Use Docker healthchecks for memcached services

This change enables the use of Docker healthchecks for memcached services.
Implements: blueprint container-health-check

Change-Id: I571e6d6cac634fd86429e12b946d6f7b4a2ab02c

ansible/roles/memcached/defaults/main.yml

@@ -9,6 +9,7 @@ memcached_services:
     group: "memcached"
     volumes: "{{ memcached_default_volumes + memcached_extra_volumes }}"
     dimensions: "{{ memcached_dimensions }}"
+    healthcheck: "{{ memcached_healthcheck }}"
     haproxy:
       memcached:
         enabled: "{{ enable_memcached|bool and enable_haproxy_memcached|bool }}"
@@ -36,6 +37,19 @@ memcached_tag: "{{ openstack_tag }}"
 memcached_image_full: "{{ memcached_image }}:{{ memcached_tag }}"
 memcached_dimensions: "{{ default_container_dimensions }}"
 
+memcached_enable_healthchecks: "{{ enable_container_healthchecks }}"
+memcached_healthcheck_interval: "{{ default_container_healthcheck_interval }}"
+memcached_healthcheck_retries: "{{ default_container_healthcheck_retries }}"
+memcached_healthcheck_start_period: "{{ default_container_healthcheck_start_period }}"
+memcached_healthcheck_test: ["CMD-SHELL", "healthcheck_listen memcached {{ memcached_port }}"]
+memcached_healthcheck_timeout: "{{ default_container_healthcheck_timeout }}"
+memcached_healthcheck:
+  interval: "{{ memcached_healthcheck_interval }}"
+  retries: "{{ memcached_healthcheck_retries }}"
+  start_period: "{{ memcached_healthcheck_start_period }}"
+  test: "{% if memcached_enable_healthchecks | bool %}{{ memcached_healthcheck_test }}{% else %}NONE{% endif %}"
+  timeout: "{{ memcached_healthcheck_timeout }}"
+
 memcached_default_volumes:
   - "{{ node_config_directory }}/memcached/:{{ container_config_directory }}/:ro"
   - "/etc/localtime:/etc/localtime:ro"

ansible/roles/memcached/handlers/main.yml

@@ -10,5 +10,6 @@
     name: "{{ service.container_name }}"
     volumes: "{{ service.volumes }}"
     dimensions: "{{ service.dimensions }}"
+    healthcheck: "{{ service.healthcheck | default(omit) }}"
   when:
     - kolla_action != "config"

ansible/roles/memcached/tasks/check-containers.yml

@@ -10,6 +10,7 @@
     image: "{{ service.image }}"
     volumes: "{{ service.volumes }}"
     dimensions: "{{ service.dimensions }}"
+    healthcheck: "{{ service.healthcheck | default(omit) }}"
   when:
     - inventory_hostname in groups[service.group]
     - service.enabled | bool

releasenotes/notes/implement-docker-healthchecks-for-memcached-807b9036c3c92596.yaml

+---
+features:
+  - |
+    Implements container healthchecks for memcached services.
+    See `blueprint
+    <https://blueprints.launchpad.net/kolla-ansible/+spec/container-health-check>`__