY=$(cat "$HOST_KEY_DIR/age_host_key")
echo -e "Host age key:\n$HOST_AGE_KEY\n"
echo "These keys needs to be inserted into .sops.yaml file. This will be prompted again later."

# Create temp directory for ssh keys to be copied to host:
temp=$(mktemp -d)

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

# Create the directory where sshd expects to find the host keys
install -d -m755 "$temp/persist/etc/ssh"

cat "$HOST_KEY_DIR/ssh_host_ed25519_key" > "$temp/persist/etc/ssh/ssh_host_ed25519_key" 
cat "$HOST_KEY_DIR/ssh_host_ed25519_key.pub" > "$temp/persist/etc/ssh/ssh_host_ed25519_key.pub" 

chmod 600 "$temp/persist/etc/ssh/ssh_host_ed25519_key"
chmod 644 "$temp/persist/etc/ssh/ssh_host_ed25519_key.pub"

# Install Nixos to target
cd "$HOME/nixos"
git add . && git commit -m "auto: bootstrapping $hostname" && git push
[ $? != 0 ] && echo "Error commiting current changes" && exit 1

SHELL=/bin/sh nix run github:nix-community/nixos-anywhere -- --extra-files "$temp" --flake .#"$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

# Check host OS has booted (and not booted back into live cd)
while true;
do
  read -p "Confirm live CD has been removed... (yes|no): " confirm
  [ "$confirm" = "yes" ] && break
done
echo "Waiting for $ip to come back online and port 22 to be open..."
while ! ping -c 1 $ip &> /dev/null || ! nc -zvw3 $ip 22 &> /dev/null
do
    echo "$ip is still offline or port 22 is not open. Checking again in 5 seconds..."
    sleep 5
done
echo "$ip is now online and port 22 is open!"

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

# Copy deploy_key to target for personal repo authorisation
scp -i "$(readlink -f "$HOME/.ssh/id_ed25519")" "$(readlink -f "$HOME/.ssh/deploy_key-ssh-ed25519")" "root@$ip:/persist/etc/ssh/deploy_key-ssh-ed25519"

echo -e "
Complete!

Now add the new target host age key to .sops.yaml. This is needed to enable the
new host to decrypt the secrets.yaml file from the ssh key we generated
previously.

Enter the details as following:
keys:
- &hosts:
    - &$hostname $HOST_AGE_KEY

creation_rules:
  - path_regex: secrets.yaml$
    key_groups:
      - age:
        - *$hostname

Then update (i.e. re-encrypt) the secrets.yaml file with the new keys, run:

  'sops --config .sops.yaml updatekeys secrets.yaml' 

or with just:

  'just update-sops-secrets'

Then commit and push these changes to remote so they can be accessed on the new
host.
"

while true;
do
  read -p "Confirm keys have been added to .sops.yaml using the above steps, and the changes (if any) have been commited and pushed...(yes|no): " confirm
  [ "$confirm" = "yes" ] && break
done

ssh -i "$(readlink -f "$HOME/.ssh/id_ed25519")" "root@$ip" "nix-shell -p git --run 'git clone git@git.bitlab21.com:sam/nixos.git /persist/etc/nixos/'"

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

exit 0