How to setup Let’s Encrypt (SSL) Certificate on OpenShift

In previous posts I have described how to deploy a Node.js application to OpenShift. Now its time to add a custom alias to our Node.js application so that it is accessible through a custom domain, like Currently it is accessible only through Off course we also want valid SSL certificates for our custom domain For that we need to get a certificate (a type of file) from a Certificate Authority (CA). Let’s Encrypt is a free, automated, and open certificate authority brought to you by the non-profit Internet Security Research Group (ISRG). So obviously we will use that.

Create alias via OpenShift web console
From the Applications section choose your application (e.g. testnode) and then click on change alias. For Domain Name enter your custom domain. Mine is Leave the rest of the fields blank and click Save.

To successfully use this alias, you must have an active CNAME record with your DNS provider. The alias is and the destination app is

My provider is So I went ahead, logged in and under Subdomains -> New Sub Domain I have created a new subdomain Then under DNS Configuration for, I was able to set the CNAME record to for * ( included).

And thats it!

Create certificates
We will need a valid certificate and its corresponding private key to upload to OpenShift for the new domain Under Mac OS X I have used certbot. So go ahead and install certbot:

Once installed run:

OK, that didn’t work. Obviously Let’s Encrypt wants us to prove that we are the truthful owners of The way it verifies ownership is trying to load the above URL ( and compare the received result with the expected result.

We need to modify our Node.js application to return the hash Let’s Encrypt requires when the above URL is GET. In my router.js I have added the below code snippet:

The above code reads the hash from the requested URL and returns it. OK, lets try it one more time.

Hmmmm, that didn’t work either. At this point I should probably read the manual. But apparently when the URL is requested, it expects xxxxxxxxxxx.yyyyyyyyyyy as a result. So I went and modified my router.js again:

Giving it a try again, I finally got my certificates:

The generated certificate and private key is located under /etc/letsencrypt/archive/test.testnode.comc/cert1.pem and /etc/letsencrypt/archive/ respectively.

Upload certificates to OpenShift
For this we will use the OpenShift client tools:

Thats it! Our application is now accessible through


Adding version number in Node.js app using Jenkins/OpenShift deploy

In a previous post I have illustrated how to deploy a Node.js app to OpenShift from a private GitHub repository using Jenkins.

It is often the case that you want to display the revision of the current code deployed in your test environment so you can quickly see if the running version of your app uses the latest code base. In my opinion this is a task for your build tool (such as Ant, Maven, Gradle, etc) or your automation server such as Jenkins.

I want to keep the following information in a file called version.txt and serve it when a user tries to GET it. Since I am using express, all I have to do in order to serve static files is the following:

Now, all I have to do is tell Jenkins to create the file version.txt, fill it with the necessary information and save it under public in my app’s deployment directory on the OpenShift server. You can find out the OpenShift deployment directory using the predefined environment variable $OPENSHIFT_REPO_DIR:

As we saw in OpenShift’s Jenkins configuration, a shell command is executed that deploys our Node.js application. So go ahead and navigate to YOUR_PROJECT_NAME -> Configuration. Scroll down where it says Execute Shell. This field already contains a bunch of shell commands. Append the following:

And thats it! The next time Jenkins builds your project, it will execute the above shell command which will in turn create a version.txt file and place it under public in you Node.js app. You can then access it via


Deploy a Node.js app to OpenShift from a private GitHub repository

Assuming you have an OpenShift account go ahead and login. Otherwise create an account first.

Next, login to OpenShift’s web console, create a new Node.js application by clicking on Add Application… and then selecting Node.js 0.10.

Fill out the fields such as Public URL (e.g. testnode) and leave the rest with their default value and click on Create Application.

Once your application is created you will receive a repository URL to a newly created Git repository hosted on OpenShift similar to:

Install the OpenShift client tools:

Once installed, run the rhc setup command to configure the client tools. The setup wizard generates a new pair of SSH keys in the default .ssh folder of your home directory. The setup requires your OpenShift username and password.

