run: ansible-playbook -i new-server.ini new-server-setup-ubuntu-22.yaml, node_exporter.service.j2 should be placed in templates directory

new-server.ini

[servers]
YOUR-IP

[all:vars]
ansible_ssh_common_args='-o StrictHostKeyChecking=no'
ansible_python_interpreter='/usr/bin/python3'
prometheus_source_ip='PROMETHEUS-IP'
systemd_path='/etc/systemd/system'
default_ssh_user='ubuntu'
default_ssh_port='22'
sshd_config_port='12345'
prometheus_port='9100'
node_exporter_version='1.4.0'
go_arch='amd64'
_node_exporter_binary_install_dir='/usr/local/bin'

node_exporter.service.j2

[Unit]
Description=Node Exporter
After=network.target
 
[Service]
Type=simple
ExecStart=/usr/local/bin/node_exporter
 
[Install]
WantedBy=multi-user.target

ovh-new-server-setup-ubuntu-22.yaml

---
- hosts: all
  become: yes
  vars:
    ansible_ssh_user: '{{ default_ssh_user }}'
    ansible_ssh_port: '{{ default_ssh_port }}'
    sudo_user:
       # password must be generated through "mkpasswd" command from 'whois' package
      - login: '{{ ansible_user }}'
        group: '{{ ansible_user }}'

  tasks:
### AGX1000 scripts ###
    - name: Download hwdata.sh
      get_url:
        url: https://gist.githubusercontent.com/AGx10k/bebd6297c7d8a8bd856a55ad2f2393a5/raw/b42b5d9d3edc2c9be1fe36d1518f4a68eb46f2ad/hwdata.sh
        dest: /root/hwdata.sh
        mode: 'u+rwx'

    - name: Download netdata.sh
      get_url:
        url: https://gist.githubusercontent.com/AGx10k/bebd6297c7d8a8bd856a55ad2f2393a5/raw/c72fe59642c34622b8014a4888bcf9734197815c/netdata.sh
        dest: /root/hwdata.sh
        mode: 'u+rwx'

    - name: Adding the scripts in the profile file
      lineinfile: 
        dest: '~/.profile'
        line: '~/hwdata.sh && ~/netdata.sh'
        insertafter: 'EOF' 
        state: present

    - name: export env vars
      shell: "export DEBIAN_FRONTEND=noninteractive"

### install packages ###
    - name: Install required system packages
      apt: 
        name: ['cpufrequtils', 'moreutils', 'ntp', 'iptables-persistent', 'software-properties-common', 'aptitude', 'git', 'curl', 'lm-sensors','moreutils', 'cpufrequtils', 'liblz4-tool', 'zip', 'unzip', 'jq', 'wget', 'nano', 'htop', 'smartmontools', 'tmux', 'net-tools', 'bash-completion', 'pciutils', 'ethtool', 'ufw', 'mc', 'python3', 'python3-dev', 'python3-virtualenv', 'python3-venv', 'python3-dev', 'libffi-dev', 'apt-transport-https', 'tzdata', 'ca-certificates', 'build-essential', 'libboost-all-dev', 'automake', 'autoconf', 'pkg-config', 'libcurl4-openssl-dev', 'libjansson-dev', 'libssl-dev', 'libgmp-dev', 'make', 'autotools-dev', 'libtool', 'psmisc', 'bsdmainutils', 'libminiupnpc-dev', 'libevent-dev', 'cmake', 'screen', 'atop', 'ncdu', 'fail2ban', 'ntp']
        state: latest 
        update_cache: yes

###ssh configuration manipulation ###
    - name: sshd config file update
      blockinfile:
        path: /etc/ssh/sshd_config
        insertbefore: BOF # Beginning of the file
        marker: "# {mark} ANSIBLE MANAGED BLOCK BY LINUX-ADMIN"
        block: |
          Port {{ sshd_config_port }}
          UsePAM yes
          PermitRootLogin no
          PubkeyAuthentication yes
          PermitEmptyPasswords no
          PasswordAuthentication no
          ChallengeResponseAuthentication no
        backup: yes
        validate: /usr/sbin/sshd -T -f %s

