Load in cluster config by default

Currently we have two method in config module to load config. One from kube config and the other from in-cluster configs. Either add in-cluster config load to load kube config or add a new method (maybe call it load_config or load for short) that tries in-cluster first and then kube-config.

[mbohlool]

from kubernetes import config
config.load_incluster_config()
...

Somebody should add an example for this in examples/ folder.

[jkinkead]

I’d love to see this as part of the API. I implemented a version of this already; I’m happy to put this into a PR if you like:

# Prereqs:
# - import os
# - 'config' is the instance of  kubernetes.client.Configuration being initialized.

# Code:
# Load credentials from the environment.
base_creds_path = '/var/run/secrets/kubernetes.io/serviceaccount'
with open(os.path.join(base_creds_path, 'token')) as token_file:
    config.api_key['authorization'] = 'Bearer {}'.format(token_file.read())
config.ssl_ca_cert = os.path.join(base_creds_path, 'ca.crt')
# Load the "kubernetes" service items.
service_host = os.environ['KUBERNETES_SERVICE_HOST']
service_port = os.environ['KUBERNETES_SERVICE_PORT']
config.host = 'https://{}:{}'.format(service_host, service_port)