Installing Jenkins on Google Cloud Platform

In this post, I explain how to correctly set up a production-ready FREE Jenkins installation on Google Cloud Platform.

Continuous Integration (CI) proved to be of extreme importance to developer productivity. Implementing a CI pipeline sets the framework for code contributors to make sure their new additions/deletions improve the code base and don’t fall back to a non-ending journey of debugging. When it comes to implementing the pipeline, there are many cloud-based tools that can make this automation easier. For example, CircleCI, Travis CI, GitLab CI and the newly-introduced (at the time of writing) GitHub Actions. However, there are some cases where a project needs to self-host its automation server, and this is where Jenkins comes as a well-developed and well-maintained automation server.

In this post, I show how to correctly set up a prodcution-level master Jenkins server. This demo is implemented on Google Cloud Platform as it offers unlimited free (forever or until further notification) Compute Engine instance. It is a small instance (F-1 micro), but should be fine for small tasks. If you have builds that take longer times, or requires a large amount of memory, you should start a bigger server on any cloud provider. Also, we will use Debian GNU/Linux 9 as the OS on whichever instance you choose.

Create Compute Engine Instance

STEP 1: Create an account at https://cloud.google.com and navigate to the Compute Engine section. It will ask you to create a project that resources will get assigned to. The screen you should start from in this tutorial is shown below.

STEP 2: Click Create and type in instance name. Choose a general purpose instance, and the size should be F-1 micro (which is the one available for free).

STEP 3: Select Debian GNU/Linux 9 (stretch).

STEP 4: Configure network access by choosing allow defaul access. Also, make sure to allow HTTP and HTTPS traffic.

STEP 5: Click Create

STEP 6: Once the VM is created, ssh to the machine from the browser by selecting from the menu open in a browser window.

STEP 7: You are in!

Set up Jenkins

In this part, we want to install jenkins and serve it at a given URL. We will also create an HTTPS certificate using let’s encrypt.

Install Prerequisites

  1. sudo apt update: updates packages
  2. sudo apt install openjdk-8-jdk: install Java 8 (a prerequisite for Jenkins)
  3. sudo apt install apache2: install Apache web server (to serve Jenkins traffic)
  4. sudo apt install build-essential: install build tools for some apache modules to work.
  5. sudo a2enmod proxy && sudo a2enmod proxy_http && sudo a2enmod proxy_balancer && sudo a2enmod lbmethod_byrequests sudo a2enmod headers: enable Apache modules for proxying.
  6. sudo systemctl restart apache2: restart Apache to enable changes in the modules

CHECK: Apache should now be installed and working properly. Go to the IP address of the instance in the web browser. You should see the default landing page of Apache. If not, something has gone wrong. Check Apache log files. Also, if you type in the terminal sudo service apache2 status, you should see active (running)

Install Jenkins

Refer to Jenkins documentation if you are using a different OS.

  1. wget -q -O - https://pkg.jenkins.io/debian/jenkins.io.key | sudo apt-key add -
  2. sudo sh -c 'echo deb http://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'
  3. sudo apt update
  4. sudo apt install jenkins
  5. sudo systemctl start jenkins

CHECK: Jenkins is now installed. Check that it is running properly by typing in sudo service jenkins status. You should see active (running). If not, check the logs.

  1. cd /etc/apache2/sites-available/
  2. vim sudo vim 000-default.conf
  3. Configure the VirtualHost to look as the following. Replace the domain name with the domain you plan to link. In my case, it is jenkins.abdelrahmanhosny.me. Also, edit ServerAdmin email.

     <VirtualHost *:80>
             ServerName jenkins.abdelrahmanhosny.me
    
             ProxyPreserveHost On
             ProxyPass / http://localhost:8080/ nocanon
             ProxyPassReverse / http://localhost:8080/
             RequestHeader set "X-Forwarded-Proto" expr=%{REQUEST_SCHEME}
             ProxyRequests Off
             AllowEncodedSlashes NoDecode
    
             ServerAdmin email@domain
             DocumentRoot /var/www/html/jenkins
    
             ErrorLog ${APACHE_LOG_DIR}/error-jenkins.log
             CustomLog ${APACHE_LOG_DIR}/access-jenkins.log combined
     </VirtualHost>
    
  4. sudo systemctl restart apache2
  5. IMPORTANT: Go to your domain registrar and update the A record of the domain to point to the IP address of your instance. Allow for some time for the DNS recrods to propagate (usually about 10 minutes).

