Network policy not working using pods label selector

suser

Hello!

During ex 6.6 I am not able get my network policy to block all ingress and egress traffic using pod selector by label, after creation and re-creation of the deployment I am still able to access nginx web page when I expected to get any traffic denied. Any help is greatly appreciated:

kubectl describe networkpolicies netblock
Name: netblock
Namespace: default
Created on: 2020-04-28 01:26:37 +0000 UTC
Labels:
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"networking.k8s.io/v1","kind":"NetworkPolicy","metadata":{"annotations":{},"name":"netblock","namespace":"default"},"spec":{...
Spec:
PodSelector: app=nserver
Allowing ingress traffic:
(Selected pods are isolated for ingress connectivity)
Allowing egress traffic:
(Selected pods are isolated for egress connectivity)
Policy Types: Ingress, Egress

network policy yaml:
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
name: netblock
namespace: default
spec:
podSelector:
matchLabels:
app: nserver
policyTypes:
- Ingress
- Egress

kubectl describe pod ndeploy-76dcd7ccd8-jmjp4 | grep Labels
Labels: app=nserver

kubectl describe pod ndeploy-76dcd7ccd8-jmjp4
Name: ndeploy-76dcd7ccd8-jmjp4
Namespace: default
Priority: 0
Node: kw1/10.1.10.31
Start Time: Tue, 28 Apr 2020 01:47:11 +0000
Labels: app=nserver
pod-template-hash=76dcd7ccd8
type=nserver
Annotations: cni.projectcalico.org/podIP: 192.168.159.115/32
Status: Running
IP: 192.168.159.115
IPs:
IP: 192.168.159.115
Controlled By: ReplicaSet/ndeploy-76dcd7ccd8
Containers:
nginx:
Container ID: docker://f4924d52f1e021a9304795ee0b9e4078cb4fee81f20a04cd74ec6a37b1be8262
Image: nginx:1.14.2
Image ID: docker-pullable://nginx@sha256:f7988fb6c02e0ce69257d9bd9cf37ae20a60f1df7563c3a2a6abe24160306b8d
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Tue, 28 Apr 2020 01:47:13 +0000
Ready: True
Restart Count: 0
Environment:
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-zqbsw (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
default-token-zqbsw:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-zqbsw
Optional: false
QoS Class: BestEffort
Node-Selectors:
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 7m5s default-scheduler Successfully assigned default/ndeploy-76dcd7ccd8-jmjp4 to kw1
Normal Pulled 7m4s kubelet, kw1 Container image "nginx:1.14.2" already present on machine
Normal Created 7m4s kubelet, kw1 Created container nginx

Stefan

chrispokorni

Hi Stefan,

I would recommend reading up on the network policy documentation. In the introductory sections, you will find explained how the policy behaves once you introduce selectors. It may be the opposite of what you would expect

https://kubernetes.io/docs/concepts/services-networking/network-policies/

Regards,
-Chris

chrispokorni

Hi Stefan,

You can take a look at the default policy examples available in the official documentation:

https://kubernetes.io/docs/concepts/services-networking/network-policies/#default-policies

You may notice that default policies do not include any selectors.

Regards,
-Chris

suser

Chris,
I will be very thankful to learn how to use the NetworkPolicy spec.podselectors to filter pods for which a network policy applies for.

Stefan

suser

Thank you very much Chris, I read the third time and I realized that my new policy was only adding to the one previously created; I deleted the old one and now the new policy is working for my selected pods as expected.

Stefan