this is a template for building a microservice project in kubernetes. This will allow to create multiple microservices communicating with each other, persistent data using mongodb, a functional react app using redux to communicate with the microservices, and a detailed plan to add microservices and deploy to digital ocean.
Link to LucidChart architecture overview

• Template for multiple microservices and how they communicate with each other:
  • example of two services communicating with each other
  • their deployment yaml files
  • the ingress controller file to deploy and route the requests accordingly
  • Working Auth service
• Error handling, middlewares and Models for nodejs in common code:
  • How to handle errors on the microservices
  • Middlewares for different functionalities and their implementation in the microservices
  • Models and their implementation of hashing and class methods
• React setup with Redux:
  • Functional react communicating with microservices
  • Using redux to send requests
• Deployment instruction to digital ocean
  • How to set up digital ocean
  • How to deploy the k8s to the managed kubernetes of digital ocean
  • How to set up persistent data in digital ocean
• What can be still be added
  • MongoDB sharding/distributed across multiple nodes
  • MongoDB replication

##How to start the project

• install Docker desktop and kubernetes
• Install ingress nginx by running this command (Same command as Mac):
  • kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v0.44.0/deploy/static/provider/cloud/deploy.yaml
• overwrite the local host to point to a URL, it should be the same as the host in the ingress controller file:
  • Modify hosts file of widows and write the desired url next to the 127.0.0.1 ip

  1. the host file 127.0.0.1 backend.com

     path: C:\Windows\System32\drivers\etc\hosts

  2. the ingress controller file

  - host: backend.com

• start the desired services/deployments inside the k8s folder and run the ingress-controller file kubectl apply -f <name_of_files>
• you can access the url specified in the host with the specified routes

• how to add a microservice

• Create a new server (using the template if it's a nodejs server) with the desired routes (the routes and port should be unique)
• Dockerize the server and push it to docker hub
• Create a kubernetes deployment and service using the files inside the k8s folder as a template
• Add the database and setup persistent data if needed. Again, use the files inside k8s folder as a template
• Add the microservice to the ingress-controller file, as a new element of the array path, while specifying the correct port, service name, and the path reserved to that service example:

  paths:
    - path: /auth/?(.*)
      backend:
      serviceName: auth-srv
      servicePort: 3000

• Add the commands to stop/deploy the yaml files and docker images in deploy.sh and stop.sh
• run ./scripts/stop_deploy.sh

• Errors

all errors will be handled by error-handler.js all we need to do is import it in index.js file:

app.use(error_handler);

• Midllewares

• error-handler.js is a middleware to handle all of the errors inside the nodejs servers

• require-auth.js is a middleware to get the token from the headers and verify it. Need to be passed for all routes that need auth

• validate-request.js is a middleware that will take the req and throw an error if the params are not correctly setup

• Models

• The models are in the common/models folder. There's the User and Password model to compare different passwords

• go to the types.js file and add the desired enums
• go to the reducer file and add your new reducer file with the logic to handle the enums and state
• add action file and add you logic
• go to the component and bring it

useEffect(() => {
        store.dispatch(load_user());
    }, [])

call this in App.js to load user as soon as they log in the page. We set the deffault header and store the token in local storage

• start kubernetes cluster
• install doctl
• create api key in digital ocean
• doct auth init (from powershell)
• series of commands to connect digital ocean context locally
  • doctl kubernetes cluster kubeconfig save <cluster_name (i.e backend-template)>
    • now we are connected to cloud kubernetes
• install ingress nginx: kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v0.45.0/deploy/static/provider/do/deploy.yaml
• to watch ingress status: kubectl get pods -n ingress-nginx -l app.kubernetes.io/name=ingress-nginx --watch
• to see contexts: kubectl config view
  • to switch context: kubectl config use-context

https://www.mongodb.com/digital-ocean

• create droplet
• ssh into droplet: ssh [email protected]
• install and run
  • wget -qO - https://www.mongodb.org/static/pgp/server-4.4.asc | sudo apt-key add -
  • sudo apt-get install gnupg
  • wget -qO - https://www.mongodb.org/static/pgp/server-4.4.asc | sudo apt-key add -
  • echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu focal/mongodb-org/4.4 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.4.list
  • sudo apt-get update
  • sudo apt-get install -y mongodb-org
  • ps --no-headers -o comm 1
  • sudo service mongod start
  • sudo service mongod status (check the status)
  • sudo service mongod stop (to stop mongodb)
  • sudo service mongod restart (to restart mongodb)
  • mongo (to start the database)
• create an admin user and connect to it
  • use admin

  •   db.createUser({ user: "root", pwd: "root", roles: [ { role: "userAdminAnyDatabase", db: "admin" }, "readWriteAnyDatabase" ]})

  - enable auth
   - sudo vi /etc/mongod.conf
   - uncomment security and add
     ```shell
     ...
     security:
       authorization: "enabled"
     ...
     ```
   - sudo service mongod restart (restard mongodb_
   - To connect
     - mongo -u root -p --authenticationDatabase admin
  

• configure firewall
  • sudo ufw enable
  • sudo ufw allow 27017 or sudo ufw allow from your_trusted_server_ip/32 to any port 27017 (your_trusted_server_ip=)
  • sudo ufw status -configure mongo to listen to remote server
    • sudo vi /etc/mongod.conf
    • add the droplet server ip

      # network interfaces
      net:
      port: 27017
      bindIp: 127.0.0.1,mongodb_server_ip

    • sudo service mongod restart