---
- hosts: "{{ hostlist }}"
  become: true
  become_user: root
  handlers:
    - name: restart ssh
      service: name=ssh state=restarted
  vars:
    copy_local_key: "{{ lookup('file', lookup('env','HOME') + '/.ssh/id_rsa.pub') }}"
  tasks:
    # update deps
    - name: update apt
      apt:
        update_cache: true

    # upgrade deps
    - name: upgrade deps
      apt:
        upgrade: safe
        update_cache: true

    # install deps
    - name: install deps
      apt:
        name:
          - build-essential
          - curl
          - git
          - vim
          - libtool
          - automake
          - autoconf
          - nasm
        update_cache: true

    # create devops group
    - name: create devops group
      group:
        name: devops
        state: present

    - name: set devops group to have sudo access
      lineinfile:
        path: /etc/sudoers
        state: present
        regexp: ^%devops
        line: '%devops ALL=(ALL) NOPASSWD: ALL'
        validate: /usr/sbin/visudo -cf %s

    # create devops user (with sudo)
    - name: create a devops user with sudo privileges
      user:
        name: devops
        state: present
        groups: devops,www-data
        append: true
        create_home: true
        shell: /bin/bash

    - name: set authorized key for devops user
      authorized_key:
        user: devops
        state: present
        key: '{{ copy_local_key }}'

    # create deploy user
    - name: create a deploy user
      user:
        name: deploy
        state: present
        groups: www-data
        append: true
        create_home: true
        shell: /bin/bash
        generate_ssh_key: true
        ssh_key_bits: 4096

    - name: set authorized key for deploy user
      authorized_key:
        user: deploy
        state: present
        key: '{{ copy_local_key }}'

    # TODO: change root password to randomly generated value

    # configure ssh
    - name: disable root login
      lineinfile:
        path: /etc/ssh/sshd_config
        state: present
        regexp: '^#?PermitRootLogin'
        line: PermitRootLogin no
      notify: restart ssh

    - name: disable password authentication
      lineinfile:
        path: /etc/ssh/sshd_config
        state: present
        regexp: '^PasswordAuthentication'
        line: 'PasswordAuthentication no'
      notify: restart ssh

    # TODO: we can probably remove the `./templates/security-limits.d-mongod.conf`
    # modify ulimit for devops and deploy
    # https://gist.github.com/visualskyrim/8d93a8be0a3ef6dd6598ec8550f6eadd#file-modify_ulimit-yml-L7
    - name: configure system settings, file descriptors and number of threads
      pam_limits:
        domain: '*'
        limit_type: "{{item.limit_type}}"
        limit_item: "{{item.limit_item}}"
        value: "{{item.value}}"
      with_items:
        - {limit_type: '-', limit_item: 'nofile', value: 65536}
        - {limit_type: '-', limit_item: 'nproc', value: 65536}
        - {limit_type: 'soft', limit_item: 'memlock', value: unlimited}
        - {limit_type: 'hard', limit_item: 'memlock', value: unlimited}
    - name: reload settings from all system configuration files
      shell: sysctl --system

- hosts: "{{ hostlist }}"
  become: true
  become_user: root
  vars:
    #
    # kernel tuning and performance optimizations
    #
    # https://medium.com/@k1d_bl4ck/a-quick-story-about-node-js-socket-io-and-the-linux-tcp-stack-bf1e8318b20e
    # https://gist.github.com/vongosling/9929680
    # https://wiki.mikejung.biz/Sysctl_tweaks
    # https://docs.continuent.com/tungsten-clustering-6.1/performance-networking.html
    # https://www.vpndada.com/how-to-setup-a-shadowsocks-server-on-digitalocean/
    #
    # TODO: we should research more configuration settings from these links:
    #       https://udgwebdev.github.io/tunning-em-servidor-linux/
    #       https://gist.github.com/voluntas/bc54c60aaa7ad6856e6f6a928b79ab6c
    #       https://serverdiary.com/linux/how-to-mitigate-tcp-syn-flood-attack-and-resolve-it-on-linux/
    #
    sysctl_settings:
      #
      # handle ufw forwarding
      #
      - name: net.ipv4.ip_forward
        value: 1
      - name: net.ipv6.conf.default.forwarding
        value: 1
      - name: net.ipv6.conf.all.forwarding
        value: 1