CHECK: In a new browser tab, type in the domain name, it should open the defaul Jenkins page. Do NOT configure Jenkins yet. If the page is not loading, the DNS record might be unset yet. If you waited for more time, try checking host <domain name> in your local terminal. If it shows the IP address of the machine, then some other error in the server happened. Check the Apache log.

Obtain HTTPS Certificate

  1. sudo add-apt-repository ppa:certbot/certbot
  2. vim /etc/apt/sources.list and add the following lines.

     deb http://deb.debian.org/debian/ stretch main
     deb-src http://deb.debian.org/debian/ stretch main
     deb http://security.debian.org/ stretch/updates main
     deb-src http://security.debian.org/ stretch/updates main
     deb http://deb.debian.org/debian/ stretch-updates main
     deb-src http://deb.debian.org/debian/ stretch-updates main
     deb http://ftp.debian.org/debian stretch-backports main
    
  3. sudo apt update
  4. sudo apt install python-certbot-apache -t stretch-backports
  5. sudo certbot --apache -d jenkins.abdelrahmanhosny.me and replace the domain with your domain name.

CHECK: If you go to your web browser page for your domain and refresh it, you should see it being served under HTTPS now.

Configure Jenkins

  1. Obtain the initial password: sudo cat /var/lib/jenkins/secrets/initialAdminPassword in the terminal.
  2. Use the password to start the configuration wizard in the browser. Use the default settings for the setup, unless you know what you are looking for.

Congratulations! You have a production-ready Jenkins master node.

Install Blue Ocean

Jenkins is mainly a very powerful automation server. However, when it was started, it wasn’t very CI friendly. However, thanks to its plugin ecosystem, great plugins made common tasks easy. The most important one is Blue Ocean plugin. It makes defining a CI pipeline from a git repository a simple task.

  1. In Jenkins dashboard, choose Manage Jenkins from the left sidebar.
  2. Click Manage Plugins.
  3. Select Available tab.
  4. Search for blue ocean from the search box in the top right.
  5. Select Blue Ocean and click Download now and install after restart.
  1. In the dashboard, click Open Blue Ocean from the left sidebar.
  2. Choose GitHub from the available integration options.
  3. Since you don’t have an access key, click the link below the box to obtain an access key from GitHub with the permissions that Jenkins need.
  4. Save this key locally in a safe place. We will use it again shortly.

Build a Pipeline

Select your repository and create a pipeline. If your repository doesn’t have a Jenkinsfile already, the wizard will offer you to create one using its nice step-by-step guide.

Trigger on Git Pushes

If you push code to your repository, the pipeline won’t start automatically. The reason is Jenkins couldn’t create a webhook on GitHub to be notified if new changes are pushed to the repo. In order to fix this, follow the following steps

  1. In Jenkins dashboard, choose Manage Jenkins from the left sidebar.
  2. Click Configure System.
  3. Under GitHub Section, click Add
  4. From the kind menu, select Secret text
  5. Paste in the GitHub access key (that we saved previously) in the Secret field.
  6. Select Manage hooks and then click Test connection.
  7. If connection is successful, save the settings.
  8. Now, newly created pipelines from the Blue Ocean interface will automatlically add a web hook to your GitHub repo. However, you might need to re-create the pipeline for the repo you added before in order to create a web hook.

Git Submodules

If your repository uses Git submodules, an additional configuration step needs to be done after the pipeline of the repository is added through Blue Ocean interface.

  1. Go back to main Jenkins dashboard, and click on the project.
  2. Select Configure from the left sidebar.
  3. Under Branch Sources, click on Add
  4. Select Advanced sub-modules behaviours
  5. Select Recursively update submodules and Use credentials from default remote of parent repository.
  6. Click save and re-run the pipeline.

Summary

In this short tutorial, we created a production-ready Jenkins master node on a free GCP instance. It works well for small CI pipelines. Following the same steps on a bigger VM instance makes the Jenkins server capable of handling serious tasks in modern CI pipelines.


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