Use JNDI to share objects between different virtual machines

Before I turn to this month’s tool, I would like to address feedback from my previous article. I’ll respond to reader comments on better design, performance problems, and bugs.

Better design

One reader commented that the Cachetable I presented in last month’s column violates the Liskov Substitution Principle (see Resources). This principle basically states that if B is a subclass of A, and C is a subclass of A, then B should be able to subclass C without any problems, and vice versa. In other words, any class that currently extends Hashtable should be able to also extend Cachetable without any side-effects. It wasn’t my original intention to support this notion, but the reader is correct in asserting that it is good object-oriented design.

To read this article in full, please click here

JavaWorld Cool Tools

gamingdirectional: The mana detection mechanism

Finally, in this chapter, we will look at the mana detection mechanism where when the player has overlapped mana he will gain 1 unit of life so when he hits the enemy he can continue to move onward after he has used that 1 unit of life to heal himself. We will also remove the enemy from the scene after it has collided with the player. In order to create such a system, we need to edit a few files.


Planet Python

PyCharm: PyCharm 2019.1 EAP 6

A variable viewer for our native Jupyter Notebook support, an interpreter indicator in the status bar, and more. Try the PyCharm 2019.1 EAP now, you can download the latest version on our website.

New in This Version

Variable Viewer for Jupyter Notebooks

Notebooks Variable

Last week we’ve introduced our new Jupyter Notebooks support, that allows you to directly edit and run .ipynb files from PyCharm. This week, we’re adding some more functionality.

Have you ever lost track of the state of your Jupyter Notebook as you’re working with it? We’ve now added a variables viewer to our new Jupyter Notebook support, so you can easily see what’s going on.

Interpreter Indicator

Interpreter Chooser

Are you in the process of migrating to a new version of a framework, or even a new version of Python? PyCharm now makes it even easier to switch between interpreters. Just choose it right from the status bar. If you prefer to keep your hands on your keyboard, use Ctrl+Shift+A to find action, and look for ‘Switch Python interpreter’.

Further Improvements


Download this EAP from our website. Alternatively, you can use the JetBrains Toolbox App to stay up to date throughout the entire EAP.

With PyCharm 2019.1 we’re moving to a new runtime environment: this EAP build already bundles the brand new JetBrains Runtime Environment (a customized version of JRE 11). Unfortunately, since this build uses the brand-new platform, the patch-update from previous versions is not available this time. Please use the full installation method instead.

If you tried 2019.1 EAP 3 or an earlier EAP of 2019.1: you may get an error about “MaxJavaStackTraceDepth=-1” when you start the IDE. If you get it, please remove that line from the custom JVM options. This is an incompatibility between the old JRE and the new one, and we apologize for any inconvenience.

If you’re on Ubuntu 16.04 or later, you can use snap to get PyCharm EAP, and stay up to date. You can find the installation instructions on our website.

PyCharm 2019.1 is in development during the EAP phase, therefore not all new features are already available. More features will be added in the coming weeks. As PyCharm 2019.1 is pre-release software, it is not as stable as the release versions. Furthermore, we may decide to change and/or drop certain features as the EAP progresses.

All EAP versions will ship with a built-in EAP license, which means that these versions are free to use for 30 days after the day that they are built. As EAPs are released weekly, you’ll be able to use PyCharm Professional Edition EAP for free for the duration of the EAP program, as long as you upgrade at least once every 30 days.

Planet Python

Webinar Series: Kubernetes Package Management with Helm and CI/CD with Jenkins X

Webinar Series

This article supplements a webinar series on doing CI/CD with Kubernetes. The series discusses how to take a cloud native approach to building, testing, and deploying applications, covering release management, cloud native tools, service meshes, and CI/CD tools that can be used with Kubernetes. It is designed to help developers and businesses that are interested in integrating CI/CD best practices with Kubernetes into their workflows.

This tutorial includes the concepts and commands from the second session of the series, Kubernetes Package Management with Helm and CI/CD with Jenkins X.

Warning: The procedures in this tutorial are meant for demonstration purposes only. As a result, they don’t follow the best practices and security measures necessary for a production-ready deployment.


In order to reduce error and organize complexity when deploying an application, CI/CD systems must include robust tooling for package management/deployment and pipelines with automated testing. But in modern production environments, the increased complexity of cloud-based infrastructure can present problems for putting together a reliable CI/CD environment. Two Kubernetes-specific tools developed to solve this problem are the Helm package manager and the Jenkins X pipeline automation tool.

Helm is a package manager specifically designed for Kubernetes, maintained by the Cloud Native Computing Foundation (CNCF) in collaboration with Microsoft, Google, Bitnami, and the Helm contributor community. At a high level, it accomplishes the same goals as Linux system package managers like APT or YUM: managing the installation of applications and dependencies behind the scenes and hiding the complexity from the user. But with Kubernetes, the need for this kind of management is even more pronounced: Installing applications requires the complex and tedious orchestration of YAML files, and upgrading or rolling back releases can be anywhere from difficult to impossible. In order to solve this problem, Helm runs on top of Kubernetes and packages applications into pre-configured resources called charts, which the user can manage with simple commands, making the process of sharing and managing applications more user-friendly.

Jenkins X is a CI/CD tool used to automate production pipelines and environments for Kubernetes. Using Docker images, Helm charts, and the Jenkins pipeline engine, Jenkins X can automatically manage releases and versions and promote applications between environments on GitHub.

