ansible-role-apache/lamp_haproxy/rolling_update.yml

---
# This playbook does a rolling update for all webservers serially (one at a time).
# Change the value of serial: to adjust the number of server to be updated.
#
# The three roles that apply to the webserver hosts will be applied: common,
# base-apache, and web. So any changes to configuration, package updates, etc,
# will be applied as part of the rolling update process.
# 

# gather facts from monitoring nodes for iptables rules
- hosts: monitoring
  tasks: []

- hosts: webservers
  user: root
  serial: 1
  
  # These are the tasks to run before applying updates:
  pre_tasks:
  - name: disable nagios alerts for this host webserver service
    nagios: action=disable_alerts host={{ ansible_hostname }} services=webserver
    delegate_to: "{{ item }}"
    with_items: groups.monitoring

  - name: disable the server in haproxy
    shell: echo "disable server myapplb/{{ ansible_hostname }}" | socat stdio /var/lib/haproxy/stats
    delegate_to: "{{ item }}"
    with_items: groups.lbservers

  roles:
  - common
  - base-apache
  - web

  # These tasks run after the roles:
  post_tasks:
  - name: Enable the server in haproxy
    shell: echo "enable server myapplb/{{ ansible_hostname }}" | socat stdio /var/lib/haproxy/stats
    delegate_to: "{{ item }}"
    with_items: groups.lbservers

  - name: re-enable nagios alerts
    nagios: action=enable_alerts host={{ ansible_hostname }} services=webserver
    delegate_to: "{{ item }}"
    with_items: groups.monitoring