      # sets the time before the kernel considers
      # migrating a process to another core
      - name: kernel.sched_migration_cost_ns
        value: 5000000

      # handle swapping idle processes to disk
      # https://medium.com/@sauravomar01/linux-kernel-tuning-and-performance-tweaks-d7848178aaa2
      - name: vm.swappiness
        value: 10
      - name: vm.dirty_ratio
        value: 60
      - name: vm.dirty_background_ratio
        value: 2
      - name: vm.vfs_cache_pressure
        value: 50

      # allow local port range
      - name: net.ipv4.ip_local_port_range
        value: 1024 65535

      # increase amount of option memory buffers
      - name: net.core.optmem_max
        value: 25165824

      # max number of concurrently open files
      - name: fs.file-max
        value: 2097152

      # increase the max number of "backlogged sockets" (default: 128)
      # (max number of connections that can be queued for acceptance)
      - name: net.core.somaxconn
        value: 1024

      # length of time orphaned (unreferenced) connection will wait (default: 60)
      - name: net.ipv4.tcp_fin_timeout
        value: 30

      #
      # allow more aggressive network throughput
      # https://en.wikipedia.org/wiki/TCP_window_scale_option
      #
      - name: net.ipv4.tcp_window_scaling
        value: 1

      #
      # configure tcp keepalive
      # https://webhostinggeeks.com/howto/configure-linux-tcp-keepalive-setting/
      #
      - name: net.ipv4.tcp_keepalive_time
        value: 60
      - name: net.ipv4.tcp_keepalive_intvl
        value: 10
      #
      # NOTE: it seems like this was removed in newer kernels
      # `sysctl: cannot stat /proc/sys/net/ipv4/tcp_tw_recycle: No such file or directory`
      #
      # - name: net.ipv4.tcp_keepalive_probe
      # - value: 6

      # max remembered connection requests which did not yet receive ACK (default: 1024)
      # (how many half-open connections can be kept in the queue)
      - name: net.ipv4.tcp_max_syn_backlog
        value: 4096

      # increase system ip port limts to allow for more connections
      - name: net.ipv4.ip_local_port_range
        value: 1024 65535

      # number of packets queued on INPUT (default: 1000)
      - name: net.core.netdev_max_backlog
        value: 4096

      #
      # enable BBR congestion control and make HTTP/2 work reliably
      # https://blog.cloudflare.com/http-2-prioritization-with-nginx/#comment-4147796381
      #
      - name: net.core.default_qdisc
        value: fq
      - name: net.ipv4.tcp_congestion_control
        value: bbr
      - name: net.ipv4.tcp_notsent_lowat
        value: 16384

      # protect against tcp time-wait
      - name: net.ipv4.tcp_rfc1337
        value: 1

      #
      # number of sockets in the "time-wait" state allowed to exist (prevents simple DOS attacks)
      # https://easyengine.io/tutorials/linux/sysctl-conf/
      # https://docs.continuent.com/tungsten-clustering-5.4/performance-networking.html
      #
      - name: net.ipv4.tcp_max_tw_buckets
        value: 1440000

      #
      # we do not use this because it does not work well with load balancers
      # and it also was removed from linux in v4.12
      # https://stackoverflow.com/questions/6426253/tcp-tw-reuse-vs-tcp-tw-recycle-which-to-use-or-both
      #
      # NOTE: this was removed/deprecated in newer kernels
      # `sysctl: cannot stat /proc/sys/net/ipv4/tcp_tw_recycle: No such file or directory`
      #
      # - name: net.ipv4.tcp_tw_recycle
      #   value: 0

