Kind — Kubernetes in Docker

Kubernetes

Published

May 16, 2025

Modified

May 28, 2025

Overview

Kind¹ (Kubernetes IN Docker)

…run Kubernetes clusters in Docker containers
…primarily used for local testing and development purposes
…supports the creation of multi-node clusters
…allows testing against multiple Kubernetess versions
…test different configuration with multiple clusters
…support for persistent volumes …no loadbalancer …no ingress
Maintained by the Kubernetes community…
- …dedicated Kubernetes SIG (Special Interest Group)
- …focuses on testing and quality assurance for Kubernetes
- …find the Kind repository on GitHub²

Keep Calm and Load Balance on KIND³, Antonio Ojea & Benjamin Elder, Google, KubeCon (2024)

Installation

Prerequisites…

…ensure Docker is installed⁴ & Docker daemon is running
…kubectl⁵ to interact with the Kubernetes cluster

Installation⁶…

# install Kind in the user home-directory
test -d ~/bin || mkdir ~/bin ; export PATH=$PATH:~/bin
curl -L https://kind.sigs.k8s.io/dl/v0.27.0/kind-linux-amd64 -o ~/bin/kind
chmod +x ~/bin/kind

# verify the installation
kind version

…or use the script kind-install⁷

Usage

Simple example of multiple clusters…

# create clusters
kind create cluster --name alpha
kind create cluster --name beta

# list running clusters
kind get clusters

# switch configuration context between clusters
kubectl config use-context kind-alpha

# remove a cluster
kind delete cluster --name beta

Configuration

Kind supports to specify various settings by configuration file⁸…

…for example number of nodes, networking options,etc
Why use a configuration file?
- Documentation …servers a documentation of the setup
- Reproducibility …recreate the same setup consistently
- Version control …provides a setup for collaboration
- Automation …simplify CI/CD integration

Create a multi-node cluster from a configuration file

# simple configuration file example
cat > kind-config.yaml <<EOF
kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
name: alpha
nodes:
- role: control-plane
- role: worker
- role: worker
EOF

# create a cluster using a configuration file
kind create cluster --config kind-config.yaml

# verify the number of nodes
kubectl get nodes

`kind load`

Load a container image into the cluster⁹:

# create a container image
cat > Dockerfile <<EOF
FROM debian:latest
CMD ["sleep", "3000"]
EOF
docker build -t sleep:latest .

# start a cluster
Kind create cluster

# load the image into the cluster
kind load docker-image sleep:latest

# use the image
kubectl apply -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: sleep
  spec:
    containers:
    - name: sleep
      image: sleep:latest
      imagePullPolicy: Never  # required if using latest
EOF

Do not use the :latest tag or specify imagePullPolicy: Never

# create a named cluster
name=alpha ; kind create cluster --name $name

# container image with a specific version
docker build -t sleep:0.1 .

# upload the container image to the cluster
kind load docker-image --name $name sleep:0.1

# list images present on the cluster node
docker exec -it $name-control-plane crictl images

Network

Kind cluster leverages Docker’s networking…

…alongside standard Kubernetes components
Kind Kubernetes nodes in Docker containers…
- …share the same Linux network namespace
- …communication over a Docker bridge network

# example is running two Kind clusters
>>> kind get clusters               
alpba
delta

# The `kind` bridge running on the host
>>> docker network list
NETWORK ID     NAME      DRIVER    SCOPE
#…
ba3abde46bfb   kind      bridge    local

A Linux bridge behaves like a network switch…

>>> docker inspect kind
#…
                "Name": "alpba-control-plane",
                "IPv4Address": "172.18.0.5/16",

#…
                "Name": "delta-control-plane",
                "IPv4Address": "172.18.0.2/16",

Lightweight networking with kindnetd¹⁰ …no load-balancer, ingress

Port Forwarding

kubectl create deployment nginx --image nginx
kubectl expose deployment nginx --name nginx --type NodePort --port 80
kubectl port-forward service/nginx 8000:80
$BROWSER localhost:8000

