Simple examples of how to use kind during development

Linux host or something with Linux that runs docker (might also run on a Pi4-64)
You can access the k8s cluster form outside e.g. developer Windows machine.
Warning: Do not use a public IP of the internet for the API Server
- read kind documentation about this:
- https://kind.sigs.k8s.io/docs/user/configuration/ yellow box

what you get

full feature blown developer k8s
it can expose ports to the host machne
comes with a local registry
can be accessed from a development computer e.g. Windows / Mac running a Linux VM or your home Proxmox/ESXi server
config/examples for ingress, loadbalancers, postgres, persistant volumes
hello world python app using all of the above

Install Kind

install go: https://go.dev/doc/install
fast lane:

get_latest_release() {
  curl --silent "https://api.github.com/repos/$1/releases/latest" | # Get latest release from GitHub api
    grep '"tag_name":' |                                            # Get tag line
    sed -E 's/.*"([^"]+)".*/\1/'                                    # Pluck JSON value
}
KIND_LATEST=$(get_latest_release kubernetes-sigs/kind)
ARCH=$(dpkg --print-architecture 2>/dev/null || echo "amd64")

curl -Lo ./kind https://kind.sigs.k8s.io/dl/${KIND_LATEST}/kind-linux-${ARCH}
chmod +x ./kind
sudo mv ./kind /usr/local/bin/kind

Create the cluster

$ make cluster

Feature loadbalancer

# metallb takes some time to load - so it's disable by default
$ make feature-loadbalancer

Storage path

# default shared volume $(PWD)/data but you can add your own
$ make cluster DATAPATH=/foo/bar

Multiple instances

# in case you need multiple instances
$ make cluster DATAPATH=/foo/bar CLUSTER_NAME=my-other-kind REGISTRY_PORT=5003 PUBLIC_HTTP_PORT=8090 PUBLIC_HTTPS_PORT=8091

Applications

Installs the k8s Dashboard. It also creates a user for the dashboard. Kubeclt proxy is used to forward the dashboard.

The dashboard is available here < http://localhost:8001/api/v1/namespaces/kubernetes-dashboard/services/https:kubernetes-dashboard:/proxy/>. The commmand also shows the required token for a login.

$ make dashboard-connect

Installs a postgress server with a persistant volume. Full feature blown example with secrets storage and configuration variables. It allows an internal connect with host "postgres".

$ make postgres
$ make remove-postgres # kill postgres - but keep persistant storage

Runs an ubuntu machine in the cluster for doing all sorts of interessting things e.g. debugging and investigating.

$ make k8sshell

Builds and runs a python sample application. It connects to postgres and displays the version.

$ make postgres # ensure it's running
$ make webapp
$ curl localhost:8000/webapp
$ make remove-webapp # kill the webapp
$ make webapp-replicas # using replicas
$ curl localhost:8000/webapp
$ make remove-webapp # kill the webapp
$ make remove-postgres # we can shut it down

Examples

Simple example showing features.

Persistant storage examples. There is shared storage between all nodes and worker storage that is per node only.

As default $(PWD)/data is used. At cluster create time DATAPATH can be used to have a custom directory.

$ make example-storage
$ kubectl exec -it storage-pod -- /bin/ls -la /storage/shared /storage/worker
$ make remove-example-storage

Ingress is an inverse proxy. This example shows how to expose a pods content to the world device. We use worker node 1 as public device of the kind cluster and have exported these ports as default during kind cration phase:

PUBLIC_HTTP_PORT?=8000
PUBLIC_HTTPS_PORT?=8443

This example starts two pods and puts them in the path /foo and bar of the public http port.

$ make example-ingress
$ curl localhost:8000/foo
$ curl localhost:8000/bar
$ make remove-example-ingress

The load balancer offers an internal loadbalancer for a webservice, that is not exposed to a public port. For reason to make the cluster creation faster, the loadbalancer isn't applyied. You need do to this by make feature-loadbalancer.

$ make example-loadbalancer
$ make k8sshell
$ # apt update && apt get install curl && curl foo-service:5678
$ # > you see foo / bar cycling
$ make remove-example-loadbalancer

egandro / k8s-kind