setup shadowsocks server for my vps

vps_setup.sh

#!/usr/bin/env bash

# change the working directory to where this file is located
full_file_path=`realpath $0`
absolute_dir=`dirname $full_file_path`
cd $absolute_dir

# crate new user if not exists
username="bot"
userpassword="password123456"

# shadowsocks server config
server_port="6666"
password="123456"
method="chacha20-ietf-poly1305"


if ! id -u $username >/dev/null 2>&1; then

    sudo useradd -m -s /bin/bash -U -p `openssl passwd -1 $userpassword` $username
    echo "$username ALL=(ALL:ALL) NOPASSWD:ALL" | sudo bash -c "cat > /etc/sudoers.d/$username"
    sudo chmod 0440 /etc/sudoers.d/$username
    sudo -u $username mkdir -p /home/$username/.ssh
    sudo cp ~/.ssh/authorized_keys /home/$username/.ssh/authorized_keys
    sudo chown $username:$username /home/$username/.ssh/authorized_keys

    sudo sed -i "s/.*PasswordAuthentication.*yes.*/PasswordAuthentication no/" /etc/ssh/sshd_config
    sudo systemctl restart sshd

fi


if ! which snap >/dev/null 2>&1; then
    sudo apt update
    sudo apt -y install build-essential

    sudo apt install snapd -y
fi


if ! snap services shadowsocks-rust.ssserver-daemon >/dev/null 2>&1; then

    sudo snap install shadowsocks-rust
    sudo mkdir -p /var/snap/shadowsocks-rust/common/etc/shadowsocks-rust
fi

json=`cat << EndOfMessage
{
    "server": "0.0.0.0",
    "server_port": $server_port,
    "password": "$password",
    "method": "$method",
    "mode":"tcp_and_udp"
}
EndOfMessage
`
echo $json | sudo bash -c "cat > /var/snap/shadowsocks-rust/common/etc/shadowsocks-rust/config.json"


if [ `snap services shadowsocks-rust.ssserver-daemon | awk 'NR > 1 {print $3}'` != "active" ]; then
    sudo snap start --enable shadowsocks-rust.ssserver-daemon
    # sudo snap logs shadowsocks-rust
fi

sleep 2

if [ `snap services shadowsocks-rust.ssserver-daemon | awk 'NR > 1 {print $3}'` = "active" ]; then
    exit 0
fi


############## If the snap does not work, we will install our own shadowsocks-rust  ##############
printf "snap start shadowsocks-rust.ssserver-daemon failed.\n"
while true; do
    read -p "Do you wish to try cargo install shadowsocks-rust? " yn
    case $yn in
        [Yy]* ) break;;
        [Nn]* ) exit;;
        * ) echo "Please answer yes or no.";;
    esac
done

if ! which cargo >/dev/null 2>&1; then
    sudo apt update
    sudo apt -y install build-essential # binutils-dev libunwind-dev libblocksruntime-dev liblzma-dev

    # https://unix.stackexchange.com/questions/491090/how-to-set-parameters-when-pipe-bash-script-to-bash
    curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
    source "$HOME/.cargo/env"
fi

if ! which ssserver >/dev/null 2>&1; then
    cargo install shadowsocks-rust
fi

ssserver -d -c /var/snap/shadowsocks-rust/common/etc/shadowsocks-rust/config.json



# EOF