Version: Mosquitto 2.8

High Availability

To set up a multi-node-HA Mosquitto broker and Management Center using Helm charts, you'll first need a Kubernetes environment. For deploying a full fledged kubernetes cluster on multiple hosts, Kubeadm is an excellent choice. Kubeadm is a command-line tool in the Kubernetes ecosystem designed to facilitate the process of setting up and bootstrapping a Kubernetes cluster (Discussed in Introduction section). This setup would deploy a 3 Mosquitto broker as a statefulsets. Also, a Management-Center pod and HA-proxy pod as a deployment entity. All the deployment would be deployed on multiple hosts. This deployment by default uses a NFS server to mount volumes. You would need to setup the NFS server before using this deployment.

Recommended Setup

1 Control-plane node, 3 worker nodes and a NFS Server.
Management center (MMC) is configured to have a node affinity that means the pod for MMC will spawn on a specific worker node. The default configuration expects names of the worker nodes to be node-1 ,node-2 and node-3 Given the nodes are named in similar fashion, MMC would be spawned on node-1.
If you want to have different names for your nodes you can also do that. You will have to adjust the hostnames of nodes in helm chart so that the MMC node affinity remains intact. To adjust the helm chart you will have to uncompress the helm charts and change the hostnames entries of values.yaml. You can do so using the following command:
- tar -xzvf mosquitto-multi-node-multi-host-0.1.0.tgz
- cd mosquitto-multi-node-multi-host
- Change the values of hostname from node-1/node-2/node-3 to the names of your machines. For eg, node-1,node-2 and node-3 can be renamed as worker-node-1,worker-node-2 and worker-node-3. Doing this, MMC would now be spawned on the node named worker-node-1.
- Go back to the parent directory: cd ../
- Package the helm chart to its original form using: helm package mosquitto-multi-node-multi-host

HA-PROXY Configurations HA-proxy need to be configured accordingly for the kubernetes setup. For server m1, m2 and m3 needs to be configured in this case. Instead of using docker IP we would use DNS names to address the pods. For eg mosquitto-0.mosquitto.multinode.svc.cluster.local. Here mosquitto-0,mosquitto-1,mosquitto-2 are the name of individual mosquitto pods running as statefulsets. Each new pod would increase its pod-ordinal by 1. Rest can be defined as follows <pod-name>.<name-of-the-statefulset>.<namespace>.svc.cluster.local

Your setup folder comes along with a default configuration of haproxy config which is given below. This assumes that your using namespace name as "multinode". You can also change the namespace name if you want and the procedure to do it would be discussed at a later stage.

global
    daemon
    maxconn 4096

frontend mqtt_frontend
    bind *:1883
    mode tcp
    default_backend mqtt_backend
    timeout client 10m

backend mqtt_backend
    timeout connect 5000
    timeout server 10m
    mode tcp
    option redispatch
    server m1 mosquitto-0.mosquitto.multinode.svc.cluster.local:1883 check on-marked-down shutdown-sessions
    server m2 mosquitto-1.mosquitto.multinode.svc.cluster.local:1883 check on-marked-down shutdown-sessions
    server m3 mosquitto-2.mosquitto.multinode.svc.cluster.local:1883 check on-marked-down shutdown-sessions

Note: Make sure to add more entries to this haproxy.cfg file if you wish to add nodes to this cluster. You would have to reconfigure the HACONFIG in that case.

Kubernetes Cluster Setup

Dependencies and Prerequisites

Docker
Kubernetes Cluster with Kubeadm
Helm

If you need to set up a Kubernetes cluster, you can refer to our installation script. If you plan on using your own cluster, you can skip to step 5. Follow these steps on your master/control-plane node :

