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Orchestrating Collections of Services with Kubernetes

  • Install Kubernets on linux

  • Whirlwind of Kubernetes

    • Terms of Kubernetes
      • Kubernetes Cluster: A collection of nodes + a master to manage them
      • Node: a virtual machine that will run our containers
      • Pod: More or less a running container. Technically, a pod can run multiple containers
      • Deployment: Monitors a set of pods, make sure they are running, and restarts them if they crash
      • Service : Provides an easy to remember URL to access a running container
      • Config file
        • run x copies of pods
        • Please allow copies of posts to be accessiable from network

  • Pod:Pods are the smallest deployable units of computing that you can create and manage in Kubernetes. A Pod (as in a pod of whales or pea pod) is a group of one or

    • commands with Pod
      command opeation
      kubecetl exec -it posts sh go inside the pod container
      kubectl log posts show logs
      kubcetl delete posts delete pod
      kubectl apply -f conf file start the pod
      kubectl describe pod posts get pod's inforamation

    Usually, we don't create pods. we create deployment

  • Introduction to deployment

    • why and what is pod
      • Manage the containers inside a Pod
      • To switch the new version of image(CI/CD)
      • manage a group of pods
    • updating pod
      • #1 Build new images and update the k8s config file. Then run apply configure file again
        • created => configured
        • Every change may bring error, it would be great to tell kubernets always to use the latest version of images
      • #2
        • register docker and login in your docker from your local terminal
        • rebuild latest image
        • push image to docker hub
        docker push dockeraccount/repo:tag
        • rollout the deployment
        kubectl rollout restart deployment [name]
    • assign pods to node
      You can constrain a Pod so that it can only run on particular set of Node(s).

  • networking service
    Services provide networking between pods

    • types of services
      • Cluster IP: Setup an easy to remember URL to access a pod, only expose pods in the cluster(Internal)
      • Node Port: Make a pod accessible outside of the cluster. usually, only used for dev purpose
      • Load balancer: Make a pod accessibale from outside of the cluster. This is the right way to expose a pod t othe outside world
      • External Name: Redirects an in-cluster request to a CNAME url

  • colocated deployment with service in a deployment yaml file

  • React app want to access endpoint to multiple services

    • Problem and solutions
      • NodePort port value is generated randomly
      • route the request to a specified port
    • Terms
      • Load Balancer Service
        Tells K8s to reach out to its provider and provision a load balancer. Gets traffict into a single pod
      • Ingress or Ingress Controlloer
        A pod with a set of routing rules to distribute traffic to other services

  • Load balancer services and Ingress

  • Skaffold

    • for deployment in production
      build image -> upload image -> rollout start deployment
    • for deployment in development
      that is cumbersome