In this second article of the CI/CD with Kubernetes series, you will preview these two tools by:

  • Managing, creating, and deploying Kubernetes packages with Helm.

  • Building a CI/CD pipeline with Jenkins X.

Though a variety of Kubernetes platforms can use Helm and Jenkins X, in this tutorial you will run a simulated Kubernetes cluster, set up in your local environment. To do this, you will use Minikube, a program that allows you to try out Kubernetes tools on your own machine without having to set up a true Kubernetes cluster.

By the end of this tutorial, you will have a basic understanding of how these Kubernetes-native tools can help you implement a CI/CD system for your cloud application.


To follow this tutorial, you will need:

  • An Ubuntu 16.04 server with 16 GB of RAM or above. Since this tutorial is meant for demonstration purposes only, commands are run from the root account. Note that the unrestrained privileges of this account do not adhere to production-ready best practices and could affect your system. For this reason, it is suggested to follow these steps in a test environment such as a virtual machine or a DigitalOcean Droplet.

  • A GitHub account and GitHub API token. Be sure to record this API token so that you can enter it during the Jenkins X portion of this tutorial.

  • Familiarity with Kubernetes concepts. Please refer to the article An Introduction to Kubernetes for more details.

Step 1 — Creating a Local Kubernetes Cluster with Minikube

Before setting up Minikube, you will have to install its dependencies, including the Kubernetes command line tool kubectl, the bidirectional data transfer relay socat, and the container program Docker.

First, make sure that your system’s package manager can access packages over HTTPS with apt-transport-https:

  • apt-get update
  • apt-get install apt-transport-https

Next, in order to ensure the kubectl download is valid, add the GPG key for the official Google repository to your system:

  • curl -s | apt-key add -

Once you have added the GPG key, create the file /etc/apt/sources.list.d/kubernetes.list by opening it in your text editor:

  • nano /etc/apt/sources.list.d/kubernetes.list

Once this file is open, add the following line:

deb kubernetes-xenial main 

This will show your system the source for downloading kubectl. Once you have added the line, save and exit the file. With the nano text editor, you can do this by pressing CTRL+X, typing y, and pressing ENTER.

Finally, update the source list for APT and install kubectl, socat, and

  • apt-get update
  • apt-get install -y kubectl socat

Note: For Minikube to simulate a Kubernetes cluster, you must download the package rather than the newer docker-ce release. For production-ready environments, docker-ce would be the more appropriate choice, since it is better maintained in the official Docker repository.

Now that you have installed kubectl, you can proceed with installing Minikube. First, use curl to download the program’s binary:

  • curl -Lo minikube

Next, change the access permissions of the file you just downloaded so that your system can execute it:

  • chmod +x minikube

Finally, copy the minikube file to the executable path at /usr/local/bin/ and remove the original file from your home directory:

  • cp minikube /usr/local/bin/
  • rm minikube

With Minikube installed on your machine, you can now start the program. To create a Minikube Kubernetes cluster, use the following command:

  • minikube start --vm-driver none

The flag --vm-driver none instructs Minikube to run Kubernetes on the local host using containers rather than a virtual machine. Running Minikube this way means that you do not need to download a VM driver, but also means that the Kubernetes API server will run insecurely as root.

Warning: Because the API server with root privileges will have unlimited access to the local host, it is not recommended to run Minikube using the none driver on personal workstations.

Now that you have started Minikube, check to make sure that your cluster is running with the following command:

  • minikube status

You will receive the following output, with your IP address in place of your_IP_address:

minikube: Running cluster: Running kubectl: Correctly Configured: pointing to minikube-vm at your_IP_address 

Now that you have set up your simulated Kubernetes cluster using Minikube, you can gain experience with Kubernetes package management by installing and configuring the Helm package manager on top of your cluster.

Step 2 — Setting Up the Helm Package Manager on your Cluster

In order to coordinate the installation of applications on your Kubernetes cluster, you will now install the Helm package manager. Helm consists of a helm client that runs outside the cluster and a tiller server that manages application releases from within the cluster. You will have to install and configure both to successfully run Helm on your cluster.

To install the Helm binaries, first use curl to download the following installation script from the official Helm GitHub repository into a new file named

  • curl >

Since this script requires root access, change the permission of so that the owner of the file (in this case, root) can read, write, and execute it:

  • chmod 700

Now, execute the script:

  • ./

When the script finishes, you will have helm installed to /usr/local/bin/helm and tiller installed to /usr/local/bin/tiller.

Though tiller is now installed, it does not yet have the correct roles and permissions to access the necessary resources in your Kubernetes cluster. To assign these roles and permissions to tiller, you will have to create a service account named tiller. In Kubernetes, a service account represents an identity for processes that run in a pod. After a process is authenticated through a service account, it can then contact the API server and access cluster resources. If a pod is not assigned a specific service account, it gets the default service account. You will also have to create a Role-Based access control (RBAC) rule that authorizes the tiller service account.

