Kubernetes CRUD using Python
Kubernetes is a popular container orchestration platform that provides a powerful API for managing containerized applications. The Kubernetes API is a RESTful interface that allows you to interact with Kubernetes clusters programmatically. In this blog post, we will explore how to access Kubernetes API using Python.
Prerequisites
Before we get started, you will need the following:
- A Kubernetes cluster
- Python installed on your local machine
- The kubernetes Python package installed
Enabling Kubernetes under Docker Desktop
Installing Kubernetes package using PIP
pip3 install kubernetes
First, you need to install the kubernetes package using pip. You can do this by running the following command in your terminal:
Listing the Kubernetes Nodes
kubectl get nodes
NAME STATUS ROLES AGE VERSION
docker-desktop Ready control-plane 7d18h v1.25.4
ajeetsraina@Ajeets-MacBook-Pro ~ %
Deploying hellowhale app
kubectl create deployment hellowhale --image ajeetraina/hellowhale
deployment.apps/hellowhale created
Listing the Deployment
kubectl get deploy
NAME READY UP-TO-DATE AVAILABLE AGE
hellowhale 1/1 1 1 12s
Accessing the Deployment using Python
To get started, you need to configure the client to connect to your Kubernetes cluster. You can do this using the config.load_kube_config() method, which loads the Kubernetes configuration from the default configuration file located at $HOME/.kube/config. If you are using a different configuration file or a different location, you can pass the path to the configuration file to the config.load_kube_config() method.
Here is an example of how to configure the client:
from kubernetes import client, config
config.load_kube_config()
api = client.CoreV1Api()
This code loads the Kubernetes configuration from the default configuration file and creates a CoreV1Api object, which provides access to the Kubernetes API.
Listing all the deployments in the default namespace
To list all the deployments in the default namespace, you can use the AppsV1Api().list_namespaced_deployment(namespace) method:
from kubernetes import client, config
config.load_kube_config()
api = client.AppsV1Api()
deployments = api.list_namespaced_deployment(namespace='default')
for deployment in deployments.items:
print(deployment.metadata.name)
This will print the names of all the deployments in the default namespace.
python3 fetch.py
hellowhale
ajeetsraina@Ajeets-MacBook-Pro ~ % cat fetch.py
from kubernetes import client, config
config.load_kube_config()
api = client.AppsV1Api()
deployments = api.list_namespaced_deployment(namespace='default')
for deployment in deployments.items:
print(deployment.metadata.name)
Creating Kubernetes Objects
To create a new Kubernetes object, you can use the appropriate class from the kubernetes.client module and call the appropriate method on the API object.
For example, to create a new deployment, you can use the AppsV1Api().create_namespaced_deployment(namespace, body) method:
from kubernetes import client, config
config.load_kube_config()
api = client.AppsV1Api()
deployment = client.V1Deployment(
api_version="apps/v1",
kind="Deployment",
metadata=client.V1ObjectMeta(
name="my-deployment"
),
spec=client.V1DeploymentSpec(
replicas=3,
selector=client.V1LabelSelector(
match_labels={
"app": "my-app"
}
),
template=client.V1PodTemplateSpec(
metadata=client.V1ObjectMeta(
labels={
"app": "my-app"
}
),
spec=client.V1PodSpec(
containers=[
client.V1Container(
name="my-container",
image="nginx"
)
]
)
)
)
)
api.create_namespaced_deployment(namespace='default', body=deployment)
This will create a new deployment called my-deployment with three replicas of the Nginx container.
kubectl get po,deploy,svc
NAME READY STATUS RESTARTS AGE
pod/hellowhale-66b5557c4c-b9nsk 1/1 Running 0 8m22s
pod/my-deployment-b779fc99c-6rkvg 1/1 Running 0 21s
pod/my-deployment-b779fc99c-cb9f6 1/1 Running 0 21s
pod/my-deployment-b779fc99c-vj8hn 1/1 Running 0 21s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/hellowhale 1/1 1 1 8m22s
deployment.apps/my-deployment 3/3 3 3 21s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d18h
ajeetsraina@Ajeets-MacBook-Pro ~ %
Updating Kubernetes Objects
To update an existing Kubernetes object, you can use the appropriate class from the kubernetes.client module and call the appropriate method on the API object.
For example, to update the number of replicas in a deployment, you can use the Apps' V1Api().patch_namespaced_deployment(namespace, name, body) method:
from kubernetes import client, config
config.load_kube_config()
api = client.AppsV1Api()
deployment = api.read_namespaced_deployment(name='my-deployment', namespace='default')
deployment.spec.replicas = 5
api.patch_namespaced_deployment(name='my-deployment', namespace='default', body=deployment)
This will update the number of replicas in the my-deployment deployment to 5.
kubectl get po,deploy,svc
NAME READY STATUS RESTARTS AGE
pod/hellowhale-66b5557c4c-b9nsk 1/1 Running 0 10m
pod/my-deployment-b779fc99c-67clb 1/1 Running 0 7s
pod/my-deployment-b779fc99c-6rkvg 1/1 Running 0 2m43s
pod/my-deployment-b779fc99c-8vw96 1/1 Running 0 7s
pod/my-deployment-b779fc99c-cb9f6 1/1 Running 0 2m43s
pod/my-deployment-b779fc99c-vj8hn 1/1 Running 0 2m43s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/hellowhale 1/1 1 1 10m
deployment.apps/my-deployment 5/5 5 5 2m43s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d18h
ajeetsraina@Ajeets-MacBook-Pro ~ %
Deleting Kubernetes Objects
To delete a Kubernetes object, you can use the appropriate class from the kubernetes.client module and call the appropriate method on the API object.
For example, to delete a deployment, you can use the AppsV1Api().delete_namespaced_deployment(name, namespace) method:
from kubernetes import client, config
config.load_kube_config()
api = client.AppsV1Api()
api.delete_namespaced_deployment(name='my-deployment', namespace='default')
This will delete the my-deployment deployment.
kubectl get po,svc,deploy
NAME READY STATUS RESTARTS AGE
pod/hellowhale-66b5557c4c-b9nsk 1/1 Running 0 13m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 7d18h
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/hellowhale 1/1 1 1 13m
ajeetsraina@Ajeets-MacBook-Pro ~ %
Conclusion
In this blog post, we have explored how to access the Kubernetes API using Python. We covered how to configure the client, how to get, create, update, and delete Kubernetes objects. The kubernetes package provides a Pythonic interface to the Kubernetes API, making it easy to work with Kubernetes resources from within your Python code.
While this blog post provides a brief introduction to accessing the Kubernetes API with Python, there is much more that can be done. The Kubernetes API provides a rich set of features for managing containerized applications, and the kubernetes package provides a comprehensive set of classes and methods for interacting with the API. With the knowledge and tools presented here, you can begin building your own Python scripts and applications for managing your Kubernetes clusters.