Access Policy¶

Info

Network policies and Istio authorization is only applied in GCP clusters.

However, inbound rules for authorization in the context of TokenX or Azure AD apply to all clusters.

Access Policy¶

Access policies express which applications and services you are able to communicate with, both inbound and outbound. The default policy is to deny all incoming and outgoing traffic for your application, meaning you must be conscious of which services/application you consume, and who your consumers are.

Warning

The Istio access policies only apply when communicating interally within the cluster with service discovery.

Outbound requests to ingresses are regarded as external hosts, even if these ingresses exist in the same cluster.

Analogously, inbound access policies are thus not enforced for requests coming through exposed ingresses.

Inbound rules¶

Inbound rules specifies what other applications in the same cluster your application receives traffic from.

Receive requests from other app in the same namespace¶

For app app-a to be able to receive incoming requests from app-b in the same cluster and the same namespace, this specification is needed for app-a:

apiVersion: "nais.io/v1alpha1"
kind: "Application"
metadata:
  name: app-a
...
spec:
  ...
  accessPolicy:
    inbound:
      rules:
        - application: app-b

Receive requests from other app in the another namespace¶

For app app-a to be able to receive incoming requests from app-b in the same cluster but another namespace (othernamespace), this specification is needed for app-a:

apiVersion: "nais.io/v1alpha1"
kind: "Application"
metadata:
  name: app-a
...
spec:
  ...
  accessPolicy:
    inbound:
      rules:
        - application: app-b
          namespace: othernamespace

Outbound rules¶

Inbound rules specifies what other applications your application receives traffic from. spec.accessPolicy.outbound.rules specifies which applications in the same cluster to open for. To open for external applications, use the field spec.accessPolicy.outbound.external.

Send requests to other app in the same namespace¶

For app app-a to be able to send requests to app-b in the same cluster and the same namespace, this specification is needed for app-a:

apiVersion: "nais.io/v1alpha1"
kind: "Application"
metadata:
  name: app-a
...
spec:
  ...
  accessPolicy:
    outbound:
      rules:
        - application: app-b

Send requests to other app in the another namespace¶

For app app-a to be able to send requests requests to app-b in the same cluster but in another namespace (othernamespace), this specification is needed for app-a:

apiVersion: "nais.io/v1alpha1"
kind: "Application"
metadata:
  name: app-a
...
spec:
  ...
  accessPolicy:
    outbound:
      rules:
        - application: app-b
          namespace: othernamespace

External services¶

In order to send requests to services outside of the cluster, external.host is needed:

apiVersion: "nais.io/v1alpha1"
kind: "Application"
metadata:
  name: app-a
...
spec:
  ...
  accessPolicy:
    outbound:
      external: 
        - host: www.external-application.com

Global Service Entries

There are some services that are automatically added to the mesh in dev-gcp and prod-gcp

Advanced: Resources created by Naiserator¶

The previous application manifest examples will create both Kubernetes Network Policies and Istio resources.

Kubernetes Network Policy¶

Default policy

Every app created will have this default network policy that allows traffic from Istio pilot and mixer, as well as kube-dns. This policy will be created for every app, also those who don't have any access policies specified.

apiVersion: extensions/v1beta1
kind: NetworkPolicy
metadata:
  labels:
    app: appname
    team: teamname
  name: appname
  namespace: teamname
spec:
  egress:
  - to:
    - namespaceSelector:
        matchLabels:
          name: istio-system
      podSelector:
        matchLabels:
          istio: pilot
    - namespaceSelector:
        matchLabels:
          name: istio-system
      podSelector:
        matchLabels:
          istio: mixer
    - namespaceSelector: {}
      podSelector:
        matchLabels:
          k8s-app: kube-dns
    - ipBlock:
        cidr: 0.0.0.0/0
        except:
        - 10.0.0.0/8
        - 172.16.0.0/12
        - 192.168.0.0/16
  podSelector:
    matchLabels:
      app: appname
  policyTypes:
  - Egress

Kubernetes network policies

The applications specified in spec.accessPolicy.inbound.rules and spec.accessPolicy.outbound.rules will append these fields to the default Network Policy:

apiVersion: extensions/v1beta1
kind: NetworkPolicy
...
spec:
  egress:
  - to:
    ...
    - namespaceSelector:
        matchLabels:
          name: othernamespace
      podSelector:
        matchLabels:
          app: app-b
    - podSelector:
        matchLabels:
          app: app-b  
  - from:
    - namespaceSelector:
        matchLabels:
          name: othernamespace
      podSelector:
        matchLabels:
          app: app-b
    - podSelector:
        matchLabels:
          app: app-b    
  podSelector:
    matchLabels:
      app: appname
  policyTypes:
  - Egress
  - Ingress

Info

Note that for namespace match labels to work, the namespaces must be labeled with name: namespacename.

kube-system should be labeled accordingly for the default rule that allows traffic to kube-dns, but in GCP, the label is removed by some job in regular intervals...

Istio Resources¶

The policies from spec.accessPolicy will in addition create these Istio-resources:

ServiceRole and ServiceRoleBinding

For Istio to allow request from app-b in the same namespace and in othernamespace, these resources will be created:

apiVersion: rbac.istio.io/v1alpha1
kind: ServiceRole
metadata:
  labels:
    app: app-a
    team: my-team 
  name: app-a
  namespace: my-team
spec:
  rules:
  - methods:
    - '*'
    paths:
    - '*'
    services:
    - app-a.my-team.svc.cluster.local

apiVersion: rbac.istio.io/v1alpha1
kind: ServiceRoleBinding
metadata:
  labels:
    app: app-a
    team: my-team
  name: app-a
  namespace: my-team
spec:
  roleRef:
    kind: ServiceRole
    name: app-a
  subjects:
  - user: cluster.local/ns/my-team/sa/app-b
  - user: cluster.local/ns/othernamespace/sa/app-b

ServiceEntry

spec.accessRules.outbound.external will create ServiceEntry:

apiVersion: networking.istio.io/v1alpha3
kind: ServiceEntry
metadata:
  labels:
    app: app-a
    team: my-team
  name: app-a
  namespace: my-team
spec:
  hosts:
  - www.external-application.com
  location: MESH_EXTERNAL
  ports:
  - name: https
    number: 443
    protocol: HTTPS
  resolution: DNS

VirtualService

In the cloud spec.ingresses will create VirtualService instead of Ingress objects:

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  labels:
    app: app-a
    team: my-team
  name: app-a-app-a-dev-gcp-nais-io
  namespace: my-team
spec:
  gateways:
  - istio-system/ingress-gateway-nais-io
  hosts:
  - my-app.dev-gcp.nais.io
  http:
  - route:
    - destination:
        host: app-a
        port:
          number: 80
        subset: ""
      weight: 100