jake-shobin / helm-sample-flask-project

Sample projects using helm for deployment

Sample Flask project deploying on Kubernetes

This repository is a sample python Flask app, that can be deployed on Kubernetes using CircleCI. You can use this project as a template to deploy your app on Teko Kubernetes cluster, CI/CD pipeline with CircleCI.

• Flask application
• CI/CD using CircleCI
• Celery
• Redis pubsub

Integration Guide

In order to deploy your app on Kubernetes, some basic knowledge about Kubernetes and Docker is required. The template uses helm to simplify the deployment.

Prerequisites

• Installing kubectl
  • To access Kubernetes cluster, ask SA team to obtain your config file, then place it at $HOME/.kube
• Installing helm
  • Initialize helm using command: helm init --client-only
• An account to access Docker registry and helm chart repository which is Harbor
  • Ask SA team to create your project and account.

Edit your values.yaml

A helm chart is created to simplify deployment: https://github.com/teko-vn/helm-charts/tree/master/flaskapp. Just copy values.yaml then edit its values to your own values.

NOTE: In this repo, values-tpl.yaml is used with a placeholder {{ branch }}. This placeholder will be replaced to deploy your app in different environments. The file is placed at <project_root>/deployments/k8s/ directory to work with Makefile in CI configuration

1. nameOverride, fullnameOverride: Your app name in short and long description. You need to provide both.

2. replicaCount: The number of instances your app will launch.

3. image: Docker Image config

   • registry: Docker image registry. Ex: gcr.io (Google Cloud Container Registry), docker.io (Docker Hub), hub.k8s.teko.vn (Teko Harbor). If you leave this empty, Docker Hub will be used.
   • repository: The path your Docker image. Ex: hello-flask/hell-flask
   • tag: The image tag. Ex: 1.0.0, 1.2.0...
   • port: The container's port.
   • pullPolicy: Image pull policy. Ex: Always, IfNotPresent
   • dockerConfig: docker config json file. The file can be found at $HOME/.docker/config.json after you login to the registry by calling docker login <registry>

4. healthcheck: Health-check

   • enabled: true to enable heath-check.
   • liveness: HTTP URL to check your app's liveness.
   • readiness: HTTP URL to check your app's readiness.
   • host: HTTP host header when calling HTTP GET request to health-check URLs.

5. hosts: An array of your app's hosts.

   • host: your app's host. Ex: myapp.k8s.teko.vn
   • paths: an array of URI paths. Leave it "", so all requests to host will be routed to your service.
   • Example

      - host: myapp.k8s.teko.vn
        paths:
          - "/api"
      - "/api/v1"
     

     so all requests to myapp.k8s.teko.vn/api and myapp.k8s.teko.vn/api/v1 will be routed to your service.

6. secrets: your app's secrets

   It is an array of key-value pair. Example:

   secrets:
     - db-url: "mysql://user:passw@host:3306/mydb"
     - amqp-url: "amqp://user:[email protected]/teko-prod"
   

7. environmentVariables: your app's environment variables.

   It can be a string or a value from your apps' secrets. Example:

   environmentVariables:
   - name: FLASK_CONFIG
     value: production
   - name: DATABASE_URL
     valueFromSecret: db-url
   

Configure CI

Sample CircleCI configuration file at config.yml. A Makefile is created for some commands. You can edit these files to suit your needs.

NOTE: The values file (values-tpl.yaml) edited in previous step should be placed at <project_root>/deployments/k8s/ directory to work with Makefile.

1. Makefile

   You need to provide your project' values, which are at top of the Makefile:

   PROJECT_NAME := hello-flask
   IMAGE_REPO := hub.k8s.teko.vn/hello-flask/hello-flask
   HARBOR_SERVER := https://hub.k8s.teko.vn
   

2. .circleci/config.yml

   There are two workflows configured:

   • feature-development

     When a feature is developed at feature/* branch, it can be deployed at <your-app>-<short-branch-name>.k8s.teko.vn.

     

     When feature is merged to master branch, it can be deployed to staging for UAT testing.

     

   • deploy-production

     When a git tag is created, following semver convention (Ex: v0.1.1, v1.2.0...), your app is ready to deploy on production environment.

     

3. Configure CirleCI environments

   Some environment variables is required to configure at your project CircleCI settings.

   • DEV_KUBE_CONFIG: kubectl config file for k8s development cluster. This value must be base64 encoded.
   • PROD_KUBE_CONFIG: kubectl config file for k8s production cluster. This value must be base64 encoded.
   • HARBOR_USERNAME: Harbor username, which is needed to use Teko Harbor for image registry and flaskapp helm chart.
   • HARBOR_PASSWORD: Harbor password, which is needed to use Teko Harbor for image registry and flaskapp helm chart.