Container Orchestration (22%)

Cluster Networking

• A kubernetes cluster consists of master and worker nodes. Each node must have a network interface with a valid IP address configured. Each host must be connected to a network.
• Certain TCP/UDP ports are required to be open:
  • 6443/tcp
  • 10250/tcp
  • 10251/tcp
  • 10252/tcp
  • 2379/tcp
  • 2380/tcp
  • 30000-32767/tcp

Pod Networking

• Every requires an IP address
• Every pod in the cluster should be able to reach every other pod without using NAT

CNI

• Container Network Interface
• Container Network Interface (CNI) is a framework for dynamically configuring networking resources. It uses a group of libraries and specifications written in Go. The plugin specification defines an interface for configuring the network, provisioning IP addresses, and maintaining connectivity with multiple hosts.

DNS

• Domain Name Service
• Used to resolve names to IP addresses
• CoreDNS is the default DNS service used in Kubernetes

Ingress

Services

• Services are like a load balancer. They load balance traffic to backend pods (referred to as endpoints)
• There are 3 types of services in Kubernetes
  • ClusterIP
    • the default
    • The service IP address is only available inside the cluster
  • NodePort
    • Makes the service accessible on a predefined port on all nodes in the cluster
  • LoadBalancer
    • Provisions a load balancer in a cloud environment to make the service accessible

Sidecars

• Sidecars are a secondary container running inside our pod that provide a service for the primary pod
• An example is a container in our pod that ships logs to an external service for the business-logic container

Envoy

Storage