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Introduction

• JS7 can be set up using for use with a Kubernetes cluster on a Server. Using the Linux - based JS7 images for Docker® containers which ship with a current Alpine base image and OpenJDK.
  • Docker® images for JS7 are publicly available from https://hub.docker.com/r/sosberlin/js7.
  • Instructions on how to run containers for JS7 components can be found
  in the articles listed below.
  • from the JS7 - Installation for Docker Containers article series.
• Users deploy JS7 components You can run an application by creating a Kubernetes Deployment object, and you can describe a Deployment in a YAML file. To do so we need to first install and set up the Kubernetes cluster, once it is completed you can use the deployment YAML files to deploy JS7.

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• deployment object from a deployment YAML file, for details see JS7 - How to deploy to a Kubernetes Cluster

There are several ways how to set up a Kubernetes Clustercluster. Find an example for the basic steps to install a Kubernetes cluster on CentOS  7 from the following chapters.The basic step which can be followed to install the Kubernetes cluster on Centos are:

Setting up a Kubernetes Cluster

Install Docker on

...

CentOS 7

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1. Update the package database

   Code Block
   sudo yum check-update

2. Install the dependencies

   Code Block
   sudo yum install -y yum-utils device-mapper-persistent-data lvm2

3. Add and enable the

   official

   Docker Repository

   to

   for CentOS

   7

   Code Block
   sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

4. Install the latest Docker version

   on

   for CentOS

   7

   Code Block
   sudo yum install docker-ce

5. A

   After successful installation the output will

   be concluded with a

   include the string  Complete!
You may be prompted to accept the GPG key. This is to verify that the fingerprint matches.

   The format will look as follows. If

   A fingerprint can look like this, if you consider the fingerprint being correct, accept it

   .

   :

   Code Block
   060A 61C5 1B55 8A7F 742B 77AA C52F EB6B 621E 9F35

6. Manage Docker service
   

   Now

   With Docker

   is

   being installed

   , but

   the

   service is not yet running

   systemd service has to be started. Start and enable Docker from systemd using the following commands

   . 

   :
   

   Code Block
   sudo systemctl start docker sudo systemctl enable docker

7. To

   confirm

   check that Docker is

   active

   up and running

   ,

   use the command:
   

   Code Block
   sudo systemctl status docker

Set up the Kubernetes Repository

1. Since the Kubernetes packages aren’t present in the official CentOS 7 repositories

   , we will need

   users have to add a new repository file. Use the following command to create the file and open it for editing:
   

   Code Block
   sudo vi /etc/yum.repos.d/kubernetes.repo

2. Once the file is open, press the I key to enter insert mode and paste the following contents:
   

   Code Block
   [kubernetes] name=Kubernetes baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64 enabled=1 gpgcheck=1 repo_gpgcheck=1 gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg

   Once pasted, press escape to exit insert mode. Then enter :x to save the file and exit.

Install

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kubelet on CentOS 7

...

kubelet is the first core module

...

to

...

be installed on every Kubernetes cluster node

...

. Use the following command

...

:

sudo yum install -y kubelet

Install kubeadm and kubectl on CentOS 7

1. kubeadm

   ,

   is the next core module

   , which

   that has to be installed. Use the following command:

   Code Block
   sudo yum install -y kubeadm

   (

   Note that kubeadm automatically installs kubectl as a dependency

   )

   .

   
   

2. Disable swap

   For Kubelet to work, we also need to disable swap. The swap can be disabled using

   by use of the below commands:
   

   Code Block
   sudo swapoff -a sudo sed -i '/ swap / s/^/#/' /etc/fstab

Initialize

...

kubeadm and start the Kubernetes cluster

1. When

   we initialize the

   initializing kubeadm directly

   ,

   then

   the

   kubeadm

   throws

   might raise the error:

   Code Block
   Some fatal errors occurred: [ERROR CRI]: container runtime is not running Status from runtime service failed” err=”rpc error: code = Unimplemented desc = unknown service runtime.v1alpha2.RuntimeService”

2. To resolve the above

   error, it is required to

   problem users should delete the config.tomal file and restart

   contained

   containerd using the

   below steps

   following commands:
   

   Code Block
   sudo rm /etc/containerd/config.toml systemctl restart containerd

3. Initialize

   Kubeadm and Create

   kubeadm, create required directories and

   start managing

   manage Kubernetes cluster configuration:

   Code Block
   sudo kubeadm init mkdir $HOME/.kube sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config sudo chown $(id -u):$(id -g) $HOME/.kube/config export KUBECONFIG=/etc/kubernetes/admin.conf

4. Enable and restart

   docker

   Docker and Kubernetes services from systemd.