### tweak limits ###
    - name: change security limits
      shell: |
        cp /etc/security/limits.conf /etc/security/limits.bak
        echo '*         hard    nproc      1550000' | sudo tee -a /etc/security/limits.conf
        echo '*         soft    nproc      1550000' | sudo tee -a /etc/security/limits.conf
        echo '*         hard    nofile      1550000' | sudo tee -a /etc/security/limits.conf
        echo '*         soft    nofile      1550000' | sudo tee -a /etc/security/limits.conf
        echo 'root      hard    nproc      1550000' | sudo tee -a /etc/security/limits.conf
        echo 'root      soft    nproc      1550000' | sudo tee -a /etc/security/limits.conf
        echo 'root      hard    nofile      1550000' | sudo tee -a /etc/security/limits.conf
        echo 'root      soft    nofile      1550000' | sudo tee -a /etc/security/limits.conf 

    - name: change systemd params
      shell: |
        echo 'DefaultLimitNOFILE=1000000' | sudo tee -a /etc/systemd/system.conf
        echo 'DefaultLimitNOFILE=1000000' | sudo tee -a /etc/systemd/user.conf

    - name: change systemd params
      shell: |
        cp /etc/sysctl.conf /etc/sysctl.bak
        echo 'fs.file-max = 1550000' | sudo tee -a /etc/sysctl.conf
        echo 'vm.max_map_count=1550000' | sudo tee -a /etc/sysctl.conf
        echo always > /sys/kernel/mm/transparent_hugepage/enabled
        echo 'vm.nr_hugepages=128' | sudo tee -a /etc/sysctl.conf
        sysctl -p
        bash -c "cat >/etc/sysctl.d/20-solana-udp-buffers.conf <<EOF
        net.core.rmem_default = 134217728
        net.core.rmem_max = 134217728
        net.core.wmem_default = 134217728
        net.core.wmem_max = 134217728
        EOF"
        sysctl -p /etc/sysctl.d/20-solana-udp-buffers.conf

    - name: change fail2ban params
      shell: |
        cp /etc/fail2ban/jail.conf /etc/fail2ban/jail.local
        sed -i 's/bantime  = 10m/bantime = 60m/' /etc/fail2ban/jail.local
        sed -i 's/#mode   = normal/enabled = true \nmode    = normal/' /etc/fail2ban/jail.local

    - name: change auto-upgrades params
      shell: |
        sed -i 's/Unattended-Upgrade "1"/Unattended-Upgrade "0"/' /etc/apt/apt.conf.d/20auto-upgrades
        echo 'SystemMaxUse=300M' | tee -a /etc/systemd/journald.conf
        echo 'SystemMaxFileSize=100M' | tee -a /etc/systemd/journald.conf

    - name: clean apt cache and install updates
      shell: |
        apt-get clean
        purge-old-kernels -qy
        apt update
        apt autoremove -y; apt autoclean -y

    - name: Checking if blacklist-hetzner.conf file exists
      stat:
        path: /etc/modprobe.d/blacklist-hetzner.conf
      register: hetzner_file

    - name: change hetzner blacklist
      shell: |
        sed -i 's/blacklist mei/#blacklist mei/' /etc/modprobe.d/blacklist-hetzner.conf
        sed -i 's/blacklist mei-me/#blacklist mei-me/' /etc/modprobe.d/blacklist-hetzner.conf
      when: hetzner_file.stat.exists

    - name: tweak cpu params
      shell: |
        echo -e 'ENABLE="true"\nGOVERNOR="performance"' > /etc/default/cpufrequtils

