andrewguest / Kubernetes-example

Examples of Kubernetes configs

Fullstack web app deployed to Kubernetes

This is meant to be an example and reference for how to create and deploy a fullstack application to Kubernetes. It's also meant to explain the different components of Kubernetes.

You don't need to build these images, because they're available on Docker Hub but if you want to build them for yourself then there's a Dockerfile in each directory.

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Component	Description
Pod	Pods in Kubernetes run a container or containers. They are the smallest "unit" in Kubernetes.
Deployment	A deployment tells Kubernets what image or images to run inside the pod, how many pods you want (replicas), what port or ports to expose on the pod and plenty of other information.
Service	A service creates a single, constant point of entry to a deployment. Basically, a service is needed to access your pods from outside Kubernetes or to loadbalance between groups of pods.
Ingress	Ingress exposes HTTP and HTTPS routes from outside the Kubernetes cluster to services within the cluster. This allows you to access routes inside your Kubernetes cluster from outside the cluster.

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Files and their descriptions

To make it easier on me, I've broken each Kubernetes component into it's own file even though this means more files and more commands to run. The tables below are also setup in the order that I would run the files (top file first, then work your way down).

Frontend

kubectl apply -f ./frontend/frontend-deployment.yaml
kubectl apply -f ./frontend/frontend-service.yaml

File	Description
frontend-deployment.yaml	Defines values such as the image to use for the pods, the port(s) to open on the pods, how many pods to start, and the CPU & RAM resources the pod(s) get and their limits.
frontend-service.yaml	Tells Kubernetes to send requests on port 3001 (on the worker nodes) to port 8080 on the 'frontend' pods.

Backend

kubectl apply -f ./backend/backend-deployment.yaml
kubectl apply -f ./backend/backend-service.yaml
kubectl apply -f ./backend/backend-autoscaler.yaml

File	Description
backend-deployment.yaml	Defines values such as the image to use for the pods, the port(s) to open on the pods, how many pods to start, and the CPU & RAM resources the pod(s) get and their limits.
backend-service.yaml	Tells Kubernetes to send requests on port 3000 (on the worker nodes) to port 8000 on the 'backend-api' pods.
backend-autoscaler.yaml	Defines the minimum and maximum number of replicas that Kubernetes should keep running or scale up to and the criteria for scaling up or down.

Traefik

kubectl apply -f ./traefik/traefik-cluster-role.yaml
kubectl apply -f ./traefik/traefik-service-account.yaml
kubectl apply -f ./traefik/traefik-cluster-role-binding.yaml
kubectl apply -f ./traefik/traefik-deployment.yaml
kubectl apply -f ./traefik/traefik-service.yaml
kubectl apply -f ./traefik/traefik-ingress.yaml

File	Description
traefik-cluster-role.yaml	Defines a custom Kubernetes cluster role that service accounts can then be given.
traefik-service-account.yaml	Creates a service account that Traefik can use to manage cluster ingress.
traefik-cluster-role-binding.yaml	Assigns the service account, created in traefik-service-account.yaml, the cluster role defined in traefik-cluster-role.yaml.
traefik-deployment.yaml	Defines values such as the image to use for the pods, the port(s) to open on the pods, how many pods to start, and the CPU & RAM resources the pod(s) get and their limits.
traefik-service.yaml	Tells Kubernetes what port(s) on the k8s worker nodes are tied to what pod port(s).
traefik-ingress.yaml