Next clone your GitHub repository:

Add a new remote called openshift and merge your Github repository into your Openshift repository:

The git push openshift HEAD starts a new Jenkins build and deploys your Node.js application. Once it is done, you can access your Node.js application at

You can also go ahead and clone your OpenShift repository if you want to:

This includes an .openshift directory which contains various OpenShift metadata and configuration that are important for deployment.

(Optional) Setting up environment variables
It is often the case that your web application requires some sort of configuration for certain functionalities such as an email contact form. This configuration may include parameters such as username and password for the mail server. This configuration is usually done using a sensitive.config.js file which you include in your Node.js application using:

Since you want to avoid hardcoding usernames and passwords in source code files you can parse these to your application though environment variables. So at the end of the day your sensitive.config.js configuration file may look as follows:

and your repository stays clean from sensitive information. The process.env property returns an object containing the user environment. process.env is followed by the name of the variable you wish to access such as MAIL_USERNAME and MAIL_PASSWORD in our case. See more under process.env documentation.

Now, we need to setup these environment variables in OpenShift. So go ahead, fire up your Terminal and enter:

What is left to do is restart you Node.js application through the OpenShift web console.

(Optional) Skip OpenShift Git repository
You can also configure OpenShift to use only your GitHub repository for deployment by enabling Jenkins. In you web console select your Node.js application and click on Enable Jenkins. This will provide you with a Jenkins URL (e.g. along with a username and password. Open up you Jenkins URL and login using the provided username and password.

Taking a look at the build project’s configuration you can see that OpenShift already filled in the shell command to be executed on build:

If your repository is a private repository OpenShift will not be able to download the source code as it will not have the credentials to authenticate itself against the git repository.

To configure Jenkins to use GitHub we need to install some plugins. First, download the following Jenkins plugins:

In Jenkins, go to Manage Jenkins then Manage Plugins and then Advanced. Then under Upload Plugin click Choose File and upload the .hpi file to install the plugin. Do this for all the plugins in the given order:
1. github-api
2. plain-credentials
3. token-macro
4. structs
5. workflow-step-api
6. workflow-scm-step
7. scm-api
8. credentials
9. git-client
10. github
11. git

Next, go to Jenkins -> Credentials -> System -> Global credentials and click Add Credentials. Choose Kind: Username with password and Scope: Global. Enter your GitHub credentials and click OK to save.

Next, go to Jenkins -> Credentials and click on Add Domain. Enter and click OK to save.

Next, go to Jenkins -> Credentials -> System -> and click Add Credentials. Then open GitHub in a new tab and generate a new Personal Access Token. Select the scopes repo and admin:repo_hook and click Generate token.

Back in Jenkins, select Kind: Secret text and paste your access token in the Secret field. Give your credentials a Description (e.g. GitHub access token) and hit OK to save.

Then go to Manage Jenkins -> Configure System and in the GitHub section and a new GitHub server and make sure the API URL is set to Select GitHub access token in the Credentials drop down and click Test connection. Everything should work ok. Click Save.

We want GitHub to notify your Jenkins instance whenever you push commits to the repo. We’ll use Webhooks for this. Go to your GitHub repository settings (e.g. and click on Webhooks. Then click Add webhook. Under Payload URL enter and choose the Content type application/x-www-form-urlencoded. Finally, click Add webhook.

Back to Jenkins, navigate to your Jenkins build project’s configuration page. Find the checkbox GitHub project and check it. For Project url enter your GitHub repository URL (e.g.

In the Source Code Management choose Git and again enter your GitHub repository URL (e.g. For Branches to build set it to */master. For Credentials choose the username/password credentials you made earlier from the dropdown.

Scroll down to the Build Triggers section and check Build when a change is pushed to GitHub and click Save to save the changes.

Now when you push to your GitHub repository Jenkins will be notified via the Webhook and will start a new build. It will use the GitHub repository URL you specified under Source Code Management.

Thats it! Happy continuous delivery!

The Node.js application used in this tutorial is live at


Keep gh-pages in sync with master

GitHub Pages is designed to host your personal, organization, or project pages directly from a GitHub repository.

Add changes to your master branch

Add changes to gh-pages

Your page will be available at


Install Jupyter Notebook – Mac OS X

Upgrade to Python 3.x

Download and install Python 3.x. For this tutorial I have used 3.5.

Once you downloaded and run the installation app, Python 3 will be installed under:


The installer also adds the path for the above to your default path in .bash_profile so that when you type:


on the command line, the system can find it. You'll know you've been successful if you see the Python interpreter launch.

Install pip

Fire up your Terminal and type:

sudo easy_install pip

Install PySpark on Mac

  1. Go to the Spark downloads page and choose a Spark release. For this tutorial I chose spark-2.0.1-bin-hadoop2.7.
  2. Choose a package type. For this tutorial I have choses Pre-built for Hadoop 2.7 and later.
  3. Choose a download type: (Direct Download)
  4. Download Spark: spark-2.0.1-bin-hadoop2.7.tgz
  5. Unzip the folder in your home directory using the following command. tar -zxvf spark-2.0.1-bin-hadoop2.7.tgz. I prefer create an opt directory in my home directory and then unzip it under ~/opt/.

Next, we will edit our .bash_profile so we can open a spark notebook in any directory. So fire up your Terminal and type in:

nano .bash_profile

my .bash_profile looks as follows:

export SPARK_PATH=~/opt/spark-2.0.1-bin-hadoop2.7/bin
export PYSPARK_PYTHON="python3"
export PYSPARK_DRIVER_PYTHON="jupyter" 
alias snotebook='$SPARK_PATH/pyspark --master local[2]'

export GRADLE_HOME="/Users/lucas/opt/gradle-2.2.1"
export PATH="$PATH:$GRADLE_HOME/bin"

export ANT_HOME="/Users/lucas/opt/apache-ant-1.9.4"
export PATH="$PATH:$ANT_HOME/bin"

export M2_HOME="/Users/lucas/opt/apache-maven-3.2.5"
export PATH="$PATH:$M2_HOME/bin"
export PATH="/usr/local/mysql/bin:$PATH"

export MONGODB_HOME="/Users/lucas/opt/mongodb-osx-x86_64-3.0.4"

export JASYPT_HOME="/Users/lucas/opt/jasypt-1.9.2"
export PATH="$PATH:$JASYPT_HOME/bin"

export JAVA_HOME="/Library/Java/JavaVirtualMachines/jdk-9.jdk/Contents/Home"

export PATH="/opt/local/bin:/opt/local/sbin:$PATH"

# Setting PATH for Python 3.5

export PATH

The relevant stuff is:

export SPARK_PATH=~/opt/spark-2.0.1-bin-hadoop2.7/bin
export PYSPARK_PYTHON="python3"
export PYSPARK_DRIVER_PYTHON="jupyter" 
alias snotebook='$SPARK_PATH/pyspark --master local[2]'

The PYSPARK_DRIVER_PYTHON parameter and the PYSPARK_DRIVER_PYTHON_OPTS parameter are used to launch the PySpark shell in Jupyter Notebook. The --master parameter is used for setting the master node address. Here we launch Spark locally on 2 cores for local testing.

Install Jupyter Notebook with pip

First, ensure that you have the latest pip; older versions may have trouble with some dependencies:

pip3 install --upgrade pip

Then install the Jupyter Notebook using:

pip3 install jupyter

Thats it!

