How to use the command k3d (with examples)
K3d is a command-line tool that allows users to easily create and manage Kubernetes clusters using k3s, a lightweight and efficient Kubernetes distribution, inside Docker. It provides a convenient way to set up local development and testing environments for Kubernetes applications.
Use case 1: Create a cluster
Code:
k3d cluster create cluster_name
Motivation:
Creating a cluster is the first step in setting up a Kubernetes environment. Using the k3d cluster create command, users can quickly create a new cluster with a specified name.
Explanation:
k3d cluster create: This is the command used to create a new k3s cluster.cluster_name: This is the name of the cluster to be created. It should be a unique identifier.
Example output:
INFO[0000] Created cluster network with ID 4c7b3a1943f8cc604a5e72d145cdf4b1620abc0ac1d0ee0df17330a058f99ac8
INFO[0000] Created docker volume "k3d-cluster_name-images"
INFO[0001] Creating cluster [cluster_name]
INFO[0001] Creating server using docker.io/rancher/k3s:v1.21.2-k3s1...
INFO[0001] Pulling image docker.io/rancher/k3s:v1.21.2-k3s1...
INFO[0014] SUCCESS: created cluster [cluster_name]
Use case 2: Delete a cluster
Code:
k3d cluster delete cluster_name
Motivation:
Deleting a cluster is useful when the cluster is no longer needed, or if you want to create a fresh cluster with a clean slate. The k3d cluster delete command allows users to easily delete a cluster by specifying its name.
Explanation:
k3d cluster delete: This is the command used to delete a k3s cluster.cluster_name: This is the name of the cluster to be deleted.
Example output:
INFO[0000] Deleting cluster [cluster_name]
INFO[0000] Deleted cluster [cluster_name]
INFO[0000] The cluster has been removed.
Use case 3: Create a new containerized k3s node
Code:
k3d node create node_name
Motivation:
In a Kubernetes cluster, nodes are the worker machines that run the actual application workloads. The k3d node create command allows users to easily create a new containerized k3s node, which can be added to an existing cluster to scale the capacity of the cluster.
Explanation:
k3d node create: This is the command used to create a new containerized k3s node.node_name: This is the name of the node to be created. It should be a unique identifier.
Example output:
INFO[0000] Creating node [node_name] in cluster [k3d-cluster_name]
INFO[0000] Created volume "k3d-cluster_name-images-node_name"
INFO[0000] Creating docker container [k3d-cluster_name-agent-node_name] ...
INFO[0001] SUCCESS: created node [node_name] in cluster [k3d-cluster_name]
Use case 4: Import an image from Docker into a k3d cluster
Code:
k3d image import image_name --cluster cluster_name
Motivation:
When developing Kubernetes applications, it is often necessary to use custom Docker images. The k3d image import command allows users to easily import an image from Docker into a k3d cluster, making it available for use in their applications.
Explanation:
k3d image import: This is the command used to import an image from Docker into a k3d cluster.image_name: This is the name of the image to be imported.--cluster cluster_name: This flag specifies the name of the k3d cluster where the image should be imported.
Example output:
INFO[0000] Importing image [image_name] into cluster [cluster_name]
INFO[0000] SUCCESS: imported image [image_name] into cluster [cluster_name]
Use case 5: Create a new registry
Code:
k3d registry create registry_name
Motivation:
A registry is a central location where Docker images are stored and can be pulled from. The k3d registry create command allows users to easily create a new registry, which can be used to store and share Docker images within a k3d cluster.
Explanation:
k3d registry create: This is the command used to create a new registry.registry_name: This is the name of the registry to be created. It should be a unique identifier.
Example output:
INFO[0000] Creating registry [registry_name]
INFO[0000] Created registry [registry_name]
INFO[0000] The registry is accessible via:
INFO[0000] - container name: registry_name.localhost
INFO[0000] - URL: docker://registry_name.localhost
Conclusion:
The k3d command-line tool provides a convenient way to create and manage Kubernetes clusters using k3s inside Docker. With the ability to create clusters, delete clusters, create new nodes, import Docker images, and create registries, users have the flexibility to set up and configure their Kubernetes environments for local development and testing.
