pivot.yml

---
# run like this: ANSIBLE_HOST_KEY_CHECKING=False ansible-playbook -i 1.2.3.4, test.yml

- name: Pivot root to ramdisk
  hosts: all
  vars:
    ansible_user: root
  gather_facts: false
  tasks:
    - name: Create directories
      file:
        path: /ramdisk
        state: directory

    - name: Mount
      command: mount -t tmpfs -o size=100% none /ramdisk

    - name: Create directories
      file:
        path: "/ramdisk/{{ item }}"
        state: directory
      loop:
        - proc
        - sys
        - dev
        - oldroot

    - name: Run script
      shell: |
        set -e
        cp -ax / /ramdisk
        mount --make-rprivate /
        set +e
        for i in dev proc sys run; do mount --move /$i /ramdisk/$i; done
        set -e
        pivot_root /ramdisk /ramdisk/oldroot
        swapoff -a

    - name: Install psmisc
      package:
        name: psmisc

    - name: Restart daemons
      systemd:
        name: "{{ item }}"
        state: restarted
        daemon_reexec: true
      loop:
        - cron
        - dbus
        - rsyslog
        - sshd
        - systemd-journald
        - systemd-logind
        - systemd-timesyncd
        - systemd-udevd

    - name: Kill oldroot
      shell: "sleep 2 && fuser -km /oldroot"
      async: 1
      poll: 0

    - name: Sleep
      pause:
        seconds: 5

    - name: Reset connection
      meta: reset_connection

    - name: Unmount oldroot
      mount:
        path: /oldroot
        state: unmounted
        fstab: /tmp/fstab

    - name: Make / shared
      command: mount --make-rshared /