You can now run:


in the command line. A browser window should open with Jupyter Notebook running under http://localhost:8888/

Configure Jupyter Notebook to show line numbers


jupyter --config-dir

to get the Jupyter config directory. Mine is located under /Users/lucas/.jupyter. Run:

cd /Users/lucas/.jupyter


mkdir custom

to create a custom directory (if does not already exist). Run:

cd custom


nano custom.js

and add:

    function(IPython, events) {
            function () {
                IPython.Cell.options_default.cm_config.lineNumbers = true;

You could add any javascript. It will be executed by the ipython notebook at load time.

Install a Java 9 Kernel

Install Java 9. Java home is then:


Install kulla.jar. I have installed it under ~/opt/.

Download the kernel. Again, I placed the entire javakernel directory under ~/opt/.

This kernel expects two environment variables defined, which can be set in the kernel.json (described below):

KULLA_HOME - The full path of kulla.jar
JAVA_9_HOME - like JAVA_HOME but pointing to a java 9 environment

So go ahead and edit kernel.json in the kernel you have just download to look as follows:

 "argv": ["python3", "/Users/lucas/opt/javakernel",
          "-f", "{connection_file}"],
 "display_name": "Java 9",
 "language": "java",
 "env" : {
     "JAVA_9_HOME": "/Library/Java/JavaVirtualMachines/jdk-9.jdk/Contents/Home",
     "KULLA_HOME": "/Users/lucas/opt/kulla.jar"


cd /usr/local/share/jupyter/kernels/


mkdir java


cp /Users/lucas/opt/javakernel/kernel.json java/

to copy the edited kernel.json into the newly created java directory.

Install gnureadline by running:

pip install gnureadline

in the commoand line.

If all worked you should be able to run the kernel:

jupyter console --kernel java

and see the following output:

java version "9-ea"
Java(TM) SE Runtime Environment (build 9-ea+143)
Java HotSpot(TM) 64-Bit Server VM (build 9-ea+143, mixed mode)
Jupyter console 5.0.0

Configure Maven 3.2 to use JDK v1.7 under Mac OS X 10.9

In this article i describe how to configure Maven 3.2 to use JDK v1.7 under Mac OS X 10.9
Step 1: Download Maven
Go ahead and download the latest Maven version here. For this tutorial just download the binaries: apache-maven-3.2.1-bin.tar.gz.

Step 2: Install Maven
Once you have downloaded the zipped file extract it. There should be a folder called apache-maven-version (apache-maven-3.2.1 in my case) with contents looking something like this:
- apache-maven-3.2.1
--- bin
--- boot
--- conf
--- lib
--- README.txt

We will install Maven in ‘/usr/local/apache-maven’ So go ahead and navigate to your /usr/local/ directory. You can do this by either using the Terminal using

or just typing ‘command-shift-g’ in the Finder and then entering ‘/usr/local/’ in the input field.

Next create a new directory called ‘apache-maven’ in your /usr/local/ directory and move the
‘apache-maven-version’ folder into the newly created ‘apache-maven’ directory. So you will have
a directory structure like follows: /usr/local/apache-maven/apache-maven-3.2.1/

Open a new Terminal window and type in:

enter your password and edit your profile file to contain the following:

Hit ‘control-o’ and then enter to save and finally ‘control-x’ to exit the editor.

Step 3: Install Java v1.7
Go to the official Oracle website and download the latest version of Java SE Kit here.

Mount the .dmg file and double click the Install Package to install the latest version of Java(version 1.7.0_60 in my case).

Java will be installed under ‘/Library/Java/JavaVirtualMachines/jdk1.7.0_60.jdk/Contents/Home’ in Mac OS X 10.9 (Mavericks). You can find this out by typing

in your Terminal.

Step 4: Configure profile file
Finally we need to set the Java home directory. Again type in the following in the Terminal:

authenticate and then enter the following:

So our final .bash_profile file looks like so:

Again hit ‘control-o’ and then enter to save and finally ‘control-x’ to exit the editor.

Step 5: Verify that everything went smoothly

to verify that Maven is correctly installed. You should see something like:

Similarly run

to verify that Java is correctly installed. You should see something like:

Thats it! Thanks