      # allow to reuse TIME_WAIT sockets for new connections when safe from protocol
      - name: net.ipv4.tcp_tw_reuse
        value: 1

      # increasing tcp receiving buffer memory size will help large file uploads
      - name: net.ipv4.tcp_rmem
        value: 4096 12582912 16777216

      # increase tcp receiving memory to 16MB per socket
      - name: net.core.rmem_max
        value: 16777216

      # increasing tcp send buffers will increase performance (if and only if) sending large files
      - name: net.ipv4.tcp_wmem
        value: 4096 12582912 16777216

      # increase tcp receiving memory to 16MB per socket
      - name: net.core.wmem_max
        value: 16777216

      # provide RFC 2861 behavior and time out congestion window after an idle period
      # many suggest to disable it to improve performance in some cases
      - name: net.ipv4.tcp_slow_start_after_idle
        value: 0

      # disable caching of TCP congestion state
      - name: net.ipv4.tcp_no_metrics_save
        value: 1

      # set number of retries for for TCP 3 way handshake (default is 5)
      # https://www.justsomestuff.co.uk/wiki/doku.php/linux/syn_tcp_timeout
      - name: net.ipv4.tcp_syn_retries
        value: 3

      #
      # number of times SYNACKS for passive TCP connection are tried
      # https://blog.cloudflare.com/syn-packet-handling-in-the-wild/
      #
      - name: net.ipv4.tcp_synack_retries
        value: 2

      #
      # TODO: node.js does not yet support tcp fastopen
      #
      # https://www.keycdn.com/support/tcp-fast-open
      # https://github.com/nodejs/node/issues/8066
      #
      # - name: net.ipv4.tcp_fastopen
      #   value: 3

      #
      # tune ICMP black holes and adjust path MTU in a smart way
      # https://blog.cloudflare.com/path-mtu-discovery-in-practice/
      #
      - name: net.ipv4.tcp_mtu_probing
        value: 1
      - name: net.ipv4.tcp_base_mss
        value: 1024

      #
      # make the system resistant to out of memory scenarios
      # https://www.linbit.com/kernel-min_free_kbytes/
      #
      # (e.g. 8GB ram = 128MB = 131072)
      # (e.g. 4GB ram = 64MB = 65536)
      #
      - name: vm.min_free_kbytes
        value: 65536

      # control syncookies
      - name: net.ipv4.tcp_syncookies
        value: 1

      # enable timestamps as defined in RFC1323
      - name: net.ipv4.tcp_timestamps
        value: 1

      # tells the kernal how many TCP sockets not attached to any user file handle
      # to maintain. if the number is exceeded, orphaned connections are reset and warning printed
      - name: net.ipv4.tcp_max_orphans
        value: 262144

  roles:
    # https://github.com/Oefenweb/ansible-sysctl
    - role: sysctl

    # https://github.com/Oefenweb/ansible-swapfile
    - role: swapfile
      swapfile_size: 4GB
      swapfile_swappiness: '10'
      swapfile_vfs_cache_pressure: '50'

    # https://github.com/Oefenweb/ansible-dns
    - role: dns
      dns_nameservers:
        # cloudflare
        - '1.1.1.1'
        - '1.0.0.1'

    # https://github.com/Oefenweb/ansible-ntp
    - role: ntp
      ntp_servers:
        - 'time.cloudflare.com'

    # https://github.com/Oefenweb/ansible-timezone
    - role: timezone
      timezone_zone: 'America/Chicago'

    # https://github.com/Oefenweb/ansible-fail2ban
    - role: fail2ban

    # https://github.com/jnv/ansible-role-unattended-upgrades
    - role: unattended-upgrades

    # https://github.com/fubarhouse/ansible-role-rust
    # https://github.com/fubarhouse/ansible-role-rust/issues/20
    # - role: rust

    # TODO: set up logrotate for all roles/deps
    #       https://github.com/Oefenweb/ansible-logrotated
- hosts: http:bree
  become: true
  become_user: root
  roles:
    - mongo-shell