Setup the ha-cluster setups folder:
- Copy or setup the mosquitto-2.8-mmc-2.8-cluster-kubernetes folder to the Control-Plane node. Also make sure to create a directory inside the copied folder on Control-Plane node named license that contains the license.lic file we provided you. So the relative path would be mosquitto-2.8-mmc-2.8-cluster-kubernetes/license/license.lic.
Choose Architecture Folder:
- Depending on your host architecture, navigate to the corresponding folder:
  - For Debian AMD64:
    cd mosquitto-2.7-mmc-2.7-cluster-kubernetes/kubernetes/multi-node-multi-host/debian_amd64
Install Common Dependencies:
- Run the following command to install the necessary dependencies on all the nodes(including control-plane node):
```
bash common-installation-debian.sh
```
Install Master Dependencies:
- Run the following command to install the necessary dependencies only on the master node (i.e control-plane node):
```
bash  master-installation-debian.sh
```
Create a namespace
- On your Control-Plane node: Create a namespace in which you would want to deploy the application. The deployment folder is pre-configured for the namespace named multinode. If you want to use the default configuration you can create a namespace named multinode using the below command:
- kubectl create namespace multinode
- If you want to use a different namespace, use the command: kubectl create namespace <your-custom-namespace>. Replace <your-custom-namespace> with the name of the namespace you want to configure.
Create configmap for your license
- On your Control-Plane node: Create a configmap for your license key. You can create the configmap using the following command:
- kubectl create configmap mosquitto-license -n <namespace> --from-file=<path-to-your-license-file>
- Make sure the name of the configmap remains the same as mosquitto-license as this is required by the deployment files and statefulsets.
- A sample configmap creation command would look something like this if the choosen namespace is multinode and the license file is at the path /root/mosquitto-2.8-mmc-2.8-cluster-kubernetes/license/license.lic :
  - kubectl create configmap mosquitto-license -n multinode --from-file=/root/mosquitto-2.8-mmc-2.8-cluster-kubernetes/license/license.lic
Setup NFS Server
- On your NFS-Server : Copy or setup the mosquitto-2.8-mmc-2.8-cluster-kubernetes folder to the NFS-Server.
- Install necessary dependencies sudo apt-get update sudo apt-get install nfs-kernel-server
- Configure exports directory. Open the /etc/exports file on NFS-server. Expose the directories so that pods running on other worker nodes can access these directories and mount the volumes.
  - The default starting point of the cluster is with 3 Mosquitto broker nodes, however we will configure and expose a total of 6 Mosquitto data directories along with a MMC config directory in the NFS server. As the provisioning of data directories on the NFS servers are not dynamic at the moment for On-premise setup, configuring three extra Mosquitto data directories makes the job easier later when you want to add further nodes.
  - The helm charts therefore is also configured in a fashion that they create total of 7 persistent volumes and persistent volume claims (6 for Mosquitto data directories and 1 for MMC). However, only three Mosquitto broker would be spinned up by default.
  - You can use the following as a reference. Here we expose six Mosquitto nodes and management center. The actual path to your mosquitto-2.8-mmc-2.8-cluster-kubernetes folder may differ.
    /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server1/mosquitto/data *(rw,sync,no_root_squash,no_subtree_check) /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server2/mosquitto/data *(rw,sync,no_root_squash,no_subtree_check) /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server3/mosquitto/data *(rw,sync,no_root_squash,no_subtree_check) /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server4/mosquitto/data *(rw,sync,no_root_squash,no_subtree_check) /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server5/mosquitto/data *(rw,sync,no_root_squash,no_subtree_check) /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server6/mosquitto/data *(rw,sync,no_root_squash,no_subtree_check) /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server1/management-center/config *(rw,sync,no_root_squash,no_subtree_check)
- Make sure all the data directories have adequate privileges so that mosquitto kubernetes pods can create additional directories inside these data directories. We provide 1000 ownership to all the data directory of mosquitto servers and root ownership to config of management-center. The same ownership are also the default ownership of mosquitto pods and MMC pods.
```
sudo chown -R 1000:1000 /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server1/mosquitto/data
sudo chown -R 1000:1000 /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server2/mosquitto/data
sudo chown -R 1000:1000 /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server3/mosquitto/data
sudo chown -R 1000:1000 /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server4/mosquitto/data
sudo chown -R 1000:1000 /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server5/mosquitto/data
sudo chown -R 1000:1000 /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server6/mosquitto/data
sudo chown -R root:root /home/<user>/mosquitto-2.8-mmc-2.8-cluster-kubernetes/server1/management-center/config
```
- Note: We provide ownership of 1000 as mosquitto kubernetes pods uses user id of 1000 by default and root to MMC pods.
- Expose the directories using: sudo exportfs -a
- Restart the kernel-server. sudo systemctl restart nfs-kernel-server
- Install necessary "nfs-common" library on other nodes (Control-plane and worker nodes) so that they act as nfs-clients: sudo apt-get install nfs-common

Installation

Prerequisites:

Kubernetes Cluster should be up and running. If you are yet to setup the cluster, refer Kubernetes Cluster Setup.
You have configured your NFS Server by exposing the directories.
You have successfully created the namespace and configmap for your license (i.e mosquitto-license).

Once kubernetes cluster is up and running then you can now follow these steps to install the multi-node Mosquitto broker setup:

Installation using Helm Charts:

Helm charts offer a comprehensive solution for configuring various Kubernetes resources—including stateful sets, deployment templates, services, and service accounts—through a single command, streamlining the deployment process.

