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offline/federation_preparation.md

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+## RabbitMQ
+
+There are two methods to deploy the RabbitMQ cluster:
+
+### Method 1: Install RabbitMQ inside kubernetes cluster with the help of helm chart
+
+To install the RabbitMQ service, first copy the value and secret files:
+```
+cp ./values/rabbitmq/prod-values.example.yaml ./values/rabbitmq/values.yaml
+cp ./values/rabbitmq/prod-secrets.example.yaml ./values/rabbitmq/secrets.yaml
+```
+By default this will create a RabbitMQ deployment with ephemeral storage. To use the local persistence storage of Kubernetes nodes, please refer to the related documentation in [offline/local_persistent_storage_k8s.md](./local_persistent_storage_k8s.md).
+
+Now, update the `./values/rabbitmq/values.yaml` and `./values/rabbitmq/secrets.yaml` with correct values as needed.
+
+Deploy the `rabbitmq` helm chart:
+```
+d helm upgrade --install rabbitmq ./charts/rabbitmq --values ./values/rabbitmq/values.yaml --values ./values/rabbitmq/secrets.yaml
+```
+
+### Method 2: Install RabbitMQ outside of the Kubernetes cluster with an Ansible playbook
+
+Add the nodes on which you want to run rabbitmq to the `[rmq-cluster]` group in the `ansible/inventory/offline/hosts.ini` file. Also, update the `ansible/roles/rabbitmq-cluster/defaults/main.yml` file with the correct configurations for your environment.
+
+If you need RabbitMQ to listen on a different interface than the default gateway, set `rabbitmq_network_interface`
+
+You should have following entries in the `/ansible/inventory/offline/hosts.ini` file. For example:
+```
+[rmq-cluster:vars]
+rabbitmq_network_interface = enp1s0
+
+[rmq-cluster]
+ansnode1
+ansnode2
+ansnode3
+```
+
+**Important:** RabbitMQ nodes address each other using a node name, for e.g rabbitmq@ansnode1
+Please refer to the official documentation and configure your DNS based on the setup - https://www.rabbitmq.com/clustering.html#cluster-formation-requirements
+
+
+For adding entries to local host file(`/etc/hosts`), run
+```
+d ansible-playbook -i ansible/inventory/offline/hosts.ini ansible/roles/rabbitmq-cluster/tasks/configure_dns.yml
+```
+
+Create the rabbitmq cluster:
+
+``` 
+d ansible-playbook -i ansible/inventory/offline/hosts.ini ansible/rabbitmq.yml
+```
+
+Uncomment the following section, in the `ansible/helm_external.yml` file:
+```
+# - hosts: "rmq-cluster"
+#   become: false
+#   tasks:
+#     - name: Generate rabbitmq IPs for helm
+#       include_tasks: tasks/helm_external.yml
+#       vars:
+#         external_dir_name: rabbitmq-external
+#         server_type: rmq-cluster
+#         network_interface: "{{ rabbitmq_network_interface }}"
+
+```
+
+and run the following playbook to create values file for helm charts to look for RabbitMQ IP addresses -
+
+```
+d ansible-playbook -i ./ansible/inventory/offline/hosts.ini ansible/helm_external.yml
+```
+
+Make Kubernetes aware of where RabbitMQ external stateful service is running:
+```
+d helm install rabbitmq-external ./charts/rabbitmq-external --values ./values/rabbitmq-external/values.yaml
+```
+
+Configure wire-server to use the external RabbitMQ service:
+
+Edit the `/values/wire-server/prod-values.yaml` file to update the RabbitMQ host
+Under `brig` and `galley` section, you will find the `rabbitmq` config, update the host to `rabbitmq-external`, it should look like this:
+```
+rabbitmq:
+  host: rabbitmq-external
+```