Port Mapping

cat <<EOF | kind create cluster --config=-
kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
nodes:
- role: control-plane
  extraPortMappings:
  - containerPort: 30080
    hostPort: 8080
    protocol: TCP
EOF

kubectl run nginx --image=nginx --port=80

# service IP within the cluster
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Service
metadata:
  labels:
    run: nginx
  name: nginx
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
    nodePort: 30080
  selector:
    run: nginx
  type: NodePort
status:
  loadBalancer: {}
EOF

Cloud Provider

sudo dnf install golang
go install sigs.k8s.io/cloud-provider-kind@latest
install ~/go/bin/cloud-provider-kind ~/bin

cloud-provider-kind¹¹ …monitors all Kind clusters…

…reacts to services of type LoadBalancer
…creates a corresponding container to expose the service

# start a cluster
kind create cluster
# start the cloud provider
cloud-provider-kind

Allow load-balancing of workloads on a control plane node…

kubectl label node $name-control-plane node.kubernetes.io/exclude-from-external-load-balancers-

apiVersion: v1
kind: Service
metadata:
  #…
spec:
  type: LoadBalancer
  externalTrafficPolicy: Local
  #…

Kubernetes Dashboard

helm repo add kubernetes-dashboard https://kubernetes.github.io/dashboard/
helm install dashboard kubernetes-dashboard/kubernetes-dashboard --namespace kubernetes-dashboard --create-namespace

# wait for all containers
kubectl -n kubernetes-dashboard get pods

kubectl -n kubernetes-dashboard port-forward svc/dashboard-kong-proxy 8443:443 &
$BROWSER https://localhost:8443

# create a user to access the dashboard
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: ServiceAccount
metadata:
  name: admin-user
  namespace: kubernetes-dashboard
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: admin-user
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: admin-user
  namespace: kubernetes-dashboard
EOF
kubectl -n kubernetes-dashboard create token admin-user

Prometheus

Install Promtheus from a Helm chart…

helm add prometheus-community https://prometheus-community.github.io/helm-charts
helm repo update
helm install -n prometheus --create-namespace prometheus prometheus-community/prometheus

…start port forwarding to access the Prometheus dashboard:

prometheus_pod=$(kubectl get pods --namespace prometheus -l "app.kubernetes.io/name=prometheus" -o name)
kubectl --namespace prometheus port-forward $prometheus_pod 9090

Footnotes

Kind Documentation
https://kind.sigs.k8s.io ↩︎
Kind, GitHub
https://github.com/kubernetes-sigs/kind ↩︎
Keep Calm and Load Balance on KIND - Antonio Ojea & Benjamin Elder, Google, Kubecon 2024
https://www.youtube.com/watch?v=U6_-y24rJnI ↩︎
Install Docker Engine, Docker Documentation
https://docs.docker.com/engine/install ↩︎
Install Tools, Kubernetes Documentation
https://kubernetes.io/docs/tasks/tools/↩︎
Installation, Kind Documentation
https://kind.sigs.k8s.io/docs/user/quick-start#installation ↩︎
kind-install script, GitHub
https://github.com/vpenso/scripts/blob/master/bin/kind-install ↩︎
Kind Configuration, Kind Documentation
https://kind.sigs.k8s.io/docs/user/configuration ↩︎
Loading an Image Into Your Cluster, Kind Documentation https://kind.sigs.k8s.io/docs/user/quick-start/#loading-an-image-into-your-cluster ↩︎
Kindnet Project
https://kindnet.es
https://github.com/aojea/kindnet ↩︎
Cloud provider for KIND clusters, GitHub
https://github.com/kubernetes-sigs/cloud-provider-kind ↩︎

