[PLAT-4712] #135 NamedTemporaryFile causes issues on Windows platform

Summary: The flush of the named temporary file doesn't seem to cause the secret file to be written out properly on Windows, as the associated bug explains. Instead, we can write to a temporary dir and close the file properly instead

Test Plan: Run on linux and Windows platforms

Reviewers: ysharma-contractor, bgandhi

Reviewed By: bgandhi

Subscribers: yugaware

Differential Revision: https://phabricator.dev.yugabyte.com/D18507

stable/yugabyte/generate_kubeconfig.py

@@ -11,7 +11,7 @@
 import json
 import base64
 import tempfile
-
+import os.path
 
 def run_command(command_args, namespace=None, as_json=True):
     command = ['kubectl']
@@ -66,17 +66,20 @@ def run_command(command_args, namespace=None, as_json=True):
 if not kube_config:
     kube_config = '/tmp/{}.conf'.format(args['service_account'])
 
-with tempfile.NamedTemporaryFile() as ca_crt_file:
-    ca_crt = base64.b64decode(secret_data['data']['ca.crt'])
-    ca_crt_file.write(ca_crt)
-    ca_crt_file.flush()
-    # create kubeconfig entry
-    set_cluster_cmd = ['config', 'set-cluster', cluster_name,
-                       '--kubeconfig={}'.format(kube_config),
-                       '--server={}'.format(endpoint.strip('"')),
-                       '--embed-certs=true',
-                       '--certificate-authority={}'.format(ca_crt_file.name)]
-    run_command(set_cluster_cmd, as_json=False)
+
+tmpdir = tempfile.TemporaryDirectory()
+ca_crt_file_name = os.path.join(tmpdir.name, "ca.crt")
+ca_crt_file = open(ca_crt_file_name, "wb")
+ca_crt_file.write(base64.b64decode(secret_data['data']['ca.crt']))
+ca_crt_file.close()
+
+# create kubeconfig entry
+set_cluster_cmd = ['config', 'set-cluster', cluster_name,
+                    '--kubeconfig={}'.format(kube_config),
+                    '--server={}'.format(endpoint.strip('"')),
+                    '--embed-certs=true',
+                    '--certificate-authority={}'.format(ca_crt_file_name)]
+run_command(set_cluster_cmd, as_json=False)
 
 user_token = base64.b64decode(secret_data['data']['token']).decode('utf-8')
 set_credentials_cmd = ['config', 'set-credentials', context_name,