Add Kubernetes class to track API connection settings

This patch moves get_resources() routine into Kubernetes
class. It's object now holds all needed API connection
properties and tracks it's state to avoid passing these
settings through intermediary functions all the way down
to actual API calling routine.

Additional checks are added in get_resources() to produce
more meaningfull debug info in case of connection failure.

Change-Id: Ia50fa086d22466c0fbed9eb677d2dc52709bef9f
Issue-ID: OOM-1806
Signed-off-by: Bartek Grzybowski <b.grzybowski@partner.samsung.com>

diff --git a/helm_deployment_status.py b/helm_deployment_status.py
index 448263d..f56935e 100755 (executable)
--- a/helm_deployment_status.py
+++ b/helm_deployment_status.py
@@ -33,22 +33,11 @@ from itertools import chain
 import csv
 from requests.packages.urllib3.exceptions import InsecureRequestWarning
 
-
 def add_resource_kind(resources, kind):
     for item in resources:
         item['kind'] = kind
     return resources
 
-def get_resources(server, namespace, api, kind, ssl_verify=False):
-    url = '/'.join([server, api, 'namespaces', namespace, kind])
-    try:
-        req = requests.get(url, verify=ssl_verify)
-    except requests.exceptions.ConnectionError as err:
-        sys.exit('Could not connect to {}'.format(server))
-    json = req.json()
-    # kind is <resource>List in response so [:-4] removes 'List' from value
-    return add_resource_kind(json['items'], json['kind'][:-4])
-
 def pods_by_parent(pods, parent):
     for pod in pods:
         if pod['metadata']['labels']['app'] == parent:
@@ -87,33 +76,29 @@ def analyze_k8s_controllers(resources_data):
 
     return resources
 
-def get_k8s_controllers(namespace, k8s_url):
+def get_k8s_controllers(k8s):
     k8s_controllers = {}
 
-    k8s_controllers['deployments'] = {'data': get_resources(k8s_url, namespace,
+    k8s_controllers['deployments'] = {'data': k8s.get_resources(
         'apis/apps/v1', 'deployments')}
-    k8s_controllers['deployments'].update(analyze_k8s_controllers(k8s_controllers['deployments']['data']))
+    k8s_controllers['deployments'].update(analyze_k8s_controllers(
+        k8s_controllers['deployments']['data']))
 
-    k8s_controllers['statefulsets'] = {'data': get_resources(k8s_url, namespace,
+    k8s_controllers['statefulsets'] = {'data': k8s.get_resources(
         'apis/apps/v1', 'statefulsets')}
-    k8s_controllers['statefulsets'].update(analyze_k8s_controllers(k8s_controllers['statefulsets']['data']))
+    k8s_controllers['statefulsets'].update(analyze_k8s_controllers(
+        k8s_controllers['statefulsets']['data']))
 
-    k8s_controllers['jobs'] = {'data': get_resources(k8s_url, namespace,
+    k8s_controllers['jobs'] = {'data': k8s.get_resources(
         'apis/batch/v1', 'jobs')}
-    k8s_controllers['jobs'].update(analyze_k8s_controllers(k8s_controllers['jobs']['data']))
+    k8s_controllers['jobs'].update(analyze_k8s_controllers(
+        k8s_controllers['jobs']['data']))
 
     not_ready_controllers = chain.from_iterable(
             k8s_controllers[x]['not_ready_list'] for x in k8s_controllers)
 
     return k8s_controllers, list(not_ready_controllers)
 
-def get_k8s_url(kube_config):
-    # TODO: Get login info
-    with open(kube_config) as f:
-        config = yaml.load(f)
-    # TODO: Support cluster by name
-    return config['clusters'][0]['cluster']['server']
-
 def exec_healthcheck(hp_script, namespace):
     try:
         hc = subprocess.check_output(
@@ -123,12 +108,12 @@ def exec_healthcheck(hp_script, namespace):
     except subprocess.CalledProcessError as err:
         return err.returncode, err.output
 