Setup the folder on your Control-Plane node:
- Make sure you have the mosquitto-2.8-mmc-2.8-cluster-kubernetes folder on the Control Plane node.
Change Directory:
- Navigate to the project directory (i.e multi-node-multi-host). cd mosquitto-2.8-mmc-2.8-cluster-kubernetes/kubernetes/multi-node-multi-host/
Install Helm Chart:
- Use the following helm install command to deploy the Mosquitto application on to your Kubernetes cluster. Replace <release-name> with the desired name for your Helm release and <namespace> with your chosen Kubernetes namespace:
```
helm install <release-name>  mosquitto-multi-node-multi-host-0.1.0.tgz   --set repoPath=<root-path-to-kubernetes-folder> --set nfs=<your-nfs-ip> -n <namespace>  --set imageCredentials.registry=registry.cedalo.com --set imageCredentials.username=<username> --set imageCredentials.password=<password> --set imageCredentials.email=<email>
```
- repoPath: Set the repoPath flag to the path where the folder mosquitto-2.8-mmc-2.8-cluster-kubernetes resides on NFS server. For eg if it exists on /root/mosquitto-2.8-mmc-2.8-cluster-kubernetes therefore the repoPath would be /root and if exists on /home/demo/mosquitto-2.8-mmc-2.8-cluster-kubernetes then the repoPath would be /home/demo.
- namespace: Set it to the namespace of your deployment.
- Note: If you want to deploy the setup in a different namespace other than multinode, make sure to pass a separate flag --set namespace=<your-custom-namespace> along with the helm installation command.
- Note: You need to configure the IP of your NFS server by passing --set nfs=<your-nfs-ip> along with the helm installation command. Make sure you use the internal NFS ip accessible from within the Kubernetes cluster and not the external IP exposed to the internet (in case you have one).
- imageCredentials.username: Your docker username provided by Cedalo team.
- imageCredentials.password: Your docker password provided by Cedalo team.
- imageCredentials.email: Registered e-mail for accessing docker registry.
- Sample example: If your NFS IP is 10.10.10.10, mosquitto-2.8-mmc-2.8-cluster-kubernetes resides at the location /root on your nfs, your name namespace is test-namespace and your arbitrary release name is sample-release-name, username, password and email be demo-username, demo-password and demo@gmail.com then your helm installation command should be:
```
   helm install sample-release-name  mosquitto-multi-node-multi-host-0.1.0.tgz   --set repoPath=/root  -n test-namespace --set namespace=test-namespace --set nfs=10.10.10.10 --set imageCredentials.registry=registry.cedalo.com --set imageCredentials.username=demo-username --set imageCredentials.password=demo-password --set imageCredentials.email=demo@gmail.com
```
You can monitor the running pods using the kubectl get pods -o wide -n <namespace> command. To observe the opened ports use kubectl get svc -n <namespace>.
To uninstall the setup: helm uninstall <release-name> -n <namespace>

Your Mosquitto setup is now running with three single mosquitto nodes and the Management Center. To finish the cluster setup, the Management Center offers a UI to create the Mosquitto HA Cluster. The Management Center is reachable from the localhost via port 31021.

To set up the cluster follow these steps.

