k3d/docs/examples.md

Examples

Expose services

1. via Ingress

In this example, we will deploy a simple nginx webserver deployment and make it accessible via ingress. Therefore, we have to create the cluster in a way, that the internal port 80 (where the traefik ingress controller is listening on) is exposed on the host system.

1. Create a cluster, mapping the ingress port 80 to localhost:8081

   k3d create --api-port 6550 --publish 8081:80 --workers 2

   • Note: --api-port 6550 is not required for the example to work. It's used to have k3s's API-Server listening on port 6550 with that port mapped to the host system.

2. Get the kubeconfig file

   export KUBECONFIG="$(k3d get-kubeconfig --name='k3s-default')"

3. Create a nginx deployment

   kubectl create deployment nginx --image=nginx

4. Create a ClusterIP service for it

   kubectl create service clusterip nginx --tcp=80:80

5. Create an ingress object for it with kubectl apply -f Note: k3s deploys traefik as the default ingress controller

   apiVersion: extensions/v1beta1
   kind: Ingress
   metadata:
     name: nginx
     annotations:
       ingress.kubernetes.io/ssl-redirect: "false"
   spec:
     rules:
     - http:
         paths:
         - path: /
           backend:
             serviceName: nginx
             servicePort: 80
   

6. Curl it via localhost

   curl localhost:8081/

2. via NodePort

1. Create a cluster, mapping the port 30080 from worker-0 to localhost:8082

   k3d create --publish 8082:30080@k3d-k3s-default-worker-0 --workers 2

   • Note: Kubernetes' default NodePort range is 30000-32767

... (Steps 2 and 3 like above) ...

1. Create a NodePort service for it with kubectl apply -f

   apiVersion: v1
   kind: Service
   metadata:
     labels:
       app: nginx
     name: nginx
   spec:
     ports:
     - name: 80-80
       nodePort: 30080
       port: 80
       protocol: TCP
       targetPort: 80
     selector:
       app: nginx
     type: NodePort
   

2. Curl it via localhost

   curl localhost:8082/

Running on filesystems k3s doesn't like (btrfs, tmpfs, …)

The following script leverages a Docker loopback volume plugin to mask the problematic filesystem away from k3s by providing a small ext4 filesystem underneath /var/lib/rancher/k3s (k3s' data dir).

#!/bin/bash -x

CLUSTER_NAME="${1:-k3s-default}"
NUM_WORKERS="${2:-2}"

setup() {
  PLUGIN_LS_OUT=`docker plugin ls --format '{{.Name}},{{.Enabled}}' | grep -E '^ashald/docker-volume-loopback'`
  [ -z "${PLUGIN_LS_OUT}" ] && docker plugin install ashald/docker-volume-loopback DATA_DIR=/tmp/docker-loop/data
  sleep 3
  [ "${PLUGIN_LS_OUT##*,}" != "true" ] && docker plugin enable ashald/docker-volume-loopback

  K3D_MOUNTS=()
  for i in `seq 0 ${NUM_WORKERS}`; do
    [ ${i} -eq 0 ] && VOLUME_NAME="k3d-${CLUSTER_NAME}-server" || VOLUME_NAME="k3d-${CLUSTER_NAME}-worker-$((${i}-1))"
    docker volume create -d ashald/docker-volume-loopback ${VOLUME_NAME} -o sparse=true -o fs=ext4
    K3D_MOUNTS+=('-v' "${VOLUME_NAME}:/var/lib/rancher/k3s@${VOLUME_NAME}")
  done
  k3d c -i rancher/k3s:v0.9.1 -n ${CLUSTER_NAME} -w ${NUM_WORKERS} ${K3D_MOUNTS[@]}
}

cleanup() {
  K3D_VOLUMES=()
  k3d d -n ${CLUSTER_NAME}
  for i in `seq 0 ${NUM_WORKERS}`; do
    [ ${i} -eq 0 ] && VOLUME_NAME="k3d-${CLUSTER_NAME}-server" || VOLUME_NAME="k3d-${CLUSTER_NAME}-worker-$((${i}-1))"
    K3D_VOLUMES+=("${VOLUME_NAME}")
  done
  docker volume rm -f ${K3D_VOLUMES[@]}
}

setup
#cleanup