JS7 JobScheduler

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Table of Contents

Introduction

  • JS7 can be set up using for use with a Kubernetes cluster on a ServerCluster. Using the Linux - based JS7 images for Docker® containers which ship with a current Alpine base image and OpenJDK. components
    • products can be found
    in the articles listed below.
  • Users deploy JS7 products You can run an application by creating a Kubernetes Deployment object, and you can describe a Deployment in a deployment object from a deployment YAML file. To do so we need
    • To this purpose users have to first install and set up the Kubernetes
    cluster, once it is completed you can use the deployment YAML files to deploy JS7.

Setting up a Kubernetes Cluster

There are several ways how to set up a Kubernetes Cluster. Find an example from the following chapters.

The basic step which can be followed to install the Kubernetes cluster on Centos are:

...

Install Docker on all CentOS 7 VMs

  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 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 CentOS 7

    Code Block
    sudo yum install docker-ce

  5. A successful installation output will be concluded with a 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 correct, accept it.

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

  6. Manage Docker service
    Now Docker is installed, but the service is not yet running. Start and enable Docker using the commands. 

    Code Block
    sudo systemctl start docker
sudo systemctl enable docker

  7. To confirm that Docker is active and running, use:

    Code Block
    sudo systemctl status docker

Set up the Kubernetes Repository

...

Since the Kubernetes packages aren’t present in the official CentOS 7 repositories, we will need 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

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.

Deployment Files

The YAML sample files for deployment to

...

Install Kubelet on CentOS 7

  1. The first core module that we need to install on every node is Kubelet. Use the following command to do so:

    Code Block
    sudo yum install -y kubelet

Install kubeadm and kubectl on CentOS 7

kubeadm, the next core module, which has to be installed. Use the following command:

Code Block
sudo yum install -y kubeadm

(Note that kubeadm automatically installs kubectl as a dependency)

...

Disable swap

  1. For Kubelet to work, we also need to disable swap. The swap can be disabled using 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 kubeadm directly, then the kubeadm throws 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 delete the config.tomal file and restart contained using the below steps:

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

  3. Initialize Kubeadm and Create required directories and start managing Kubernetes cluster

    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 and Kubernetes services.

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

  5. Set up Pod network for the Cluster.

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

Following the above steps, the setup of the Kubernetes cluster is successful. Now you can create the Kubernetes YAML files and deploy 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:archive file: js7-kubernetes.zip

The archive includes the following files.

Deployment of JS7 Products: js7-deployment.yaml

...

Code Block
languageyml
titleExample for js7-deployment.yaml
linenumbers

...

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

...

"
      
  - 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
    env:
    - name: RUN_JS_JAVA_OPTIONS
      value: "-Xmx256m"
    - name: RUN_JS_USER_ID
      value:  "0:0"


The YAML file describes a single Pod for deployment to Kubernetes which is a group of one or more containers and a ConfigMap. The Pod includes three containers:

  1. The js7joc container runs thejoc-2-5-1image and exposes port 4446. It uses a ConfigMap with the name hibernate-config to specify a volume mounted to the /var/sos-berlin.com/js7/joc/resources/joc directory. The deployment file specifies a number of environment variables, including RUN_JS_JAVA_OPTIONS, RUN_JS_USER_ID, and RUN_JS_ID.
  2. The js7con container runs the controller-2-5-1 image and exposes port 4444. It sets the environment variables RUN_JS_JAVA_OPTIONS, RUN_JS_USER_ID, and RUN_JS_ID.
  3. The js7agent container runs the agent-2-5-1 image and exposes port 4445. It sets the environment variables RUN_JS_JAVA_OPTIONS, RUN_JS_USER_ID, and RUN_JS_ID.

The following implications apply:

  • Each container runs a different image from the sosberlin/js7 repository and is assigned a unique port.

  • Each container defines environment variables which control a number of runtime parameters for the application such as:

    • RUN_JS_JAVA_OPTIONS : see JS7 - FAQ - Which Java Options are recommended
    • RUN_JS_USER_ID: specifies the numeric User ID and Group ID - separated by a colon - of the run-time account used for the related JS7 product. A value 0:0 indicates the root account and root group, a value 1000:1000 specifies a user account with the given User ID and Group ID. For details see JS7 - Running Containers for User Accounts.
    • RUN_JS_ID: specifies the Controller ID which is a unique identifier for a Standalone Controller or Controller Cluster.

  • For the js7joc container the volumeMounts element specifies the hibernate-config ConfigMap which is mounted to the /var/sos-berlin.com/js7/joc/resources/joc directory.

Configuration for Port Forwarding: js7-service.yaml

...

Code Block
languageyml
titleExample for js7-service.yaml
linenumbers

...

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: {}

Hibernate Configuration: hibernate.cfg.xml

...

This

...

file includes the Hibernate configuration for connections to the JS7 - Database. Find the following example for use with a MySQL® database:

Code Block
languageyml
titleExample for js7-service.yaml
linenumbers

...

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>

Step-by-Step Instructions

To operate JOC Cockpit in a Kubernetes Cluster with the JS7 database users To make the Kubernetes cluster run according to your database environment, you can adjust the hibernate.cfg.xml file with your database credentials. The default file is MySql. You can use the hibernate.cfg.xml files of the other database from JS7 - Database.
The zip file, including the above configuration files, is that specifies the database connection and that holds credentials for database access. Find further examples from the JS7 - Database article.

  1. Download the archive file: js7-kubernetes.zip.

...

  1.  Open a console window from the directory where you downloaded the .zip archive and extract the archive.

  2. Execute the below command to create a ConfigMap and to pass the

    Open CMD from the folder where you unzip the attached ZIP.  

    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.

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



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

    Code Block
    kubectl create -f js7-deployment.yaml



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

    Code Block
    kubectl create -f js7-service.yaml



  5. Once both the YAML files are executed successfully, you users can get check the podPods' s status. The Kubectl Get Pod is a following command that displays the pods Pods running in the Kubernetes clusterCluster.

    Code Block
    kubectl get pods



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

    Code Block
    kubectl describe pods



  7. To The following command can be executed to check the IP address and Port of the running JOC Cockpit, execute the kubectl get service commandport of JS7 products.

    Code Block
    kubectl get service

Further Resources