Ambassador pod fails in kubernetes for kubernetes api server cluster IP inaccessible - [Errno 113] Host is unreachable',) - kubernetes

Question

Issue with Ambassador deployment starting in Kubernetes:
Kubernetes - v1.13
Ambassador - image: quay.io/datawire/ambassador:0.50.3
Container Runtime - Docker
Cluster networking done used Flannel
The entire set up is done on two Oracle VMs on a single Windows 10 machine.
the network applied is Host-Only with master - 192.168.99.110 and a node - 192.168.99.101.
I am deploying ambassador using kubectl apply -f https://getambassador.io/yaml/ambassador/ambassador-rbac.yaml. After 30 secs when the kubernetes pods starting the Kube watch it goes into a 'CrashLoopBackOff' state. I inspected the logs of the pod and it says below - which at the last sentence states that 10.96.0.1(API Server cluster IP) is unreachable :
" []# kubectl logs ambassador-76f644ddfb-vnj4d
2019-03-06 17:12:13 kubewatch [23 TMainThread] 0.50.3 INFO: kubewatch starting: mode 'cluster-id' ambassador_config_dir '/no/such/path' envoy_config_file '/dev/null' debug 'False' delay '1.0' pid 'None'
2019-03-06 17:12:13 kubewatch [23 TMainThread] 0.50.3 INFO: namespace default, watching all namespaces
2019-03-06 17:12:14,131 WARNING Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7f739506d748>: Failed to establish a new connection: [Errno 113] Host is unreachable',)': /api/v1/namespaces/default
2019-03-06 17:12:14 kubewatch [23 TMainThread] 0.50.3 WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7f739506d748>: Failed to establish a new connection: [Errno 113] Host is unreachable',)': /api/v1/namespaces/default
2019-03-06 17:12:15,136 WARNING Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7f739506d7f0>: Failed to establish a new connection: [Errno 113] Host is unreachable',)': /api/v1/namespaces/default
2019-03-06 17:12:15 kubewatch [23 TMainThread] 0.50.3 WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7f739506d7f0>: Failed to establish a new connection: [Errno 113] Host is unreachable',)': /api/v1/namespaces/default
2019-03-06 17:12:16,140 WARNING Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7f739506d898>: Failed to establish a new connection: [Errno 113] Host is unreachable',)': /api/v1/namespaces/default
2019-03-06 17:12:16 kubewatch [23 TMainThread] 0.50.3 WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7f739506d898>: Failed to establish a new connection: [Errno 113] Host is unreachable',)': /api/v1/namespaces/default
2019-03-06 17:12:17 kubewatch [23 TMainThread] 0.50.3 WARNING: kubewatch failed!
Traceback (most recent call last):
File "/usr/lib/python3.6/site-packages/urllib3/connection.py", line 159, in _new_conn
(self._dns_host, self.port), self.timeout, **extra_kw)
File "/usr/lib/python3.6/site-packages/urllib3/util/connection.py", line 80, in create_connection
raise err
File "/usr/lib/python3.6/site-packages/urllib3/util/connection.py", line 70, in create_connection
sock.connect(sa)
OSError: [Errno 113] Host is unreachable
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/lib/python3.6/site-packages/urllib3/connectionpool.py", line 600, in urlopen
chunked=chunked)
File "/usr/lib/python3.6/site-packages/urllib3/connectionpool.py", line 343, in _make_request
self._validate_conn(conn)
File "/usr/lib/python3.6/site-packages/urllib3/connectionpool.py", line 839, in _validate_conn
conn.connect()
File "/usr/lib/python3.6/site-packages/urllib3/connection.py", line 301, in connect
conn = self._new_conn()
File "/usr/lib/python3.6/site-packages/urllib3/connection.py", line 168, in _new_conn
self, "Failed to establish a new connection: %s" % e)
urllib3.exceptions.NewConnectionError: <urllib3.connection.VerifiedHTTPSConnection object at 0x7f739506d9b0>: Failed to establish a new connection: [Errno 113] Host is unreachable
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/ambassador/kubewatch.py", line 527, in <module>
main()
File "/usr/lib/python3.6/site-packages/click/core.py", line 764, in __call__
return self.main(*args, **kwargs)
File "/usr/lib/python3.6/site-packages/click/core.py", line 717, in main
rv = self.invoke(ctx)
File "/usr/lib/python3.6/site-packages/click/core.py", line 956, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/usr/lib/python3.6/site-packages/click/core.py", line 555, in invoke
return callback(*args, **kwargs)
File "/ambassador/kubewatch.py", line 518, in main
watcher.run(id_only=True)
File "/ambassador/kubewatch.py", line 342, in run
self.get_cluster_id(v1)
File "/ambassador/kubewatch.py", line 407, in get_cluster_id
ret = v1.read_namespace(wanted)
File "/usr/lib/python3.6/site-packages/kubernetes/client/apis/core_v1_api.py", line 17572, in read_namespace
(data) = self.read_namespace_with_http_info(name, **kwargs)
File "/usr/lib/python3.6/site-packages/kubernetes/client/apis/core_v1_api.py", line 17657, in read_namespace_with_http_info
collection_formats=collection_formats)
File "/usr/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/lib/python3.6/site-packages/kubernetes/client/api_client.py", line 155, in __call_api
_request_timeout=_request_timeout)
File "/usr/lib/python3.6/site-packages/kubernetes/client/api_client.py", line 342, in request
headers=headers)
File "/usr/lib/python3.6/site-packages/kubernetes/client/rest.py", line 231, in GET
query_params=query_params)
File "/usr/lib/python3.6/site-packages/kubernetes/client/rest.py", line 205, in request
headers=headers)
File "/usr/lib/python3.6/site-packages/urllib3/request.py", line 68, in request
**urlopen_kw)
File "/usr/lib/python3.6/site-packages/urllib3/request.py", line 89, in request_encode_url
return self.urlopen(method, url, **extra_kw)
File "/usr/lib/python3.6/site-packages/urllib3/poolmanager.py", line 323, in urlopen
response = conn.urlopen(method, u.request_uri, **kw)
File "/usr/lib/python3.6/site-packages/urllib3/connectionpool.py", line 667, in urlopen
**response_kw)
File "/usr/lib/python3.6/site-packages/urllib3/connectionpool.py", line 667, in urlopen
**response_kw)
File "/usr/lib/python3.6/site-packages/urllib3/connectionpool.py", line 667, in urlopen
**response_kw)
File "/usr/lib/python3.6/site-packages/urllib3/connectionpool.py", line 638, in urlopen
_stacktrace=sys.exc_info()[2])
File "/usr/lib/python3.6/site-packages/urllib3/util/retry.py", line 398, in increment
raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPSConnectionPool(host='10.96.0.1', port=443): Max retries exceeded with url: /api/v1/namespaces/default (Caused by NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x7f739506d9b0>: Failed to establish a new connection: [Errno 113] Host is unreachable',))
AMBASSADOR: kubewatch cluster-id exited with status 1
AMBASSADOR: shutting down (1)"

Answer 1

An update. I have disabled firewalld service in both master and node and the issue is solved now. I think the root cause was due to PODs in the node were not able to access the kube-dns on the master due to firewall restrictions.