Add external LB management handler hook interface

Based on conversation on an ansible issue[1], I implemented
a LB orchestration role[2] similar to the POC here[3].

This will allow external loadbalancer management roles to hook
into a universal notify listener "Manage LB" to perform before/
after endpoint management actions when the service is being
restarted.

[1]: https://github.com/ansible/ansible/issues/27813
[2]: https://github.com/Logan2211/ansible-haproxy-endpoints
[3]: https://github.com/Logan2211/tmp-ansible-27813

Change-Id: Ide9efbc79e4fd2c761a3ee4f463f501181da1df2

doc/source/index.rst

@@ -53,6 +53,19 @@ Example playbook
 .. literalinclude:: ../../examples/playbook.yml
    :language: yaml
 
+External Restart Hooks
+~~~~~~~~~~~~~~~~~~~~~~
+
+When the role performs a restart of the service, it will notify an Ansible
+handler named ``Manage LB``, which is a noop within this role. In the
+playbook, other roles may be loaded before and after this role which will
+implement Ansible handler listeners for ``Manage LB``, allowing external roles
+to manage the load balancer endpoints responsible for sending traffic to the
+servers being restarted by marking them in maintenance or active mode,
+draining sessions, etc. For an example implementation, please reference the
+`ansible-haproxy-endpoints role <https://github.com/Logan2211/ansible-haproxy-endpoints>`_
+used by the openstack-ansible project.
+
 Tags
 ~~~~
 

handlers/main.yml

@@ -103,3 +103,7 @@
   until: _restart | success
   retries: 5
   delay: 2
+
+- meta: noop
+  listen: Manage LB
+  when: false

tasks/keystone_apache.yml

@@ -42,6 +42,7 @@
   when:
     - ansible_pkg_mgr in ['apt', 'zypper']
   notify:
+    - Manage LB
     - Restart web server
 
 ## NOTE(andymccr):
@@ -54,6 +55,7 @@
   when:
    - ansible_pkg_mgr in ['yum', 'dnf']
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Drop apache2 config files
@@ -64,6 +66,7 @@
     group: "root"
   with_items: "{{ keystone_apache_configs }}"
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Disable default apache site
@@ -72,6 +75,7 @@
     state: "absent"
   with_items: "{{ keystone_apache_default_sites }}"
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Enabled keystone vhost
@@ -83,6 +87,7 @@
     - keystone_apache_site_available is defined
     - keystone_apache_site_enabled is defined
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Ensure Apache ServerName
@@ -90,6 +95,7 @@
     dest: "{{ keystone_apache_conf }}"
     line: "ServerName {{ ansible_hostname }}"
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Ensure Apache ServerTokens
@@ -98,6 +104,7 @@
     regexp: '^ServerTokens'
     line: "ServerTokens {{ keystone_apache_servertokens }}"
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Ensure Apache ServerSignature
@@ -106,6 +113,7 @@
     regexp: '^ServerSignature'
     line: "ServerSignature {{ keystone_apache_serversignature }}"
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Remove Listen from Apache config
@@ -115,4 +123,5 @@
     backrefs: yes
     line: '#\1'
   notify:
+    - Manage LB
     - Restart web server

tasks/keystone_db_setup.yml

@@ -64,6 +64,7 @@
     - "'systemd could not find' not in _stop.msg"
     - "'Could not find the requested service' not in _stop.msg"
   notify:
+    - Manage LB
     - Restart uWSGI
 
 - name: Perform a Keystone DB sync expand

tasks/keystone_federation_sp_setup.yml

@@ -33,6 +33,7 @@
   changed_when: false
   when: inventory_hostname == groups['keystone_all'][0]
   notify:
+    - Manage LB
     - Restart web server
     - Restart Shibd
 
@@ -65,6 +66,7 @@
     mode: "0640"
   when: inventory_hostname != groups['keystone_all'][0]
   notify:
+    - Manage LB
     - Restart web server
     - Restart Shibd
 
@@ -77,6 +79,7 @@
     mode: "0640"
   when: inventory_hostname != groups['keystone_all'][0]
   notify:
+    - Manage LB
     - Restart web server
     - Restart Shibd
 
@@ -90,5 +93,6 @@
     - "/etc/shibboleth/sp-key.pem"
   when: inventory_hostname != groups['keystone_all'][0]
   notify:
+    - Manage LB
     - Restart web server
     - Restart Shibd

tasks/keystone_idp_metadata.yml

@@ -20,4 +20,5 @@
   become_user: "{{ keystone_system_user_name }}"
   when: keystone_idp != {}
   notify:
+    - Manage LB
     - Restart uWSGI

tasks/keystone_idp_self_signed_create.yml

@@ -33,6 +33,7 @@
   when: >
     inventory_hostname == groups['keystone_all'][0]
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Set appropriate file ownership on the IdP self-signed cert

