Enable RabbitMQ mirrored queues

docs/using_lagoon/docker_images/rabbitmq.md

@@ -0,0 +1,34 @@
+# rabbitmq Image
+amazee.io RabbitMQ Dockerfile with management plugin installed, based on the official rabbitmq:3-management image at [docker-hub](https://hub.docker.com/_/rabbitmq).
+
+This Dockerfile is intended to be used to setup a standalone RabbitMQ queue broker as well as base image to setup a cluster with HA queues support by default ([Mirrored queues](https://www.rabbitmq.com/ha.html)).   
+By default the RabbitMQ broker is started as single node. If you want to start a cluster, you need to use the [`rabbitmq-cluster`](https://github.com/amazeeio/lagoon/blob/master/images/rabbitmq-cluster/Dockerfile) Docker image, based on `rabbitmq` image plus the `rabbitmq_peer_discovery_k8s` plugin.
+
+## amazee.io & OpenShift adaptions
+This image is prepared to be used on amazee.io which leverages OpenShift. There are therefore some things already done:
+
+- Folder permissions are automatically adapted with [`fix-permissions`](https://github.com/sclorg/s2i-base-container/blob/master/core/root/usr/bin/fix-permissions) so this image will work with a random user and therefore also on OpenShift.
+- The file `/etc/rabbitmq/definitions.json` is parsed through [envplate](https://github.com/kreuzwerker/envplate) with an container-entrypoint.
+
+## Included RabbitMQ default schema (definitions.json)
+To enable the support for Mirrored Queues, at least one [`policy`](https://www.rabbitmq.com/parameters.html#policies) must exists.   
+Into the `definitions.json` schema file, are definied the minimal entities to let the container running: virtualhost (vhost), username and password to access management UI, permissions and policies.  
+
+By default a policy called `lagoon-ha` is created at startup but it is not active because it doesn't match any queue's name pattern (see default [Environment Variables](#environment-variables)).  
+```
+"policies":[
+        {"vhost":"${RABBITMQ_DEFAULT_VHOST}","name":"lagoon-ha","pattern":"${RABBITMQ_DEFAULT_HA_PATTERN}", "definition":{"ha-mode":"exactly","ha-params":2,"ha-sync-mode":"automatic","ha-sync-batch-size":5}}
+  ]
+```
+By default, the `ha-mode` is set to `exactly` which controls the exact number of mirroring nodes for a queue (mirrors). The number of nodes, is controller by `ha-params`.   
+For furhter and custom configuration, please refer to [official RabbitMQ documentation](https://www.rabbitmq.com/ha.html).
+
+## Environment Variables
+Environment variables defined in RabbitMQ base image
+
+| Environment Variable              | Default   | Description                                    |
+| --------------------------------- | --------- | ---------------------------------------------- |
+| `RABBITMQ_DEFAULT_USER`           |   guest 	| Username for management UI access              |
+| `RABBITMQ_DEFAULT_PASS`           |   guest 	| Password for management UI access              |
+| `RABBITMQ_DEFAULT_VHOST`          |   /	| RabbitMQ main virtualhost|
+| `RABBITMQ_DEFAULT_HA_PATTERN`     |   ^$	| Regular expression to match for mirrored queues|

mkdocs.yml

@@ -17,6 +17,7 @@ pages:
   - Docker Images:
     - PHP-FPM: using_lagoon/docker_images/php-fpm.md
     - Nginx: using_lagoon/docker_images/nginx.md
+    - RabbitMQ: using_lagoon/docker_images/rabbitmq.md
   - Workflows: using_lagoon/workflows.md
   - Backups: using_lagoon/backups.md
   - Logging: using_lagoon/logging.md