In Kubernetes RBAC API, a role contains rules that determine a set of permissions. A role can be defined with a scope of namespace or cluster, and can only grant access to resources within a single namespace. ClusterRole can create the same permissions on the level of a cluster, granting access to cluster-scoped resources like nodes and namespaced resources like pods. To assign the tiller service account the right role, create a YAML file called rbac_helm.yaml and open it in your text editor:

  • nano rbac_helm.yaml

Add the following lines to the file to configure the tiller service account:

apiVersion: v1 kind: ServiceAccount metadata:   name: tiller   namespace: kube-system --- apiVersion: kind: ClusterRoleBinding metadata:   name: tiller roleRef:   apiGroup:   kind: ClusterRole   name: cluster-admin subjects:   - kind: ServiceAccount     name: tiller     namespace: kube-system    - kind: User     name: "admin"     apiGroup:    - kind: User     name: "kubelet"     apiGroup:    - kind: Group     name: system:serviceaccounts     apiGroup: 

In the preceding file, ServiceAccount allows the tiller processes to access the apiserver as an authenticated service account. ClusterRole grants certain permissions to a role, and ClusterRoleBinding assigns that role to a list of subjects, including the tiller service account, the admin and kubelet users, and the system:serviceaccounts group.

Next, deploy the configuration in rbac_helm.yaml with the following command:

  • kubectl apply -f rbac_helm.yaml

With the tiller configuration deployed, you can now initialize Helm with the --service-acount flag to use the service account you just set up:

  • helm init --service-account tiller

You will receive the following output, representing a successful initialization:

Creating /root/.helm Creating /root/.helm/repository Creating /root/.helm/repository/cache Creating /root/.helm/repository/local Creating /root/.helm/plugins Creating /root/.helm/starters Creating /root/.helm/cache/archive Creating /root/.helm/repository/repositories.yaml Adding stable repo with URL: Adding local repo with URL: $ HELM_HOME has been configured at /root/.helm. Tiller (the Helm server-side component) has been installed into your Kubernetes Cluster. Please note: by default, Tiller is deployed with an insecure 'allow unauthenticated users' policy. To prevent this, run `helm init` with the --tiller-tls-verify flag. For more information on securing your installation see: Happy Helming!

This creates a tiller pod in the kube-system namespace. It also creates the .helm default repository in your $ HOME directory and configures the default Helm stable chart repository at and the local Helm repository at

To make sure that the tiller pod is running in the kube-system namespace, enter the following command:

  • kubectl --namespace kube-system get pods

In your list of pods, tiller-deploy will appear, as is shown in the following output:

NAME READY STATUS RESTARTS AGE etcd-minikube 1/1 Running 0 2h kube-addon-manager-minikube 1/1 Running 0 2h kube-apiserver-minikube 1/1 Running 0 2h kube-controller-manager-minikube 1/1 Running 0 2h kube-dns-86f4d74b45-rjql8 3/3 Running 0 2h kube-proxy-dv268 1/1 Running 0 2h kube-scheduler-minikube 1/1 Running 0 2h kubernetes-dashboard-5498ccf677-wktkl 1/1 Running 0 2h storage-provisioner 1/1 Running 0 2h tiller-deploy-689d79895f-bggbk 1/1 Running 0 5m

If the tiller pod’s status is Running, it can now manage Kubernetes applications from inside your cluster on behalf of Helm.

To make sure that the entire Helm application is working, search the Helm package repositiories for an application like MongoDB:

  • helm search mongodb

In the output, you will see a list of possible applications that fit your search term:

NAME CHART VERSION APP VERSION DESCRIPTION stable/mongodb 5.4.0 4.0.6 NoSQL document-oriented database that stores JSON-like do... stable/mongodb-replicaset 3.9.0 3.6 NoSQL document-oriented database that stores JSON-like do... stable/prometheus-mongodb-exporter 1.0.0 v0.6.1 A Prometheus exporter for MongoDB metrics stable/unifi 0.3.1 5.9.29 Ubiquiti Network's Unifi Controller

Now that you have installed Helm on your Kubernetes cluster, you can learn more about the package manager by creating a sample Helm chart and deploying an application from it.

Step 3 — Creating a Chart and Deploying an Application with Helm

In the Helm package manager, individual packages are called charts. Within a chart, a set of files defines an application, which can vary in complexity from a pod to a structured, full-stack app. You can download charts from the Helm repositories, or you can use the helm create command to create your own.

To test out the capabilities of Helm, create a new Helm chart named demo with the following command:

  • helm create demo

In your home directory, you will find a new directory called demo, within which you can create and edit your own chart templates.

Move into the demo directory and use ls to list its contents:

  • cd demo
  • ls

You will find the following files and directories in demo:

charts  Chart.yaml  templates  values.yaml 

Using your text editor, open up the Chart.yaml file:

  • nano Chart.yaml

Inside, you will find the following contents:

apiVersion: v1 appVersion: "1.0" description: A Helm chart for Kubernetes name: demo version: 0.1.0 

In this Chart.yaml file, you will find fields like apiVersion, which must be always v1, a description that gives additional information about what demo is, the name of the chart, and the version number, which Helm uses as a release marker. When you are done examining the file, close out of your text editor.

