How can I get a list of all namespaces within a specific Kubernetes cluster, using the Kubernetes API?

Question

I need to get a list of all namespaces in a specifc Kubernetes cluster, using the Kubernetes API. Because I need to loop through multiple clusters in my Python program, I need to specify the cluster every time I call the API.

One option is to use list_namespace(), as described in https://github.com/kubernetes-client/python/blob/master/kubernetes/docs/CoreV1Api.md

However, this API doesn't allow me to specify the cluster. It picks up the cluster from the current-context in my .kube config file. If I remove or rename the config file, the API call fails completely.

I also found an extensions API at https://github.com/kubernetes-client/python/blob/master/kubernetes/docs/ExtensionsV1beta1Api.md

Unfortunately, there is no API there to retrieve a list of namespaces. Is there some other API that I am unaware of?

Answer 1

If you see the source code of the kube_config module you can use different arguments with the method load_kube_config to select your cluster:

def load_kube_config(config_file=None, context=None,
                     client_configuration=None,
                     persist_config=True):
    """Loads authentication and cluster information from kube-config file
    and stores them in kubernetes.client.configuration.
    :param config_file: Name of the kube-config file.
    :param context: set the active context. If is set to None, current_context
        from config file will be used.
    :param client_configuration: The kubernetes.client.Configuration to
        set configs to.
    :param persist_config: If True, config file will be updated when changed
        (e.g GCP token refresh).
    """

If I understood the code correctly, you can do somewhat like the following:

from kubernetes import client, config
for file in files:
    config.load_kube_config(config_file=file)
    v1 = client.CoreV1Api()
    response = v1.list_namespace()
    print(response)

EDIT: This is an example that uses the context argument with a single kubeconfig file to iterate over multiple clusters. In the kubernetes docs there is an entry on Merging kubeconfig files. Basically after having a config file with multiple contexts you can load the file with config.load_kube_config(config_file=file) and load contexts with client.load_kube_config(context="context2')

P.S. You don't need to use config.load_kube_config() if you want to use a config file in the default path ('~/.kube/config') or if you set a path in the KUBECONFIG environment variable.

Answer 2

Would you check this example
There you can navigate between multiple contexts and list all pods within all namespaces

Apparently you just need to replace

list_pod_for_all_namespaces()

with

list_namespace()