### setup iptables ###
    - name: setup iptables rules, block bogon nets etcetera
      shell: |
        iptables -A OUTPUT -p tcp -s 0/0 -d 10.0.0.0/8 -j DROP
        iptables -A OUTPUT -p tcp -s 0/0 -d 100.64.0.0/10 -j DROP
        iptables -A OUTPUT -p tcp -s 0/0 -d 169.254.0.0/16 -j DROP
        iptables -A OUTPUT -p tcp -s 0/0 -d 192.0.0.0/24 -j DROP
        iptables -A OUTPUT -p tcp -s 0/0 -d 192.0.2.0/24 -j DROP
        iptables -A OUTPUT -p tcp -s 0/0 -d 192.88.99.0/24 -j DROP
        iptables -A OUTPUT -p tcp -s 0/0 -d 198.18.0.0/15 -j DROP
        iptables -A OUTPUT -p tcp -s 0/0 -d 198.51.100.0/24 -j DROP
        iptables -A OUTPUT -p tcp -s 0/0 -d 203.0.113.0/24 -j DROP
        iptables -A OUTPUT -p tcp -s 0/0 -d 224.0.0.0/4 -j DROP
        iptables -A OUTPUT -p tcp -s 0/0 -d 240.0.0.0/4 -j DROP
        iptables -A OUTPUT -p udp -s 0/0 -d 10.0.0.0/8 -j DROP
        iptables -A OUTPUT -p udp -s 0/0 -d 100.64.0.0/10 -j DROP
        iptables -A OUTPUT -p udp -s 0/0 -d 169.254.0.0/16 -j DROP
        iptables -A OUTPUT -p udp -s 0/0 -d 192.0.0.0/24 -j DROP
        iptables -A OUTPUT -p udp -s 0/0 -d 192.0.2.0/24 -j DROP
        iptables -A OUTPUT -p udp -s 0/0 -d 192.88.99.0/24 -j DROP
        iptables -A OUTPUT -p udp -s 0/0 -d 198.18.0.0/15 -j DROP
        iptables -A OUTPUT -p udp -s 0/0 -d 198.51.100.0/24 -j DROP
        iptables -A OUTPUT -p udp -s 0/0 -d 203.0.113.0/24 -j DROP
        iptables -A OUTPUT -p udp -s 0/0 -d 224.0.0.0/4 -j DROP
        iptables -A OUTPUT -p udp -s 0/0 -d 240.0.0.0/4 -j DROP
        netfilter-persistent save
        iptables -A OUTPUT -p tcp -s 0/0 -d 192.168.0.0/16 -j DROP
        iptables -A OUTPUT -p udp -s 0/0 -d 192.168.0.0/16 -j DROP


### setup ufw ###
    - name: ufw rule for custom ssh port
      ufw: 
        rule: allow
        port: '{{ sshd_config_port }}'
        proto: tcp
        comment: allow sshd port

    - name: ufw rule for prometheus_node_exporter
      ufw: 
        rule: allow
        src: '{{ prometheus_source_ip }}'
        port: '{{ prometheus_port }}'
        proto: tcp
        comment: allow from prometheus host

    - name: Enable UFW
      ufw:
        state: enabled
        policy: deny
 
### setup time on the server ### 
    - name: configure time sync
      shell: |
        timedatectl set-ntp false
        ntpq -p

### node_exporter ###

    - name: Install node_exporter systemd unit file
      template: 
        src: node_exporter.service.j2 
        dest: "{{ systemd_path }}/node_exporter.service"
        mode: '0600'

    - name: Download node_exporter binary to local folder and unpack
      ansible.builtin.unarchive:
        src: "https://github.com/prometheus/node_exporter/releases/download/v{{ node_exporter_version }}/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}.tar.gz"
        dest: /tmp
        remote_src: yes

    - name: Propagate node_exporter binaries
      copy:
        src: "/tmp/node_exporter-{{ node_exporter_version }}.linux-{{ go_arch }}/node_exporter"
        dest: "{{ _node_exporter_binary_install_dir }}/node_exporter"
        remote_src: yes
        mode: 0755
        owner: root
        group: root

### create sudo group ###  
    - name: Make sure we have a 'sudo' group
      group:
        name: sudo
        state: present

    - name: Change group sudo to passwordless
      lineinfile:
        path: /etc/sudoers
        state: present
        regexp: '^%sudo'
        line: '%sudo ALL=(ALL) NOPASSWD: ALL'
        validate: 'visudo -cf %s'

### systemd manipulations ###
    - name: restart cpufrequtils service
      systemd:
        name: cpufrequtils
        state: restarted

    - name: enable netfilter service
      systemd:
        name: netfilter-persistent
        enabled: yes

    - name: start node_exporter service
      systemd:
        name: node_exporter
        state: started
        enabled: yes

    - name: restart fail2ban service
      systemd:
        name: fail2ban
        state: restarted

    - name: restart sshd service
      systemd:
        name: sshd
        state: restarted
        
#     - name: Creating a file hosts.allow file
#       copy:
#        dest: "/etc/hosts.allow"
#        content: |
#          sshd : localhost : allow
#          sshd : YOUR-IP1 : allow
#          sshd : YOUR-IP1 : allow
#          sshd : ALL : deny