Next, open up the values.yaml file:

  • nano values.yaml

In this file, you will find the following contents:

# Default values for demo. # This is a YAML-formatted file. # Declare variables to be passed into your templates.  replicaCount: 1  image:   repository: nginx   tag: stable   pullPolicy: IfNotPresent  nameOverride: "" fullnameOverride: ""  service:   type: ClusterIP   port: 80  ingress:   enabled: false   annotations: {}     # nginx     # "true"   paths: []   hosts:     - chart-example.local   tls: []   #  - secretName: chart-example-tls   #    hosts:   #      - chart-example.local  resources: {}   # We usually recommend not to specify default resources and to leave this as a conscious   # choice for the user. This also increases chances charts run on environments with little   # resources, such as Minikube. If you do want to specify resources, uncomment the following   # lines, adjust them as necessary, and remove the curly braces after 'resources:'.   # limits:   #  cpu: 100m   #  memory: 128Mi   # requests:   #  cpu: 100m   #  memory: 128Mi  nodeSelector: {}  tolerations: []  affinity: {} 

By changing the contents of values.yaml, chart developers can supply default values for the application defined in the chart, controlling replica count, image base, ingress access, secret management, and more. Chart users can supply their own values for these parameters with a custom YAML file using helm install. When a user provides custom values, these values will override the values in the chart’s values.yaml file.

Close out the values.yaml file and list the contents of the templates directory with the following command:

  • ls templates

Here you will find templates for various files that can control different aspects of your chart:

deployment.yaml  _helpers.tpl  ingress.yaml  NOTES.txt  service.yaml  tests 

Now that you have explored the demo chart, you can experiment with Helm chart installation by installing demo. Return to your home directory with the following command:

  • cd

Install the demo Helm chart under the name web with helm install:

  • helm install --name web ./demo

You will get the following output:

NAME: web LAST DEPLOYED: Wed Feb 20 20:59:48 2019 NAMESPACE: default STATUS: DEPLOYED RESOURCES: ==> v1/Service NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE web-demo ClusterIP <none> 80/TCP 0s ==> v1/Deployment NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE web-demo 1 0 0 0 0s ==> v1/Pod(related) NAME READY STATUS RESTARTS AGE web-demo-5758d98fdd-x4mjs 0/1 ContainerCreating 0 0s NOTES: 1. Get the application URL by running these commands: export POD_NAME=$ (kubectl get pods --namespace default -l "," -o jsonpath="{.items[0]}") echo "Visit to use your application" kubectl port-forward $ POD_NAME 8080:80

In this output, you will find the STATUS of your application, plus a list of relevant resources in your cluster.

Next, list the deployments created by the demo Helm chart with the following command:

  • kubectl get deploy

This will yield output that will list your active deployments:


Listing your pods with the command kubectl get pods would show the pods that are running your web application, which would look like the following:

NAME READY STATUS RESTARTS AGE web-demo-5758d98fdd-nbkqd 1/1 Running 0 4m

To demonstrate how changes in the Helm chart can release different versions of your application, open up demo/values.yaml in your text editor and change replicaCount: to 3 and image:tag: from stable to latest. In the following code block, you will find what the YAML file should look like after you have finished modifying it, with the changes highlighted:

# Default values for demo. # This is a YAML-formatted file. # Declare variables to be passed into your templates.  replicaCount: 3  image:   repository: nginx   tag: latest   pullPolicy: IfNotPresent  nameOverride: "" fullnameOverride: ""  service:   type: ClusterIP   port: 80 . . . 

Save and exit the file.

Before you deploy this new version of your web application, list your Helm releases as they are now with the following command:

  • helm list

You will receive the following output, with the one deployment you created earlier:

NAME REVISION UPDATED STATUS CHART APP VERSION NAMESPACE web 1 Wed Feb 20 20:59:48 2019 DEPLOYED demo-0.1.0 1.0 default

Notice that REVISION is listed as 1, indicating that this is the first revision of the web application.

To deploy the web application with the latest changes made to demo/values.yaml, upgrade the application with the following command:

  • helm upgrade web ./demo

Now, list the Helm releases again:

  • helm list

You will receive the following output:

NAME REVISION UPDATED STATUS CHART APP VERSION NAMESPACE web 2 Wed Feb 20 21:18:12 2019 DEPLOYED demo-0.1.0 1.0 default

Notice that REVISION has changed to 2, indicating that this is the second revision.

To find the history of the Helm releases for web, use the following:

  • helm history web

This will show both of the revisions of the web application:

REVISION        UPDATED                         STATUS          CHART           DESCRIPTION 1               Wed Feb 20 20:59:48 2019        SUPERSEDED      demo-0.1.0      Install complete 2               Wed Feb 20 21:18:12 2019        DEPLOYED        demo-0.1.0      Upgrade complete 

To roll back your application to revision 1, enter the following command:

  • helm rollback web 1

This will yield the following output:

Rollback was a success! Happy Helming!

Now, bring up the Helm release history:

  • helm history web

You will receive the following list:

REVISION UPDATED STATUS CHART DESCRIPTION 1 Wed Feb 20 20:59:48 2019 SUPERSEDED demo-0.1.0 Install complete 2 Wed Feb 20 21:18:12 2019 SUPERSEDED demo-0.1.0 Upgrade complete 3 Wed Feb 20 21:28:48 2019 DEPLOYED demo-0.1.0 Rollback to 1

By rolling back the web application, you have created a third revision that has the same settings as revision 1. Remember, you can always tell which revision is active by finding the DEPLOYED item under STATUS.

To prepare for the next section, clean up your testing area by deleting your web release with the helm delete command:

  • helm delete web

Examine the Helm release history again:

  • helm history web

You will receive the following output:

REVISION UPDATED STATUS CHART DESCRIPTION 1 Wed Feb 20 20:59:48 2019 SUPERSEDED demo-0.1.0 Install complete 2 Wed Feb 20 21:18:12 2019 SUPERSEDED demo-0.1.0 Upgrade complete 3 Wed Feb 20 21:28:48 2019 DELETED demo-0.1.0 Deletion complete

The STATUS for REVISION 3 has changed to DELETED, indicating that your deployed instance of web has been deleted. However, although this does delete the release, it does not delete it from store. In order to delete the release completely, run the helm delete command with the --purge flag.

  • helm delete web --purge

In this step, you have managed application releases on Kubernetes with the Helm. If you would like to study Helm further, check out our An Introduction to Helm, the Package Manager for Kubernetes tutorial, or review the official Helm documentation.

Next, you will set up and test the pipeline automation tool Jenkins X by using the jx CLI to create a CI/CD-ready Kubernetes cluster.

Step 4 — Setting Up the Jenkins X Environment

With Jenkins X, you can create your Kubernetes cluster from the ground up with pipeline automation and CI/CD solutions built in. By installing the jx CLI tool, you will be able to efficiently manage application releases, Docker images, and Helm charts, in addition to automatically promoting your applications across environments in GitHub.

Since you will be using jx to create your cluster, you must first delete the Minikube cluster that you already have. To do this, use the following command:

  • minikube delete

This will delete the local simulated Kubernete cluster, but will not delete the default directories created when you first installed Minikube. To clean these off your machine, use the following commands:

  • rm -rf ~/.kube
  • rm -rf ~/.minikube
  • rm -rf /etc/kubernetes/*
  • rm -rf /var/lib/minikube/*

Once you have completely cleared Minikube from your machine, you can move on to installing the Jenkins X binary.

First, download the compressed jx file from the official Jenkins X GitHub repository with the curl command and uncompress it with the tar command:

  • curl -L | tar xzv

Next, move the downloaded jx file to the executable path at /usr/local/bin:

  • mv jx /usr/local/bin

Jenkins X comes with a Docker Registry that runs inside your Kubernetes cluster. Since this is an internal element, security measures such as self-signed certificates can cause trouble for the program. To fix this, set Docker to use insecure registries for the local IP range. To do this, create the file /etc/docker/daemon.json and open it in your text editor:

  • nano /etc/docker/daemon.json

Add the following contents to the file:

{   "insecure-registries" : [""] } 

Save and exit the file. For these changes to take effect, restart the Docker service with the following command:

  • systemctl restart docker

To verify that you have configured Docker with insecure registries, use the following command:

  • docker info

At the end of the output, you should see the following highlighted line:

Containers: 0 Running: 0 Paused: 0 Stopped: 0 Images: 15 Server Version: 18.06.1-ce Storage Driver: overlay2 Backing Filesystem: extfs Supports d_type: true Native Overlay Diff: true . . . Registry: Labels: Experimental: false Insecure Registries: Live Restore Enabled: false

Now that you have downloaded Jenkins X and configured the Docker registry, use the jx CLI tool to create a Minikube Kubernetes cluster with CI/CD capabilities:

  • jx create cluster minikube --cpu=5 --default-admin-password=admin --vm-driver=none --memory=13314

Here you are creating a Kubernetes cluster using Minikube, with the flag --cpu=5 to set 5 CPUs and --memory=13314 to give your cluster 13314 MBs of memory. Since Jenkins X is a robust but large program, these specifications will ensure that Jenkins X works without problems in this demonstration. Also, you are using --default-admin-password=admin to set the Jenkins X password as admin and --vm-driver=none to set up the cluster locally, as you did in Step 1.

As Jenkins X spins up your cluster, you will receive various prompts at different times throughout the process that set the parameters for your cluster and determine how it will communicate with GitHub to manage your production environments.

First, you will receive the following prompt:

? disk-size (MB) 150GB

Press ENTER to continue. Next, you will be prompted for the name you wish to use with git, the email address you wish to use with git, and your GitHub username. Enter each of these when prompted, then press ENTER.

Next, Jenkins X will prompt you to enter your GitHub API token:

To be able to create a repository on GitHub we need an API Token Please click this URL,read:user,read:org,user:email,write:repo_hook,delete_repo Then COPY the token and enter in into the form below: ? API Token:

Enter your token here, or create a new token with the appropriate permissions using the highlighted URL in the preceding code block.

Next, Jenkins X will ask:

? Do you wish to use GitHub as the pipelines Git server: (Y/n) ? Do you wish to use your_GitHub_username as the pipelines Git user for GitHub server: (Y/n)

Enter Y for both questions.

After this, Jenkins X will prompt you to answer the following:

? Select Jenkins installation type: [Use arrows to move, type to filter] >Static Master Jenkins Serverless Jenkins ? Pick workload build pack: [Use arrows to move, type to filter] > Kubernetes Workloads: Automated CI+CD with GitOps Promotion Library Workloads: CI+Release but no CD

For the prior, select Static Master Jenkins, and select Kubernetes Workloads: Automated CI+CD with GitOps Promotion for the latter. When prompted to select an organization for your environment repository, select your GitHub username.

Finally, you will receive the following output, which verifies successful installation and provides your Jenkins X admin password.

