I tried following example inside a running pod to list pods

from kubernetes import client, config

 
 def main():
     config.load_incluster_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))
 if __name__ == '__main__':
     main()

It report following error:

ret = v1.list_pod_for_all_namespaces(watch=False)
File "/usr/local/lib/python3.6/site-packages/kubernetes/client/apis/core_v1_api.py", line 13589, in list_pod_for_all_namespaces
(data) = self.list_pod_for_all_namespaces_with_http_info(**kwargs)
File "/usr/local/lib/python3.6/site-packages/kubernetes/client/apis/core_v1_api.py", line 13686, in list_pod_for_all_namespaces_with_http_info
collection_formats=collection_formats)
File "/usr/local/lib/python3.6/site-packages/kubernetes/client/api_client.py", line 321, in call_api
_return_http_data_only, collection_formats, _preload_content, _request_timeout)
File "/usr/local/lib/python3.6/site-packages/kubernetes/client/api_client.py", line 155, in __call_api
_request_timeout=_request_timeout)
File "/usr/local/lib/python3.6/site-packages/kubernetes/client/api_client.py", line 342, in request
headers=headers)
File "/usr/local/lib/python3.6/site-packages/kubernetes/client/rest.py", line 231, in GET
query_params=query_params)
File "/usr/local/lib/python3.6/site-packages/kubernetes/client/rest.py", line 222, in request
raise ApiException(http_resp=r)
kubernetes.client.rest.ApiException: (403)
Reason: Forbidden
HTTP response headers: HTTPHeaderDict({'Content-Type': 'application/json', 'X-Content-Type-Options': 'nosniff', 'Date': 'Wed, 22 Aug 2018 07:56:15 GMT', 'Content-Length': '243'})
HTTP response body: {"kind":"Status","apiVersion":"v1","metadata":{},"status":"Failure","message":"pods is forbidden: User "system:serviceaccount:default:default" cannot list pods at the cluster scope","reason":"Forbidden","details":{"kind":"pods"},"code":403}

I get the configuration setting ,it shows like below:
host:https://172.21.0.1:443
api_key:{"authorization": "bearer <api_key>"}
api_key_prefix:{}
username:
password:
verify_ssl:True
ssl_ca_cert:/var/run/secrets/kubernetes.io/serviceaccount/ca.crt
safe_chars_for_path_param: