Levvel Blog - CI/CD—Going Stateless with Pivotal Cloud Foundry

CI/CD—Going Stateless with Pivotal Cloud Foundry

By now, most of us are no strangers to the CI/CD methodology and how it enables teams to continuously test and release new code to customers in “real time” without any disruption of services.

Living in the age of Platform as a Service (PaaS) infrastructures, such as Pivotal Cloud Foundry (PCF), has enabled software organizations to adopt a more automated, streamlined and even stateless approach to CI/CD. In this blog, we’ll take a look at what CI/CD looks like within the PCF ecosystem.

Stateless PaaS Pipelines

PCF offers developers and operators a consistent approach to deploy applications in a dependable and repetitious manner via its marketplace services, buildpacks, and underlining infrastructure. This simplifies the CD process, but what about CI?

ConcourseCI is the prefered CI engine for PCF. It uses a declarative API-based model to set and manage pipelines in a stateless manner, enabling developers and operators to focus on what matters most—successful deployments. Pipelines are made up of jobs that consists of one or more tasks. The jobs and tasks are run as containers within the ConcourseCI infrastructure. Each task’s results and artifacts are passed as conditions or triggers to the next job or task in the pipeline, and this process continues until the final artifact is deployed.

Pipelines are much like they sound—they are a sequence of jobs that can be triggered when a developer commits code to a specified repository. Pipelines can be built to compile code, apply smoke tests, deploy an artifact to staging and eventually to production.

What’s Gained and Lost?

ConcourseCI considers container images, code repositories, and storage (on-premise or cloud-provided) for what they are—resources. These resources are defined in the pipeline’s YAML file. The pipeline’s tasks uses these resources to compile code and create intermediate artifacts without leaving a local fingerprint. Other CI engines, such as Jenkins, by default store and pass artifacts locally between tasks unless tweaked to do so otherwise. The ConcourseCI’s model enables pipelines to consume resources, such as storage and repositories, by mounting them to a container so that they can be used until the tasks are completed. ConcourseCI destroys these containers once all the tasks are completed, creating a stateless process promoting better Disaster Recovery (DR) and business continuity.

Hands-On: Blue-Green Deployments

Let us start by creating a simple blue-green deployment using ConcourseCI and PCF. For context, let us dig a little deeper into the concept of pipelines, jobs, tasks, and resources and review some of the common tools used by developers.

Tools

  • Fly CLI
    Fly CLI is the command line interface developers use to create pipelines, tasks and jobs in ConcouseCI. The steps to install Fly CLI are provided through the ConcourseCI dashboard.

  • A Hello World application
    A simple Java / Spring Boot Hello World application—create a fork and clone the repository.

    – Navigate to the GitHub repository for the Hello World Application by clicking here, fork the GitHub repository by clicking on the Fork button in the top-right corner of the page

Fork button

  • You can clone your forked repository by executing the following command. Replace the “<...>” with your GitHub ID. If you do not have the Git client installed, follow the steps outlined here. (Alter the paths and commands if you are using Windows).
~$ mkdir ~/pcfdev

~$ cd ~/pcfdev

~$ git clone [git@github.com](mailto:git@github.com):<...>/spring-hello-world.git
  • pipeline.yml and credentials.yml – The pipeline.yml file is used to define the ConcourseCI pipeline resources, jobs and tasks – The credentials.yml is used by the Fly CLI command line interface to connect to the PCFDev instance

  • ConcourseCI instance VirtualBox and Vagrant are used to run a ConcourseCI instance, follow the link below to install them. – VirtualBoxVagrantConcourseCI (select the New tab, under “How to use this box with Vagrant”)

  • PCFDev instance
    PCFDev is used to locally emulate a production PCF environment. Follow the link below to install PCFDev. – PCFDev

Resources

Resources are docker-images, source code repositories, or storage blobs used by the ConcourseCI pipeline. The pipeline uses a YAML file to define all the resources.

Locate the pipeline.yml in the forked Git repository, it is in the spring-hello-world/ci/ directory. You must replace the placeholder with your Git ID, so the resource points to your forked copy of the Hello World application’s Git repository.

resources:  
- name: spring-hello-world  
  type: git  
  source:  
    branch: master  
    uri: [https://github.com](https://github.com)<replace your id here>/spring-hello-world.git

Jobs

As previously described, pipelines are made up of jobs and tasks. We will setup the pipeline so it is triggered when developers commit code changes to the Hello World application.