Creating GitHub webhook for your_GitHub_username/environment-horsehelix-production for url Jenkins X installation completed successfully ******************************************************** NOTE: Your admin password is: admin ******************************************************** Your Kubernetes context is now set to the namespace: jx To switch back to your original namespace use: jx namespace default For help on switching contexts see: To import existing projects into Jenkins: jx import To create a new Spring Boot microservice: jx create spring -d web -d actuator To create a new microservice from a quickstart: jx create quickstart

Next, use the jx get command to receive a list of URLs that show information about your application:

  • jx get urls

This command will yield a list similar to the following:

Name                      URL jenkins          jenkins-x-chartmuseum jenkins-x-docker-registry jenkins-x-monocular-api jenkins-x-monocular-ui nexus            

You can use the URLs to view Jenkins X data about your CI/CD environment via a UI by entering the address into your browser and entering your username and password. In this case, this will be “admin” for both.

Next, in order to ensure that the service accounts in the namespaces jx, jx-staging, and jx-production have admin privileges, modify your RBAC policies with the following commands:

  • kubectl create clusterrolebinding jx-staging1 --clusterrole=cluster-admin --user=admin --user=expose --group=system:serviceaccounts --serviceaccount=jx-staging:expose --namespace=jx-staging
  • kubectl create clusterrolebinding jx-staging2 --clusterrole=cluster-admin --user=admin --user=expose --group=system:serviceaccounts --serviceaccount=jx-staging:default --namespace=jx-staging
  • kubectl create clusterrolebinding jx-production1 --clusterrole=cluster-admin --user=admin --user=expose --group=system:serviceaccounts --serviceaccount=jx-production:expose --namespace=jx-productions
  • kubectl create clusterrolebinding jx-production2 --clusterrole=cluster-admin --user=admin --user=expose --group=system:serviceaccounts --serviceaccount=jx-production:default --namespace=jx-productions
  • kubectl create clusterrolebinding jx-binding1 --clusterrole=cluster-admin --user=admin --user=expose --group=system:serviceaccounts --serviceaccount=jx:expose --namespace=jx
  • kubectl create clusterrolebinding jx-binding2 --clusterrole=cluster-admin --user=admin --user=expose --group=system:serviceaccounts --serviceaccount=jx:default --namespace=jx

Now that you have created your local Kubernetes cluster with Jenkins X functionality built in, you can move on to creating an application on the platform to test its CI/CD capabilities and experience a Jenkins X pipeline.

Step 5 — Creating a Test Application in Your Jenkins X Environment

With your Jenkins X environment set up in your Kubernetes cluster, you now have CI/CD infrastructure in place that can help you automate a testing pipeline. In this step, you will try this out by setting up a test application in a working Jenkins X pipeline.

For demonstration purposes, this tutorial will use a sample RSVP application created by the CloudYuga team. You can find this application, along with other webinar materials, at the DO-Community GitHub repository.

First, clone the sample application from the repository with the following command:

  • git clone

Once you’ve cloned the repository, move into the rsvpapp directory and remove the git files:

  • cd rsvpapp
  • rm -r .git/

To initialize a git repository and a Jenkins X project for a new application, you can use jx create to start from scratch or a template, or jx import to import an existing application from a local project or git repository. For this tutorial, import the sample RSVP application by running the following command from within the application’s home directory:

  • jx import

Jenkins X will prompt you for your GitHub username, whether you’d like to initialize git, a commit message, your organization, and the name you would like for your repository. Answer yes to initialize git, then provide the rest of the prompts with your individual GitHub information and preferences. As Jenkins X imports the application, it will create Helm charts and a Jenkinsfile in your application’s home directory. You can modify these charts and the Jenkinsfile as per your requirements.

Since the sample RSVP application runs on port 5000 of its container, modify your charts/rsvpapp/values.yaml file to match this. Open the charts/rsvpapp/values.yaml in your text editor:

  • nano charts/rsvpapp/values.yaml

In this values.yaml file, set service:internalPort: to 5000. Once you have made this change, your file should look like the following:

# Default values for python. # This is a YAML-formatted file. # Declare variables to be passed into your templates. replicaCount: 1 image:   repository: draft   tag: dev   pullPolicy: IfNotPresent service:   name: rsvpapp   type: ClusterIP   externalPort: 80   internalPort: 5000   annotations: "true" " nginx" resources:   limits:     cpu: 100m     memory: 128Mi   requests:     cpu: 100m     memory: 128Mi ingress:   enabled: false 

Save and exit your file.

Next, change the charts/preview/requirements.yaml to fit with your application. requirements.yaml is a YAML file in which developers can declare chart dependencies, along with the location of the chart and the desired version. Since our sample application uses MongoDB for database purposes, you’ll need to modify the charts/preview/requirements.yaml file to list MongoDB as a dependency. Open the file in your text editor with the following command:

  • nano charts/preview/requirements.yaml

Edit the file by adding the mongodb-replicaset entry after the alias: cleanup entry, as is highlighted in the following code block:

# !! File must end with empty line !! dependencies: - alias: expose   name: exposecontroller   repository:   version: 2.3.92 - alias: cleanup   name: exposecontroller   repository:   version: 2.3.92 - name: mongodb-replicaset   repository:   version: 3.5.5    # !! "alias: preview" must be last entry in dependencies array !!   # !! Place custom dependencies above !! - alias: preview   name: rsvpapp   repository: file://../rsvpapp 

Here you have specified the mongodb-replicaset chart as a dependency for the preview chart.

