DevOps/GitOps workflow:
This is a simple 3 microservices static website – a random text generator, deployed on Amazon Web Services (AWS) infrastructure:
The components are:
- Generator -> a Python program which generates random text and inserts it into a database - https://github.com/zefirnikolov/awsapp-genpart
- MariaDB -> database which stores the information from the Generator - https://github.com/zefirnikolov/awsapp-dbpart
- Web part –> an HTML/CSS frontend and Python Flask backend – the backend gets the randomly generated texts from the MariaDB database and expose them to the frontend. - https://github.com/zefirnikolov/awsapp-webpart
- Kubernetes Cluster -> This repository
The website dynamically changes, because new and new text is added.
The website is production standard deployed on an AWS, Kubernetes (K8s) cluster.
This repository represents the .yaml files that run in the cluster. For successful deployment Jenkins is used as CI and ArgoCD as CD (Jenkins is installed in the bootstrap instance, ArgoCD is deployed in the cluster). GitHub is used as a source for Development and Docker Hub for source for Deployment. Also as ArgoCD is constantly seeking for changes in the cluster and applying them – this GitHub repository becomes the Single Source of Truth for the cluster.
Jenkins Pipeline 1 (which is based on the Generator, MariaDB, Web Part Repos):
A Jenkins pipeline with a webhook is created, which catches if any change is made from the Development part to the GitHub repository responsible for it (generator github repo, db github repo or web github repo) –> the webhook activates -> It builds a new Docker Container Image with the changes in the Development part from a Dockerfile -> It sends the Image with UPDATED TAG (The env. Number of the job build) to Docker Hub. Every time the Development code is changed, a new docker container image will be created and uploaded with the UPDATED TAG.
One of the Jenkinsfiles with the job in the generator, db or web github repos:
After successful upload to Docker Hub, the Job Triggers a second Jenkins JOB
Jenkins Pipeline 2 (which is based on this GitHub Repo) This Pipeline Job is triggered from the web, generator, or db 1st Pipeline -> It UPDATES the generator.yaml, db.yaml or web.yaml file respectively (depending on which Development part a change is made) -> it changes the number of the docker hub TAG which the .yaml file pulls from Docker Hub. Now here comes the CD part – as ArgoCD constantly seeking for changes, because this .yaml files are changed – ArgoCD uploads the new .yaml files to the K8s cluster:
There is 2 Pipelines created for every microservice – 2 Pipelines for the Generator, 2 for the DB, 2 for the web app, making them 6 pipelines in total:
The repositories are separated intentionally:
- The development repositories (generator, db and web) are intended for the development team, the code of the app is managed by the developers, the GitOps is managed by the DevOps.
- The K8s cluster repository combines all the microservices in 1 cluster + adds more -> the ArgoCD itself, an Ingress Controller , SSL Certification . It exposes the whole app to the internet and makes it available and secure. This repository is managed only by the DevOps, because it commands the whole cluster.