Further possible Configurations

Add Nodes
- Configure your HA-proxy by adding entries to the haproxy.cfg.
- haconfig configmap is part of the compressed Helm chart. Therefore, to edit the configmap, uncompress the helm chart using the following command:
  - tar -xzvf mosquitto-multi-node-multi-host-0.1.0.tgz
  - cd mosquitto-multi-node-multi-host/templates/
  - Edit haconfig.yaml by adding below mentioned line at end the the file server m4 mosquitto-3.mosquitto.<namespace>.svc.cluster.local:1883 check on-marked-down shutdown-sessions. Replace <namespace> with your chosen namespace. This config line assumes you are adding the fourth node.
- Go back to the parent directory: cd ../
- Package the helm chart to its original form using: helm package mosquitto-multi-node-multi-host
- Uninstall helm package helm uninstall <release-name> -n <namespace>
- You can also upgrade the existing setup using helm upgradehelm upgrade <release-name> -n <namespace>
- We do not need to configure extra data directories in the NFS server till we exceed the count of 6 Mosquitto brokers as we already addressed this while configuring our NFS server.
- Reinstall helm package if you used helm uninstall instead of helm upgrade, so that new configmaps can come into effect (Use the same command you used to install it the first time with appropriate flags. Below command eg is just a reference)
```
   helm install sample-release-name  mosquitto-multi-node-multi-host-0.1.0.tgz   --set repoPath=/root  -n test-namespace --set namespace=test-namespace --set nfs=10.10.10.10 --set imageCredentials.registry=registry.cedalo.com --set imageCredentials.username=demo-username --set imageCredentials.password=demo-password --set imageCredentials.email=demo@gmail.com
```
- In order to scale the number of pods from the existing three mosquitto pods, you can scale the Kubernetes replica count of statefulset to desired number. For eg if you want to increase the number of nodes from default three nodes to four nodes you can use the following command: Kubectl scale statefulsets mosquitto --replicas=4 -n <namespace>
- You can now add the broker connections and the additional nodes in the cluster through Management-center.
  - Open your MMC, navigate to broker connections, click on NEW CONNECTION .
  - Fill in the details like ID(make sure it does not conflict with the existing ones), NAME: name of the connection (you can choose your own name).
  - URL: mqtt://mosquitto-x.mosquitto.<namespace>.svc.cluster.local:1885 . Replace x in mosquitto-x with a valid number based on the which node you are adding. If you are adding a fourth node and the name of your namespace is multinode then the entry would be mqtt://mosquitto-3.mosquitto.multinode.svc.cluster.local:1885.
  - Add your username and password given by the cedalo team, select/deselect further options and click CONNECT & SAVE.
- Adding new node to existing cluster:
  - Navigate to Cluster Management and select your existing cluster.
  - Click Edit and select Add Node.
  - Enter DNS address in IP address field. For eg mosquitto-x.mosquitto.<namespace>.svc.cluster.local. Replace x in mosquitto-x with a valid number based on the which node you are adding. If you are adding a fourth node and the name of your namespace is multinode then the entry would be mosquitto-3.mosquitto.multinode.svc.cluster.local.
    - Select Add Node and click Save.
Remove Nodes
- You can start by removing the node configuration from the existing cluster using the Management Center.
- You can now remove the broker connections using the Management Center.
- Then you can set the replica count to desired number. For eg if you want to decrease the number of nodes from four nodes to three nodes you can use the following command. kubectl scale statefulsets mosquitto --replicas=3 -n <namespace>
Further Useful Commands
- If you want to change mosquitto.conf, you can do so by uncompressing the helm chart, making the required changes and packaging the helm charts again. The detailed procedure is mentioned below:
  - tar -xzvf mosquitto-multi-node-multi-host-0.1.0.tgz
  - cd mosquitto-multi-node-multi-host/files/
  - Make changes to mosquitto.conf and save it.
  - Go back to the parent directory: cd ../
  - Package the helm chart to its original form using: helm package mosquitto-multi-node-multi-host
  - Uninstall helm package helm uninstall <release-name> -n <namespace>
  - Reinstall the helm package using the same command you used the first time from the mosquitto-2.8-mmc-2.8-cluster-kubernetes/kubernetes/multi-node-multi-host/ directory.

Create Cluster in Management Center

After you have completed the installation process, the last step is to configure the Mosquitto HA cluster. Access the Management Center and use the default credentials cedalo and password mmcisawesome.

Make sure all three mosquitto nodes are connected in the connection menu. The HA proxy will only connect after the cluster is successfully set up.
Navigate to Cluster Management and click NEW CLUSTER.
Configure Name, Description and choose between Full-sync and Dynamic Security Sync.
Configure IP address: Instead of private IP address we will use DNS address.
- For node1: mosquitto-0.mosquitto.multinode.svc.cluster.local and select broker2 from drop-down
- For node2: mosquitto-1.mosquitto.multinode.svc.cluster.local and select broker2 from drop-down
- For node3: mosquitto-2.mosquitto.multinode.svc.cluster.local and select broker3 from drop-down
  - Replace "multinode" with your own namespace. If you have used the default one, use the mentioned configurations.
  - mosquitto-0 has to be mapped to the mosquitto-1 node in the MMC UI and so on.
Click Save

Connect to cluster

After the creation of the cluster, you can now select the cluster leader in the drop-down in the top right side of the MMC. This is needed, because only the leader is able to configure the cluster. The drop-down appears as soon as you are in one of the broker menus. Go to the "Client" menu and create a new client to connect from. Make sure to assign a role, like the default "client" role, to allow your client to publish and/or subscribe to topics. Now you can connect to the Mosquitto cluster. You can access it either with connecting it directly to worker node running the haproxy pod along with a service exposed at port 31028:

In this example command we use Mosquitto Sub to subscribe onto all topics: mosquitto_sub -h <ip-of-the-worker-node-running-haproxy> -p 31028 -u <username> -P <password> -t '#'

or if you have an load balancer in front of it redirecting the traffic to HAproxy the we can use the ip of the load balancer (mostly for the setup running on Cloud VMs): mosquitto_sub -h <ip-of-the-load-balancer-running-haproxy> -p 31028 -u <username> -P <password> -t '#'

Make sure to replace your IP, username and password.

Usage

Once the installation is complete, you can start using the multi-node Mosquitto broker. Be sure to check the Mosquitto documentation for further details on configuring and using the broker

Kubernetes Cluster Setup​

Dependencies and Prerequisites​

Installation​

Installation using Helm Charts:​

Further possible Configurations​

Create Cluster in Management Center​

Connect to cluster​

Usage​