Next, repeat this process for your rsvpapp chart. Create the charts/rsvpapp/requirements.yaml file and open it in your text editor:

  • nano charts/rsvpapp/requirements.yaml

Once the file is open, add the following, making sure that there is a single line of empty space before and after the populated lines:

 dependencies: - name: mongodb-replicaset   repository:   version: 3.5.5  

Now you have specified the mongodb-replicaset chart as a dependency for your rsvpapp chart.

Next, in order to connect the frontend of the sample RSVP application to the MongoDB backend, add a MONGODB_HOST environment variable to your deployment.yaml file in charts/rsvpapp/templates/. Open this file in your text editor:

  • nano charts/rsvpapp/templates/deployment.yaml

Add the following highlighted lines to the file, in addition to one blank line at the top of the file and two blank lines at the bottom of the file. Note that these blank lines are required for the YAML file to work:

 apiVersion: extensions/v1beta1 kind: Deployment metadata:   name: {{ template "fullname" . }}   labels:     draft: {{ default "draft-app" .Values.draft }}     chart: "{{ .Chart.Name }}-{{ .Chart.Version | replace "+" "_" }}" spec:   replicas: {{ .Values.replicaCount }}   template:     metadata:       labels:         draft: {{ default "draft-app" .Values.draft }}         app: {{ template "fullname" . }} {{- if .Values.podAnnotations }}       annotations: {{ toYaml .Values.podAnnotations | indent 8 }} {{- end }}     spec:       containers:       - name: {{ .Chart.Name }}         image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"         env:         - name: MONGODB_HOST           value: "mongodb://{{.Release.Name}}-mongodb-replicaset-0.{{.Release.Name}}-mongodb-replicaset,{{.Release.Name}}-mongodb-replicaset-1.{{.Release.Name}}-mongodb-replicaset,{{.Release.Name}}-mongodb-replicaset-2.{{.Release.Name}}-mongodb-replicaset:27017"         imagePullPolicy: {{ .Values.image.pullPolicy }}         ports:         - containerPort: {{ .Values.service.internalPort }}         resources: {{ toYaml .Values.resources | indent 12 }}   

With these changes, Helm will be able to deploy your application with MongoDB as its database.

Next, examine the Jenkinsfile generated by Jenkins X by opening the file from your application’s home directory:

  • nano Jenkinsfile

This Jenkinsfile defines the pipeline that is triggered every time you commit a version of your application to your GitHub repository. If you wanted to automate your code testing so that the tests are triggered every time the pipeline is triggered, you would add the test to this document.

To demonstrate this, add a customized test case by replacing sh "python -m unittest" under stage('CI Build and push snapshot') and stage('Build Release') in the Jenkinsfile with the following highlighted lines:

. . .   stages {     stage('CI Build and push snapshot') {       when {         branch 'PR-*'       }       environment {         PREVIEW_VERSION = "0.0.0-SNAPSHOT-$  BRANCH_NAME-$  BUILD_NUMBER"         PREVIEW_NAMESPACE = "$  APP_NAME-$  BRANCH_NAME".toLowerCase()         HELM_RELEASE = "$  PREVIEW_NAMESPACE".toLowerCase()       }       steps {         container('python') {           sh "pip install -r requirements.txt"           sh "python -m pytest tests/"           sh "export VERSION=$  PREVIEW_VERSION && skaffold build -f skaffold.yaml"           sh "jx step post build --image $  DOCKER_REGISTRY/$  ORG/$  APP_NAME:$  PREVIEW_VERSION"           dir('./charts/preview') {             sh "make preview"             sh "jx preview --app $  APP_NAME --dir ../.."           }         }       }     }     stage('Build Release') {       when {         branch 'master'       }       steps {         container('python') {            // ensure we're not on a detached head           sh "git checkout master"           sh "git config --global credential.helper store"           sh "jx step git credentials"            // so we can retrieve the version in later steps           sh "echo $  (jx-release-version) > VERSION"           sh "jx step tag --version $  (cat VERSION)"           sh "pip install -r requirements.txt"           sh "python -m pytest tests/"           sh "export VERSION=`cat VERSION` && skaffold build -f skaffold.yaml"           sh "jx step post build --image $  DOCKER_REGISTRY/$  ORG/$  APP_NAME:$  (cat VERSION)"         }       }     } . . . 

With the added lines, the Jenkins X pipeline will install dependencies and carry out a Python test whenever you commit a change to your application.

Now that you have changed the sample RSVP application, commit and push these changes to GitHub with the following commands:

  • git add *
  • git commit -m update
  • git push

When you push these changes to GitHub, you will trigger a new build of your application. If you open the Jenkins UI by navigating to and entering “admin” for your username and password, you will find information about your new build. If you click “Build History” from the menu on the left side of the page, you should see a history of your committed builds. If you click on the blue icon next to a build then select “Console Ouput” from the lefthand menu, you will find the console output for the automated steps in your pipeline. Scrolling to the end of this output, you will find the following message:

. . . Finished: SUCCESS

This means that your application has passed your customized tests and is now successfully deployed.

