kubectl vs json api for customdefinition or operator - kubernetes

Question

is it possible to use json api instead of all kubectl commands.
Also how would be update a resource or custom definition in that case.

Answer 1

You could take a look at API client libraries.
To call the Kubernetes API from a programming language, you can use client libraries. Officially supported client libraries:
Kubernetes Go client library
Kubernetes Python client library
Kubernetes Java client library
Kubernetes JavaScript client library
To write applications using the Kubernetes REST API, you do not need to implement the API calls and request/response types yourself. You can use a client library for the programming language you are using.
Client libraries often handle common tasks such as authentication for you. Most client libraries can discover and use the Kubernetes Service Account to authenticate if the API client is running inside the Kubernetes cluster, or can understand the kubeconfig file format to read the credentials and the API Server address.
The two paths that support extending the API with custom resources are:
CustomResourceDefinition for basic CRUD needs.
aggregator for a full set of Kubernetes API semantics to
implement their own apiserver.
For example there is a way of creating crd resource with python and some code examples.
list all pods
from kubernetes import client, config
# Configs can be set in Configuration class directly or using helper utility
config.load_kube_config()
v1 = client.CoreV1Api()
print("Listing pods with their IPs:")
ret = v1.list_pod_for_all_namespaces(watch=False)
for i in ret.items:
print("%s\t%s\t%s" % (i.status.pod_ip, i.metadata.namespace, i.metadata.name))
watch on namespace object:
from kubernetes import client, config, watch
# Configs can be set in Configuration class directly or using helper utility
config.load_kube_config()
v1 = client.CoreV1Api()
count = 10
w = watch.Watch()
for event in w.stream(v1.list_namespace, _request_timeout=60):
print("Event: %s %s" % (event['type'], event['object'].metadata.name))
count -= 1
if not count:
w.stop()
print("Ended.")
More examples can be found in examples folder.