Kubernetes

• Used to run a bunch of various docker containers, and have them communicate with each other.
• Deployments.
  • For scaling, can make sure that a certain number of pods are running an image.
  • It can also manage the upgrading of pods.
  • Defined through a configuration file.
• Services provide networking between pods, and allow ports to be reached from the outside world.
  • Cluster IP services sets up communication for the nodes in a cluster to communicate with each other.
    • Within our services, we can request to other services by using http:// followed by the name of the service.
  • Node ports allow a pod to be accessible from outside of the cluster (usually only used for dev purposes).
  • Load balancers route and expose a cluster’s pods to the outside world.
    • The load balancer service isn’t actually created inside our cluster.
    • It directly tells AWS, GCP, Azure to make a load balancer on the cloud service.
  • Ingress/Ingress Controller.
    • Is a service that runs inside the cluster.
    • Has routing rules for redirecting a request to certain pods.

Common pod commands.

kubectl apply -f <config-file>

• Used to spin up a pod based on the configuration file.

kubectl get pods

• List all pods.

kubectl exec -it <pod-name> sh

• Open a shell into the running pod instance.

kubectl logs <pod-name>

• Print logs from a pod.

kubectl delete pod <pod-name>

• Delete a pod.

kubectl describe pod <pod-name>

• Gives you some info about the pod, including an event log.

Common deployment commands.

• Basically the same as for pods, but just replace pod with deployment.

Updating a deployment.

• Deployment configuration should be set to use the latest tag of our image.
• We should update our image on version latest, upload it to Docker Hub.
• Then just run this:

kubectl rollout restart deployment <depl-name>