This Udacity course capstone project operationalize a simple Python/Flask app which will return the status and the version of it in json format. It demonstrates the blue-green deployment and uses CircleCI to build and deploy the app into AWS EKS (Amazon Elastic Kubernetes Service)
This project has workflow defined in CircleCI to
- Lint and build the app image after code commit
- Push image into DockerHub
- Promote to production if app passes smoke test. Uses blue-green deployment strategy to promote app into production
The jobs and tasks pipeline defined in CircleCI can be visualized in the following picture
The blue-green deployment is described in the following picture
Since the project is going to demonstrate the blue-green deployment strategy, an initial blue environment must be setup
To setup the initial blue environment
- Install eksctl, kubectl and aws-iam-authenticator
- Execute 'bin/create_cluster.sh' to create Kubernetes cluster in AWS EKS
- Execute 'bin/setup_first_k8s_app.sh' to setup the blue environment (blue app and blue load balancer)
To use CircleCI as a CI/CD platform, this project must be followed in CircleCI and setup the following environment variables
- AWS_ACCESS_KEY_ID
- AWS_DEFAULT_REGION
- AWS_SECRET_ACCESS_KEY
- DOCKER_LOGIN
- DOCKER_PASSWORD
- KUBECONFIG_DATA
- Perform application development and code change
- Modify the CURRENT, LAST variables in config.txt in root directory of the app. CURRENT represents the version going to be released, LAST represents the previous version of the app with respect to this release (ie CURRENT)
- Commit the code change and push to github
- Makefile: contains commands to prepare the virtual environment, install dependencies and lint the build files
- app.py: the simple Flask app
- Dockerfile: contains instructions on how to containerize the microservice
- requirements.txt: dependencies for app.py
- config.txt: contains setup variables for the app
- bin/build_docker.sh: build the image of CURRENT version of the app
- bin/build_push_first_docker.sh: build and push the blue app into DockerHub
- bin/create_cluster.sh: create the EKS k8s cluster
- bin/del_current_app.sh: delete the CURRENT version of app in k8s cluster (GREEN candidate)
- bin/del_green_lb.sh: delete the green load balancer
- bin/del_last_app.sh: delete the LAST version of app in k8s cluster
- bin/deploy_green_app.sh: deploy the CURRENT version of app in k8s cluster (GREEN candidate)
- bin/deploy_green_lb.sh: deploy the green load balancer
- bin/get_k8s.sh: get the base64 string of the k8s cluster configuration. The string is used to setup KUBECONFIG_DATA in CircleCI
- bin/promote_app.sh: promote the CURRENT version of app (CREEN candidate) to Production
- bin/push_docker.sh: push the CURRENT version of app (GREEN candidate) image to DockerHub
- bin/setup_first_k8s_app.sh: setup the BLUE environment