Blue-Green deployment avec Ansible

Principe du Blue-Green

Deux environnements identiques : Blue (actif) et Green (inactif). On deploie sur le Green, puis on bascule le trafic.

Playbook Blue-Green

- hosts: localhost
  vars:
    current_env: "{{ lookup('file', '/opt/deploy/current_env') }}"
    target_env: "{{ 'green' if current_env == 'blue' else 'blue' }}"

  tasks:
    - name: Afficher l'environnement cible
      ansible.builtin.debug:
        msg: "Deploiement sur {{ target_env }} (actif: {{ current_env }})"

- hosts: "{{ target_env }}_servers"
  tasks:
    - name: Deployer la nouvelle version
      include_role:
        name: deploy_app
      vars:
        app_version: "{{ new_version }}"

    - name: Verifier la sante de l'application
      ansible.builtin.uri:
        url: "http://{{ inventory_hostname }}:8080/health"
        status_code: 200
      retries: 20
      delay: 5
      register: health
      until: health.status == 200

- hosts: localhost
  tasks:
    - name: Executer les tests d'integration
      ansible.builtin.command:
        cmd: "python /opt/tests/integration.py --target={{ target_env }}"
      register: integration_tests
      failed_when: integration_tests.rc != 0

    - name: Basculer le load balancer
      ansible.builtin.template:
        src: haproxy.cfg.j2
        dest: /etc/haproxy/haproxy.cfg
      vars:
        active_backend: "{{ target_env }}"
      delegate_to: "{{ lb_host }}"
      notify: reload_haproxy

    - name: Enregistrer le nouvel environnement actif
      ansible.builtin.copy:
        content: "{{ target_env }}"
        dest: /opt/deploy/current_env

    - name: Notifier l'equipe
      community.general.slack:
        token: "{{ slack_token }}"
        channel: "#deployments"
        msg: "Deploiement {{ new_version }} termine. Environnement actif : {{ target_env }}"

Rollback instantane

- hosts: localhost
  vars:
    current_env: "{{ lookup('file', '/opt/deploy/current_env') }}"
    rollback_env: "{{ 'green' if current_env == 'blue' else 'blue' }}"

  tasks:
    - name: Rollback - basculer vers l'ancien environnement
      ansible.builtin.template:
        src: haproxy.cfg.j2
        dest: /etc/haproxy/haproxy.cfg
      vars:
        active_backend: "{{ rollback_env }}"
      delegate_to: "{{ lb_host }}"
      notify: reload_haproxy

    - name: Mettre a jour l'environnement actif
      ansible.builtin.copy:
        content: "{{ rollback_env }}"
        dest: /opt/deploy/current_env

Template HAProxy pour Blue-Green

# templates/haproxy.cfg.j2
frontend http
    bind *:80
    default_backend {{ active_backend }}

backend blue
{% for host in groups['blue_servers'] %}
    server {{ host }} {{ hostvars[host].ansible_host }}:8080 check
{% endfor %}

backend green
{% for host in groups['green_servers'] %}
    server {{ host }} {{ hostvars[host].ansible_host }}:8080 check
{% endfor %}