-def check_readiness(k8s_url, namespace, verbosity):
-        k8s_controllers, not_ready_controllers = get_k8s_controllers(namespace, k8s_url)
+def check_readiness(k8s, verbosity):
+        k8s_controllers, not_ready_controllers = get_k8s_controllers(k8s)
 
         # check pods only when it is explicitly wanted (judging readiness by deployment status)
         if verbosity > 1:
-            pods = get_resources(k8s_url, namespace, 'api/v1', 'pods')
+            pods = k8s.get_resources('api/v1', 'pods')
             unready_pods = chain.from_iterable(
                    get_names(not_ready_pods(
                        pods_by_parent(pods, x)))
@@ -139,11 +124,11 @@ def check_readiness(k8s_url, namespace, verbosity):
         print_status(verbosity, k8s_controllers, unready_pods)
         return not not_ready_controllers
 
-def check_in_loop(k8s_url, namespace, max_time, sleep_time, verbosity):
+def check_in_loop(k8s, max_time, sleep_time, verbosity):
     max_end_time = datetime.datetime.now() + datetime.timedelta(minutes=max_time)
     ready = False
     while datetime.datetime.now() < max_end_time:
-        ready = check_readiness(k8s_url, namespace, verbosity)
+        ready = check_readiness(k8s, verbosity)
         if ready:
             return ready
         sleep(sleep_time)
@@ -204,6 +189,43 @@ def parse_args():
 
     return parser.parse_args()
 
+class Kubernetes:
+    '''Class exposing get_resources() routine for connecting to kube API.
+       It keeps all attributes required by that call as an internal
+       object state.'''
+
+    requests.packages.urllib3.disable_warnings(InsecureRequestWarning)
+
+    def __init__(self,args):
+
+        self.config = args.kubeconfig
+        self.url = args.server if args.server is not None else \
+                   self._get_k8s_url()
+        self.namespace = args.namespace
+
+    def get_resources(self, api, kind):
+        '''Performs actual API call'''
+        url = '/'.join([self.url, api, 'namespaces', self.namespace, kind])
+        try:
+            req = requests.get(url, verify=False)
+        except requests.exceptions.ConnectionError as err:
+            sys.exit('Error: Could not connect to {}'.format(self.url))
+        if req.status_code == 200:
+            json = req.json()
+            # kind is <resource>List in response so [:-4] removes 'List' from value
+            return add_resource_kind(json['items'], json['kind'][:-4])
+        elif (req.status_code == 401):
+            sys.exit('Error: Server replied with "401 Unauthorized" while making connection')
+        else:
+            sys.exit("Error: There's been an unspecified issue while making a request to the API")
+
+    def _get_k8s_url(self):
+        # TODO: Get login info
+        with open(self.config) as f:
+            config = yaml.load(f)
+        # TODO: Support cluster by name
+        return config['clusters'][0]['cluster']['server']
+
 def main():
     args = parse_args()
 
@@ -218,16 +240,15 @@ def main():
         except IOError as err:
             sys.exit(err.strerror)
 
-    requests.packages.urllib3.disable_warnings(InsecureRequestWarning)
-    k8s_url = args.server if args.server is not None else get_k8s_url(args.kubeconfig)
+    k8s = Kubernetes(args)
 
     ready = False
     if args.single_run:
-        ready = check_readiness(k8s_url, args.namespace, args.verbosity)
+        ready = check_readiness(k8s, args.verbosity)
     else:
-        if not check_in_loop(k8s_url, args.namespace, args.max_time, args.check_frequency, args.verbosity):
+        if not check_in_loop(k8s, args.max_time, args.check_frequency, args.verbosity):
             # Double-check last 5 minutes and write verbosely in case it is not ready
-            ready = check_readiness(k8s_url, args.namespace, 2)
+            ready = check_readiness(k8s, 2)
 
     if args.health_path is not None:
         try: