RabbitMQ Cluster on kubernetes - Part 1

 RabbitMQ Cluster on Kubernates

RabbitMQ is one of the most widely used open-source message brokers. It was originally based on the Advanced Message Queuing Protocol (AMQP).In the RabbitMQ architecture main components are Producer ,Exchange ,Queue and Consumer application.

In this tutorial, we will use Red Hat® OpenShift® version 4.6. OpenShift is an enterprise-ready Kubernetes container platform with full-stack automated operations to manage hybrid cloud and multi-cloud deployments. Same RabbitMQ cluster deployment we can use any kubernetes container platform.

We will basically deploy a RabbitMQ cluster, a producer application (.Net core application) which will produce messages to a specific queue on RabbitMQ cluster, a consumer application (.Net core application) which will consume messages from the queue. All the application deployed to the worker node, following diagram shows the overview of the rabbitmq cluster on the Openshift. 

Deploy RabbitMQ Cluster

In here I will put every command that can run on both Kubernetes and openshift.

1. let’s create a namespace or project either kubernetes or Openshift.

All resources in Kubernetes are started in a namespace. Unless one is specified. To have better control over the deployment process use the following command to create a distinct namespace. 

               kubectl create ns rabbits

                  oc create project rabbits

   2. Download the yaml files to create the RabbitMQ cluster. Update namespace according to your project.

https://github.com/darshanadinushal/rabbitmq-cluster/blob/master/deployment/rabbitmq-cluster/rabbit-configmap.yaml
https://github.com/darshanadinushal/rabbitmq-cluster/blob/master/deployment/rabbitmq-cluster/rabbit-rbac.yaml
https://github.com/darshanadinushal/rabbitmq-cluster/blob/master/deployment/rabbitmq-cluster/rabbit-secret.yaml

https://github.com/darshanadinushal/rabbitmq-cluster/blob/master/deployment/rabbitmq-cluster/rabbit-statefulset.yaml

      3. Get the Storage Class name and update the  rabbit-statefulset.yaml ,there is a volumeClaimTemplates > storageClassName.

RabbitMQ requires using a Stateful Set to deploy a RabbitMQ cluster to Kubernetes. The Stateful Set ensures that the RabbitMQ nodes are deployed in order, one at a time. There are other, equally important reasons for using a Stateful Set instead of a Deployment: sticky identity, simple network identifiers, stable persistent storage and the ability to perform ordered rolling upgrades.

By using a StatefulSet as is intended for the case where Pods have persistent data that is associated with their "identity. If the RabbitMQ cluster down ,pods restart or pods failure Kubernetes will create new pods ,but having persistent storage rabbitmq queue messages will not delete.

              kubectl get storageclass

                  oc get storageclass   

        Replace here

      4. Deploy the cluster using yaml file.

              Kubernetes:

                  kubectl create -n rabbits -f .\rabbit-rbac.yaml
                       kubectl create -n rabbits -f .\rabbit-configmap.yaml
                       kubectl create -n rabbits -f .\rabbit-secret.yaml
                       kubectl create -n rabbits -f .\rabbit-statefulset.yaml

                  Openshift:

oc create -n rabbits -f .\rabbit-rbac.yaml

oc create -n rabbits -f .\rabbit-configmap.yaml

oc create -n rabbits -f .\rabbit-secret.yaml 

oc create -n rabbits -f .\rabbit-statefulset.yaml

                    

      5. Create route for the service to expose the rabbitMQ cluster to the Internet.

          Openshift:

      Kubernetes: 

                Download the yaml file and execute the following command to create route.

                  https://github.com/darshanadinushal/rabbitmq-cluster/blob/master/deployment/route-kubernetes.yaml

                  kubectl create -n rabbits -f .\route-kubernetes.yaml

      6. Login to the RabbitMQ Cluster.

           Login to the RabbitMQ cluster using user name and password. 

            Username : guest 
            Password : guest

      7. Create new admin user in RabbitMQ. 

To create a new user, we need to login into RabbitMQ web management plugin using  default credentials (guest) like previous steps. 

After logging into the application, create a new user we need to navigate to Admin tab for that click on Admin tab like as shown below.

 After navigate to Admin tab, we can see the default user (“guest”) details who is having “administrator” privileges and below that we have Add a user panel to add new user.

After we click on “Add a user” panel, it will show the panel with different parameters to create a new user like as shown below.

If you observe above picture, we have a section called Tags. Here, Tags are the rights or privileges which we assigned while creating a user and we can set single or multiple privileges to a user based on our requirements. In case, if we want to multiple privileges, then set privileges as a comma (,) separated like administrator, management, etc. based on our requirements.

Following are the different type of privileges or rights which supported in management plugin while creating a new user in RabbitMQ.

Tag	Description
management	If we set this tag, the user can access management plugin.
policymaker	If we set this tag, the user can access management plugin and manage policies and parameters for the vhosts they have access to.
monitoring	If we set this tag, the user can access management plugin and see all the connections and channels as well as node-related information.
administrator	If we set this tag, the user can do everything in management like manage users, vhosts, permissions, close other user's connections, and manage policies and parameters for all vhosts.

After adding a user, you can see all the users in All users panel for that just expand it like as shown below.

      8. RabbitMQ Set Privileges to Access Virtual Hosts. 

To set a permission to access virtual hosts, just click on the username which we have created “adminuser” and go to Permissions panel which is just below to overview panel and click on Set permission button to set permissions like as shown below.

Now we will use newly created user (“adminuser”) details to login into RabbitMQ web management. Following is the snapshot of RabbitMQ web management plugin after logging with new user “adminuser”.

      9. Automatic Synchronization.

 rabbitmqctl set_policy ha-fed \

".*" '{"federation-upstream-set":"all", "ha-sync-mode":"automatic", "ha-mode":"nodes", "ha-params":["rabbit@rabbitmq-0.rabbitmq.rabbits.svc.cluster.local","rabbit@rabbitmq-1.rabbitmq.rabbits.svc.cluster.local","rabbit@rabbitmq-2.rabbitmq.rabbits.svc.cluster.local"]}' \
    --priority 1 \
    --apply-to queues

     For more details

Summary

In this tutorial, you learned how to quickly deploy a RabbitMQ Cluster on kubernetes or OpenShift using yaml files. You have also gained access to the RabbitMQ management create new admin user and assign user privilege.