tasks/keystone_idp_self_signed_distribute.yml

@@ -30,6 +30,7 @@
   retries: 5
   delay: 2
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Set appropriate file ownership on the IdP self-signed cert

tasks/keystone_init_systemd.yml

@@ -39,6 +39,7 @@
     owner: "root"
     group: "root"
   notify:
+    - Manage LB
     - Restart uWSGI
     - Restart web server
 
@@ -53,5 +54,6 @@
     config_type: "ini"
   with_items: "{{ keystone_wsgi_program_names }}"
   notify:
+    - Manage LB
     - Restart uWSGI
     - Restart web server

tasks/keystone_install.yml

@@ -78,6 +78,7 @@
   retries: 5
   delay: 2
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Create developer mode constraint file
@@ -137,6 +138,7 @@
     copy: "no"
   when: keystone_get_venv | changed
   notify:
+    - Manage LB
     - Restart uWSGI
     - Restart web server
 
@@ -156,6 +158,7 @@
   delay: 2
   when: keystone_get_venv | failed or keystone_get_venv | skipped
   notify:
+    - Manage LB
     - Restart uWSGI
     - Restart web server
 
@@ -184,6 +187,7 @@
     - src: "{{ keystone_bin }}/keystone-wsgi-public"
       dest: main
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Initialise the upgrade facts

tasks/keystone_ldap_setup.yml

@@ -35,6 +35,7 @@
     mode: "0640"
   with_dict: "{{ keystone_ldap }}"
   notify:
+    - Manage LB
     - Restart uWSGI
     - Restart web server
 
@@ -47,5 +48,6 @@
     state: absent
   when: keystone_ldap.Default is not defined
   notify:
+    - Manage LB
     - Restart uWSGI
     - Restart web server

tasks/keystone_nginx.yml

@@ -24,6 +24,7 @@
     path: /etc/nginx/sites-enabled/default
     state: absent
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Configure custom nginx log format
@@ -34,6 +35,7 @@
     dest: "/etc/nginx/nginx.conf"
     line: "log_format custom '{{ keystone_nginx_access_log_format_combined }} {{ keystone_nginx_access_log_format_extras }}';"
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Ensure configuration directory exists
@@ -48,6 +50,7 @@
     dest: "/etc/nginx/{{ keystone_nginx_conf_path }}/{{ item }}.conf"
   with_items: "{{ keystone_wsgi_program_names }}"
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Link to enable virtual hosts
@@ -58,4 +61,5 @@
   with_items: "{{ keystone_wsgi_program_names }}"
   when: ansible_os_family == "Debian"
   notify:
+    - Manage LB
     - Restart web server

tasks/keystone_post_install.yml

@@ -54,6 +54,7 @@
       config_type: "json"
       content: "{{ keystone_policy_user_content | default('{}', true) }}"
   notify:
+    - Manage LB
     - Restart uWSGI
     - Restart web server
 
@@ -67,6 +68,7 @@
   when:
     - keystone_idp != {}
   notify:
+    - Manage LB
     - Restart uWSGI
     - Restart web server
 
@@ -77,5 +79,6 @@
   when:
     - keystone_idp == {}
   notify:
+    - Manage LB
     - Restart uWSGI
     - Restart web server

tasks/keystone_ssl_key_create.yml

@@ -29,6 +29,7 @@
     -extensions v3_ca
     creates={{ keystone_ssl_cert }}
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Ensure keystone user owns the self-signed key and certificate
@@ -41,4 +42,5 @@
     - "{{ keystone_ssl_key }}"
     - "{{ keystone_ssl_cert }}"
   notify:
+    - Manage LB
     - Restart web server

tasks/keystone_ssl_key_distribute.yml

@@ -21,6 +21,7 @@
     group: "{{ keystone_system_group_name }}"
     mode: "0640"
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Distribute self signed ssl cert
@@ -31,6 +32,7 @@
     group: "{{ keystone_system_group_name }}"
     mode: "0640"
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Ensure keystone user owns the self-signed key and certificate
@@ -42,4 +44,5 @@
     - "{{ keystone_ssl_key }}"
     - "{{ keystone_ssl_cert }}"
   notify:
+    - Manage LB
     - Restart web server

tasks/keystone_ssl_user_provided.yml

@@ -22,6 +22,7 @@
     mode: "0644"
   when: keystone_user_ssl_cert is defined
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Drop user provided ssl key
@@ -33,6 +34,7 @@
     mode: "0640"
   when: keystone_user_ssl_key is defined
   notify:
+    - Manage LB
     - Restart web server
 
 - name: Drop user provided ssl CA cert
@@ -44,4 +46,5 @@
     mode: "0644"
   when: keystone_user_ssl_ca_cert is defined
   notify:
+    - Manage LB
     - Restart web server

tasks/keystone_uwsgi.yml

@@ -27,6 +27,7 @@
     config_type: ini
   with_items: "{{ keystone_wsgi_program_names }}"
   notify:
+    - Manage LB
     - Restart uWSGI
 
 - include: "keystone_init_{{ ansible_service_mgr }}.yml"