Find the section of the pipeline.yml file in your cloned repository and locate the following lines. This section refers to the “spring-hello-world” resource we previously defined and the “trigger: true” stanza ensures that this job is triggered when developers commit code changes to the Git repository. You can read more about the other options used here.

jobs:  
- name: maven-build-and-deploy  
  serial: true  
  public: true  
  plan:  
  - get: spring-hello-world  
    trigger: true

Tasks

A ConcourseCI job can be made up of one or more tasks. Tasks operate within containers, executing scripts or a suite of tests. Once a task is completed, it is assigned a pass or fail status. This status can be used to alter the flow of the pipeline.

Find the section of the pipeline.yml file in your cloned repository and locate the following lines. The task outlined below is used to build the Hello World application. Some interesting points to note:

  • Maven is used to build the Hello World application
  • A Ubuntu docker-image to execute the build

You can read more about the other options used here.

task: maven-build  
    config:  
      platform: linux  
      image_resource:  
        type: docker-image  
        source:  
          repository: ubuntu  
          tag: "xenial"  
      inputs:   
      - name: spring-hello-world  
      outputs:  
      - name: builds  

      run:  
        path: spring-hello-world/ci/tasks/maven-build

Push the Blue Version of the Hello World Application to PCFDev

We will create two instances of the Hello World Application in PCFDev, a blue instance and a green instance. Let us get started with the blue instance.

Open a command prompt / terminal, and from “spring-hello-world” directory execute the following command (alter the paths and commands if you are using Windows).

~$ cd ~/pcfdev/spring-hello-world

~$ cf push hellospring-blue --hostname hellospring-prod

Blue instance in PCFDev

Using the Pipeline to Push the Artifact to PCFDev

Open a command prompt / terminal and execute the following commands (alter the paths and commands if you are using Windows).

~$ cd ~/pcfdev/spring-hello-world

~$ fly -t hellospring login --concourse-url http://192.168.100.4:8080

~$ fly -t hellospring set-pipeline -c pipeline.yml -p blue-green -l credentials.yml

~$ fly -t hellospring unpause-pipeline -p blue-green
  • Use the Fly CLI command line to log in to the ConcourseCI instance. The URL is provided when you start the ConcourseCI Vagrant image. It is usually http://192.168.100.4:8080.
  • Use the Fly CLI command line to create a pipeline in ConcourseCI using the pipeline.yml file, and the credentials.yml is used by the ConcourseCI based pipeline to deploy artifacts to the PCFDev instance. The ConcourseCI / Fly CLI command reference is here.
  • By default, the pipeline is not active. The last “un-pause” command ensures that the pipeline is triggered when developers’ commit code updates Git repository.

Log in to the ConcourseCI Dashboard

Start a browser and navigate to the ConcourseCI dashboard by using the URL defined above. It is usually http://192.168.100.4:8080. Once logged in, you can navigate the dashboard to view the pipeline that was created above.

ConcourseCI Dashboard with the Blue-Green Pipeline

Edit the Hello World Application to Create the Green Version

Now let us create the green instance of the Hello World Application by triggering the blue-green pipeline.

  • Edit the Hello World Application’s index.html file, and this will trigger the blue-green pipeline’s jobs and tasks.
  • Open a command prompt / terminal and execute the following commands.
~$ cd ~/pcfdev/spring-hello-world/hellospring/application/src/main/resources/static/

~$ vi index.html
  • Make the following changes to the index.html file.
   <!-- 1.)   Edit section from Blue -->

         <h1>Spring - Blue to Prod!</h1>

   <!-- 2.)   To Green -->

         <h1>Spring - Green to Prod!</h1>

   <!-- 3.)   Close and save index.html -->
  • Execute the following commands to push your changes to the GitHub repository.
~$ git add index.html

~$ git commit -m “changing syntax from blue to green”

~$ git push origin master
  • Navigate to the ConcourseCI dashboard, click on the blue-green pipeline, and click on the maven-build-and-deploy job to check on the progress of the pipeline.

Maven Build of New Code

  • Following the success of our maven build, another task will deploy the Hello World Application to the green instance with our changes to the index.html file.

  • Once the maven build-deploy and unit-test jobs have passed, we will see the route is updated and is now pointing at the green instance in our PCFDev environment.

Green Instance Now in Production

  • Navigate to the http://hellospring-prod.local.pcfdev.io URL in your browser to see the output of the updated index.html file being rendered by the green instance of the Hello World Application.

Successful Pipeline Deployment Overview

  • Navigate back to the ConcourseCI dashboard to view the current status of the blue-green pipeline.

In Conclusion

As applications and infrastructure evolve, CI/CD pipelines need to as well in order to keep up with the frantic pace in which organizations strive to deliver new features to its customers. In a stateless and declarative model, we accomplish this by removing the need for third party plug-ins, CI engine backups, and operator overhead. Simply “Keep Calm and Deploy to Prod.”

Marshall Ashley

Marshall Ashley

Consultant

Solving complex problems in a crazy Open Source meets Enterprise world.

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