--- title: Kind — Kubernetes in Docker categories: - Kubernetes date: 2025/05/16 date-modified: 2025/05/28 toc-expand: 3 toc-depth: 4 --- ### Overview Kind[^ol7GH] (Kubernetes IN Docker) [^ol7GH]: Kind Documentation <https://kind.sigs.k8s.io> - …run Kubernetes clusters in Docker containers - …primarily used for local testing and development purposes - …supports the creation of **multi-node clusters** - …allows testing against multiple Kubernetess versions - …test different configuration with **multiple clusters** - …support for persistent volumes **…no loadbalancer …no ingress** - Maintained by the Kubernetes community… - …dedicated Kubernetes SIG (Special Interest Group) - …focuses on testing and quality assurance for Kubernetes - …find the Kind repository on GitHub[^1SDf7] [^1SDf7]: Kind, GitHub <https://github.com/kubernetes-sigs/kind> ![Keep Calm and Load Balance on KIND[^g56Fg], Antonio Ojea & Benjamin Elder, Google, KubeCon (2024)](kind-architecture.png) [^g56Fg]: Keep Calm and Load Balance on KIND - Antonio Ojea & Benjamin Elder, Google, Kubecon 2024 <https://www.youtube.com/watch?v=U6_-y24rJnI> ### Installation Prerequisites… - …ensure Docker is installed[^4RFd1] & Docker daemon is running - …`kubectl`[^6l34D] to interact with the Kubernetes cluster [^4RFd1]: Install Docker Engine, Docker Documentation <https://docs.docker.com/engine/install> [^6l34D]: Install Tools, Kubernetes Documentation <https://kubernetes.io/docs/tasks/tools/> Installation[^90OLd]… [^90OLd]: Installation, Kind Documentation <https://kind.sigs.k8s.io/docs/user/quick-start#installation> ```bash # install Kind in the user home-directory test -d ~/bin || mkdir ~/bin ; export PATH=$PATH:~/bin curl -L https://kind.sigs.k8s.io/dl/v0.27.0/kind-linux-amd64 -o ~/bin/kind chmod +x ~/bin/kind # verify the installation kind version ``` …or use the script `kind-install`[^gJk1S] [^gJk1S]: `kind-install` script, GitHub <https://github.com/vpenso/scripts/blob/master/bin/kind-install> ## Usage Simple example of multiple clusters… ```bash # create clusters kind create cluster --name alpha kind create cluster --name beta # list running clusters kind get clusters # switch configuration context between clusters kubectl config use-context kind-alpha # remove a cluster kind delete cluster --name beta ``` ### Configuration Kind supports to specify various settings by configuration file[^0OPls]… - …for example number of nodes, networking options,etc - _Why use a configuration file?_ - **Documentation** …servers a documentation of the setup - **Reproducibility** …recreate the same setup consistently - **Version control** …provides a setup for collaboration - **Automation** …simplify CI/CD integration [^0OPls]: Kind Configuration, Kind Documentation <https://kind.sigs.k8s.io/docs/user/configuration> Create a multi-node cluster from a configuration file ```bash # simple configuration file example cat > kind-config.yaml <<EOF kind: Cluster apiVersion: kind.x-k8s.io/v1alpha4 name: alpha nodes: - role: control-plane - role: worker - role: worker EOF # create a cluster using a configuration file kind create cluster --config kind-config.yaml # verify the number of nodes kubectl get nodes ``` ### `kind load` Load a container image into the cluster[^4fG21]: [^4fG21]: Loading an Image Into Your Cluster, Kind Documentation <https://kind.sigs.k8s.io/docs/user/quick-start/#loading-an-image-into-your-cluster> ```bash # create a container image cat > Dockerfile <<EOF FROM debian:latest CMD ["sleep", "3000"] EOF docker build -t sleep:latest . # start a cluster Kind create cluster # load the image into the cluster kind load docker-image sleep:latest # use the image kubectl apply -f - <<EOF apiVersion: v1 kind: Pod metadata: name: sleep spec: containers: - name: sleep image: sleep:latest imagePullPolicy: Never # required if using latest EOF ``` **Do not use the `:latest` tag or specify `imagePullPolicy: Never`** ```bash # create a named cluster name=alpha ; kind create cluster --name $name # container image with a specific version docker build -t sleep:0.1 . # upload the container image to the cluster kind load docker-image --name $name sleep:0.1 # list images present on the cluster node docker exec -it $name-control-plane crictl images ``` ## Network Kind cluster leverages Docker’s networking… - …alongside standard Kubernetes components - Kind Kubernetes nodes in Docker containers… - …share the same Linux network namespace - …communication over a Docker bridge network ```bash # example is running two Kind clusters >>> kind get clusters alpba delta # The `kind` bridge running on the host >>> docker network list NETWORK ID NAME DRIVER SCOPE #… ba3abde46bfb kind bridge local ``` A Linux bridge behaves like a network switch… ```bash >>> docker inspect kind #… "Name": "alpba-control-plane", "IPv4Address": "172.18.0.5/16", #… "Name": "delta-control-plane", "IPv4Address": "172.18.0.2/16", ``` Lightweight networking with `kindnetd`[^fg5H2] …no load-balancer, ingress [^fg5H2]: Kindnet Project <https://kindnet.es> <https://github.com/aojea/kindnet> ### Port Forwarding ```bash kubectl create deployment nginx --image nginx kubectl expose deployment nginx --name nginx --type NodePort --port 80 kubectl port-forward service/nginx 8000:80 $BROWSER localhost:8000 ``` ### Port Mapping ```bash cat <<EOF | kind create cluster --config=- kind: Cluster apiVersion: kind.x-k8s.io/v1alpha4 nodes: - role: control-plane extraPortMappings: - containerPort: 30080 hostPort: 8080 protocol: TCP EOF ``` ```bash kubectl run nginx --image=nginx --port=80 # service IP within the cluster cat <<EOF | kubectl apply -f - apiVersion: v1 kind: Service metadata: labels: run: nginx name: nginx spec: ports: - port: 80 protocol: TCP targetPort: 80 nodePort: 30080 selector: run: nginx type: NodePort status: loadBalancer: {} EOF ``` ### Cloud Provider ```bash sudo dnf install golang go install sigs.k8s.io/cloud-provider-kind@latest install ~/go/bin/cloud-provider-kind ~/bin ``` `cloud-provider-kind`[^2sWdi] …monitors all Kind clusters… - …reacts to services of type `LoadBalancer` - …creates a corresponding container to expose the service [^2sWdi]: Cloud provider for KIND clusters, GitHub <https://github.com/kubernetes-sigs/cloud-provider-kind> ```bash # start a cluster kind create cluster # start the cloud provider cloud-provider-kind ``` Allow load-balancing of workloads on a control plane node… ```bash kubectl label node $name-control-plane node.kubernetes.io/exclude-from-external-load-balancers- ``` ```yaml apiVersion: v1 kind: Service metadata: #… spec: type: LoadBalancer externalTrafficPolicy: Local #… ``` # Kubernetes Dashboard ```bash helm repo add kubernetes-dashboard https://kubernetes.github.io/dashboard/ helm install dashboard kubernetes-dashboard/kubernetes-dashboard --namespace kubernetes-dashboard --create-namespace # wait for all containers kubectl -n kubernetes-dashboard get pods kubectl -n kubernetes-dashboard port-forward svc/dashboard-kong-proxy 8443:443 & $BROWSER https://localhost:8443 # create a user to access the dashboard cat <<EOF | kubectl apply -f - apiVersion: v1 kind: ServiceAccount metadata: name: admin-user namespace: kubernetes-dashboard --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: name: admin-user roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: cluster-admin subjects: - kind: ServiceAccount name: admin-user namespace: kubernetes-dashboard EOF kubectl -n kubernetes-dashboard create token admin-user ``` # Prometheus Install Promtheus from a Helm chart… ```bash helm add prometheus-community https://prometheus-community.github.io/helm-charts helm repo update helm install -n prometheus --create-namespace prometheus prometheus-community/prometheus ``` …start port forwarding to access the Prometheus dashboard: ```bash prometheus_pod=$(kubectl get pods --namespace prometheus -l "app.kubernetes.io/name=prometheus" -o name) kubectl --namespace prometheus port-forward $prometheus_pod 9090 ```