   Code Block
   sudo systemctl enable docker.service sudo service kubelet restart sudo chown -R centos:centos kubernetes/

5. Set up

   Pod

   pod network for the

   Cluster

   Kubernetes cluster.

   Code Block
   kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/2140ac876ef134e0ed5af15c65e414cf26827915/Documentation/kube-flannel.yml kubectl get nodes

Following With the above steps , the setup of the Kubernetes cluster is successful. Now you completed. In a next step users can create the Kubernetes YAML files and to deploy JS7 components to the JS7 on this Kubernetes cluster.

Deploying JS7 on Kubernetes

The example YAML files of Kubernetes are attached to the article.

Download the attached zip file. The folder structure includes three files:

1. 1. js7-deployment.yaml – This file is the deployment file for the JS7

      Code Block
      language yml title Example js7-deployment.yaml linenumbers true collapse true
      apiVersion: v1 kind: Pod metadata: creationTimestamp: null labels: run: js7joc name: js7joc spec: volumes: - name: hibernate-config configMap: name: hibernate-config containers: - image: sosberlin/js7:joc-2-5-1 name: js7joc ports: - containerPort: 4446 volumeMounts: - name: hibernate-config mountPath: /var/sos-berlin.com/js7/joc/resources/joc/ env: - name: RUN_JS_JAVA_OPTIONS value: "-Xmx256m" - name: RUN_JS_USER_ID value: "0:0" - name: RUN_JS_ID value: "jobscheduler" - image: sosberlin/js7:controller-2-5-1 name: js7con ports: - containerPort: 4444 env: - name: RUN_JS_JAVA_OPTIONS value: "-Xmx256m" - name: RUN_JS_USER_ID value: "0:0" - name: RUN_JS_ID value: "jobscheduler" - image: sosberlin/js7:agent-2-5-1 name: js7agent ports: - containerPort: 4445

   2. js7-service.yaml – This includes the configuration of port forwarding

      Code Block
      language yml title Example js7-service.yaml linenumbers true collapse true
      apiVersion: v1 kind: Service metadata: creationTimestamp: null labels: run: js7joc name: js7joc spec: ports: - name: js7joc port: 4446 protocol: TCP targetPort: 4446 - name: js7agent port: 4445 protocol: TCP targetPort: 4445 - name: js7controller port: 4444 protocol: TCP targetPort: 4444 selector: run: js7joc type: LoadBalancer status: loadBalancer: {}

   3. hibernate.cfg.xml – This is the hibernate file for connection to the database.

      Code Block
      language yml title Example js7-service.yaml linenumbers true collapse true
      <?xml version="1.0" encoding="UTF-8" standalone="no"?> <hibernate-configuration> <session-factory> <property name="hibernate.connection.driver_class">org.mysql.jdbc.Driver</property> <property name="hibernate.connection.password">jobscheduler</property> <property name="hibernate.connection.url">jdbc:mysql://mysqlsrv:3306/jobscheduler</property> <property name="hibernate.connection.username">jobscheduler</property> <property name="hibernate.dialect">org.hibernate.dialect.MySQLInnoDBDialect</property> <property name="hibernate.show_sql">false</property> <property name="hibernate.connection.autocommit">false</property> <property name="hibernate.format_sql">true</property> <property name="hibernate.temp.use_jdbc_metadata_defaults">false</property> <property name="hibernate.connection.provider_class">org.hibernate.hikaricp.internal.HikariCPConnectionProvider</property> <property name="hibernate.hikari.maximumPoolSize">10</property> </session-factory> </hibernate-configuration>

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The zip file, including the above configuration files, is js7-kubernetes.zip. After downloading the attached file, follow the below steps to deploy the container:

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Further Resources

• JS7 - How to deploy to a Kubernetes Cluster

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To create a config map and pass the and to pass this hibernate.cfg.xml file to the mount directory of the container, follow the below command.

kubectl create configmap hibernate-config --from-file=hibernate.cfg.xml

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To create the service of the JS7 configuration, you need to run the js7-service.yaml file:

kubectl create -f js7-deployment.yaml

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To create the deployment of the JS7 configuration, you need to run the js7-deployment.yaml file:

kubectl create -f js7-service.yaml

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Once both the YAML files are executed successfully, you can get the pod's status. The Kubectl Get Pod is a command that displays the pods running in the Kubernetes cluster.

kubectl get pods

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Once both the YAML files are executed successfully, you can describe Pod and check each step in the YAML file is executed successfully or not. The Kubectl Describe Pod is a command that describes any resource in Kubernetes. It shows data on a single or even a collection of resources.

kubectl describe pods

To check the IP and Port of the running JOC Cockpit, execute the kubectl get service command.

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