Once Jenkins X builds the application release, it will promote the application to the staging environment. To verify that your application is running, list the applications running on your Kubernetes cluster by using the following command:

  • jx get app

You will receive output similar to the following:


From this, you can see that Jenkins X has deployed your application in your jx-staging environment as version 0.0.2. The output also shows the URL that you can use to access your application. Visiting this URL will show you the sample RSVP application:

Sample RSVP Application in the Staging Environment

Next, check out the activity of your application with the following command:

  • jx get activity -f rsvpapp

You will receive output similar to the following:

STEP STARTED AGO DURATION STATUS your_GitHub_username/rsvpappv/master #1 3h42m23s 4m51s Succeeded Version: 0.0.1 Checkout Source 3h41m52s 6s Succeeded CI Build and push snapshot 3h41m46s NotExecuted Build Release 3h41m46s 56s Succeeded Promote to Environments 3h40m50s 3m17s Succeeded Promote: staging 3h40m29s 2m36s Succeeded PullRequest 3h40m29s 1m16s Succeeded PullRequest: Merge SHA: dc33d3747abdacd2524e8c22f0b5fbb2ac3f6fc7 Update 3h39m13s 1m20s Succeeded Status: Success at: Promoted 3h39m13s 1m20s Succeeded Application is at: Clean up 3h37m33s 1s Succeeded your_GitHub_username/rsvpappv/master #2 28m37s 5m57s Succeeded Version: 0.0.2 Checkout Source 28m18s 4s Succeeded CI Build and push snapshot 28m14s NotExecuted Build Release 28m14s 56s Succeeded Promote to Environments 27m18s 4m38s Succeeded Promote: staging 26m53s 4m0s Succeeded PullRequest 26m53s 1m4s Succeeded PullRequest: Merge SHA: 976bd5ad4172cf9fd79f0c6515f5006553ac6611 Update 25m49s 2m56s Succeeded Status: Success at: Promoted 25m49s 2m56s Succeeded Application is at: Clean up 22m40s 0s Succeeded

Here you are getting the Jenkins X activity for the RSVP application by applying a filter with -f rsvpapp.

Next, list the pods running in the jx-staging namespace with the following command:

  • kubectl get pod -n jx-staging

You will receive output similar to the following:

NAME                                 READY     STATUS    RESTARTS   AGE jx-staging-mongodb-replicaset-0      1/1       Running   0          6m jx-staging-mongodb-replicaset-1      1/1       Running   0          6m jx-staging-mongodb-replicaset-2      1/1       Running   0          5m jx-staging-rsvpapp-c864c4844-4fw5z   1/1       Running   0          6m 

This output shows that your application is running in the jx-staging namespace, along with three pods of the backend MongoDB database, adhering to the changes you made to the YAML files earlier.

Now that you have run a test application through the Jenkins X pipeline, you can try out promoting this application to the production environment.

Step 6 — Promoting your Test Application to a Different Namespace

To finish up this demonstration, you will complete the CI/CD process by promoting the sample RSVP application to your jx-production namespace.

First, use jx promote in the following command:

  • jx promote rsvpapp --version=0.0.2 --env=production

This will promote the rsvpapp application running with version=0.0.2 to the production environment. Throughout the build process, Jenkins X will prompt you to enter your GitHub account information. Answer these prompts with your individual responses as they appear.

After successful promotion, check the list of applications:

  • jx get app

You will receive output similar to the following:


With this PRODUCTION information, you can confirm that Jenkins X has promoted rsvpapp to the production environment. For further verification, visit the production URL in your browser. You should see the working application, now runnning from “production”:

Sample RSVP Application in the Production Environment

Finally, list your pods in the jx-production namespace.

  • kubectl get pod -n jx-production

You will find that rsvpapp and the MongoDB backend pods are running in this namespace:

NAME                                     READY     STATUS    RESTARTS   AGE jx-production-mongodb-replicaset-0       1/1       Running   0          1m jx-production-mongodb-replicaset-1       1/1       Running   0          1m jx-production-mongodb-replicaset-2       1/1       Running   0          55s jx-production-rsvpapp-54748d68bd-zjgv7   1/1       Running   0          1m  

This shows that you have successfully promoted the RSVP sample application to your production environment, simulating the production-ready deployment of an application at the end of a CI/CD pipeline.


In this tutorial, you used Helm to manage packages on a simulated Kubernetes cluster and customized a Helm chart to package and deploy your own application. You also set up a Jenkins X environment on your Kubernetes cluster and run a sample application through a CI/CD pipeline from start to finish.

You now have experience with these tools that you can use when building a CI/CD system on your own Kubernetes cluster. If you’d like to learn more about Helm, check out our An Introduction to Helm, the Package Manager for Kubernetes and How To Install Software on Kubernetes Clusters with the Helm Package Manager articles. To explore further CI/CD tools on Kubernetes, you can read about the Istio service mesh in the next tutorial in this webinar series.

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Easier ways to handle arrays — plus a little string manipulation

Primitive arrays in Java are not very object-oriented. You can get around this shortcoming by using a Vector, but, as I’ll explain in more detail below, this is often overkill. The first tool I will introduce is a simple object-oriented wrapper for a primitive array. After discussing arrays, I will move on to the second tool, a pair of little string manipulation routines that I use for splitting and joining, and that have come in handy for me many times.

Dealing with arrays can be a hairy business. You want to use primitive arrays for fast access and low memory overhead, but you don’t always know how big an array has to be until it’s already populated. You can use a Vector, but doing so means that each primitive value must be wrapped in an object. For example, any int has to be wrapped in an Integer object. But don’t lose heart — there is a happy medium, and that is this month’s first tool.

To read this article in full, please click here

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