Exploring Path-Based and Header-Based Routing Solutions in Knative

xiaoqing included in category knative

2022-01-15 2022-01-15 2989 words 15 minutes

Contents

Currently, in Knative version 1.1.0, traffic routing is primarily based on domain names.

However, in many use cases:

Services often have fixed external domain names, and there may be multiple of them.
Services are typically organized under specific paths within a domain, meaning one domain consists of multiple services.
Grey releases are based on multiple header values with and and or relationships.

Let’s discuss how to address these requirements.

1 Domain Binding

Apart from using Knative’s default domain, Knative provides domainMapping to bind additional domains.

Create a Knative service named example-nginx, and it will generate the domain example-nginx.default.example.com.

Then, you can bind another domain, such as out.com, to example-nginx.

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apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  annotations:
    serving.knative.dev/creator: admin
    serving.knative.dev/lastModifier: admin
  name: example-nginx
  namespace: default
spec:
  template:
    metadata:
      creationTimestamp: null
    spec:
      containerConcurrency: 0
      containers:
      - image: xxx.com/k8s/test-nginx:v1.21
        name: nginx
        ports:
        - containerPort: 80
          protocol: TCP
        readinessProbe:
          successThreshold: 1
          tcpSocket:
            port: 0
        resources: {}
      enableServiceLinks: false
      timeoutSeconds: 300
  traffic:
  - latestRevision: true
    percent: 50
  - latestRevision: false
    percent: 50
    revisionName: example-nginx-00006
    tag: canary
status:
  address:
    url: http://example-nginx.default.svc.cluster.local
  conditions:
  - lastTransitionTime: "2022-01-12T13:07:07Z"
    status: "True"
    type: ConfigurationsReady
  - lastTransitionTime: "2022-01-12T13:08:15Z"
    status: "True"
    type: Ready
  - lastTransitionTime: "2022-01-12T13:08:15Z"
    status: "True"
    type: RoutesReady
  latestCreatedRevisionName: example-nginx-00006
  latestReadyRevisionName: example-nginx-00006
  observedGeneration: 13
  traffic:
  - latestRevision: true
    percent: 50
    revisionName: example-nginx-00006
  - latestRevision: false
    percent: 50
    revisionName: example-nginx-00006
    tag: canary
    url: http://canary-example-nginx.default.example.com
  url: http://example-nginx.default.example.com

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apiVersion: serving.knative.dev/v1beta1
kind: DomainMapping
metadata:
  name: out.com
  namespace: default
spec:
  ref:
    name: example-nginx
    namespace: default
    kind: Service
    apiVersion: serving.knative.dev/v1

1.1 Underlying implementation principles

Knative services and DomainMappings both generate Knative Ingress resources. Knative utilizes Ingress to abstract traffic routing, while Net Istio uses Istio to implement traffic routing. The Net Istio component translates Knative’s Ingress objects into Istio’s VirtualService objects.

Therefore, domain binding effectively involves working with Knative Ingress and Istio VirtualService.

The hierarchy of these resources is as follows: Knative Service -> Knative Route -> Knative Ingress -> VirtualService.

In the context of example-nginx, it corresponds to Ingress resources and VirtualService resources."

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apiVersion: networking.internal.knative.dev/v1alpha1
kind: Ingress
metadata:
  annotations:
    networking.internal.knative.dev/rollout: '{"configurations":[{"configurationName":"example-nginx","percent":100,"revisions":[{"revisionName":"example-nginx-00006","percent":100}],"stepParams":{}}]}'
    networking.knative.dev/ingress.class: istio.ingress.networking.knative.dev
    serving.knative.dev/creator: admin
    serving.knative.dev/lastModifier: admin
  creationTimestamp: "2022-01-11T06:21:28Z"
  finalizers:
  - ingresses.networking.internal.knative.dev
  generation: 8
  labels:
    serving.knative.dev/route: example-nginx
    serving.knative.dev/routeNamespace: default
    serving.knative.dev/service: example-nginx
  name: example-nginx
  namespace: default
spec:
  httpOption: Enabled
  rules:
  - hosts:
    - example-nginx.default
    - example-nginx.default.svc
    - example-nginx.default.svc.cluster.local
    http:
      paths:
      - headers:
          Knative-Serving-Tag:
            exact: canary
        splits:
        - appendHeaders:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
          percent: 100
          serviceName: example-nginx-00006
          serviceNamespace: default
          servicePort: 80
      - appendHeaders:
          Knative-Serving-Default-Route: "true"
        splits:
        - appendHeaders:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
          percent: 100
          serviceName: example-nginx-00006
          serviceNamespace: default
          servicePort: 80
    visibility: ClusterLocal
  - hosts:
    - example-nginx.default.example.com
    http:
      paths:
      - headers:
          Knative-Serving-Tag:
            exact: canary
        splits:
        - appendHeaders:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
          percent: 100
          serviceName: example-nginx-00006
          serviceNamespace: default
          servicePort: 80
      - appendHeaders:
          Knative-Serving-Default-Route: "true"
        splits:
        - appendHeaders:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
          percent: 100
          serviceName: example-nginx-00006
          serviceNamespace: default
          servicePort: 80
    visibility: ExternalIP
  - hosts:
    - canary-example-nginx.default
    - canary-example-nginx.default.svc
    - canary-example-nginx.default.svc.cluster.local
    http:
      paths:
      - appendHeaders:
          Knative-Serving-Tag: canary
        splits:
        - appendHeaders:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
          percent: 100
          serviceName: example-nginx-00006
          serviceNamespace: default
          servicePort: 80
    visibility: ClusterLocal
  - hosts:
    - canary-example-nginx.default.example.com
    http:
      paths:
      - appendHeaders:
          Knative-Serving-Tag: canary
        splits:
        - appendHeaders:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
          percent: 100
          serviceName: example-nginx-00006
          serviceNamespace: default
          servicePort: 80
    visibility: ExternalIP
status:
  conditions:
  - lastTransitionTime: "2022-01-12T13:08:15Z"
    status: "True"
    type: LoadBalancerReady
  - lastTransitionTime: "2022-01-11T06:21:28Z"
    status: "True"
    type: NetworkConfigured
  - lastTransitionTime: "2022-01-12T13:08:15Z"
    status: "True"
    type: Ready
  observedGeneration: 8
  privateLoadBalancer:
    ingress:
    - domainInternal: knative-local-gateway.istio-system.svc.cluster.local
  publicLoadBalancer:
    ingress:
    - domainInternal: istio-ingressgateway.istio-system.svc.cluster.local

---
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  annotations:
    networking.internal.knative.dev/rollout: '{"configurations":[{"configurationName":"example-nginx","percent":100,"revisions":[{"revisionName":"example-nginx-00006","percent":100}],"stepParams":{}}]}'
    networking.knative.dev/ingress.class: istio.ingress.networking.knative.dev
    serving.knative.dev/creator: admin
    serving.knative.dev/lastModifier: admin
  creationTimestamp: "2022-01-11T06:21:28Z"
  generation: 32
  labels:
    networking.internal.knative.dev/ingress: example-nginx
    serving.knative.dev/route: example-nginx
    serving.knative.dev/routeNamespace: default
  name: example-nginx-ingress
  namespace: default
  ownerReferences:
  - apiVersion: networking.internal.knative.dev/v1alpha1
    blockOwnerDeletion: true
    controller: true
    kind: Ingress
    name: example-nginx
    uid: 94592245-c9ef-4321-88a5-a7d3cd57b383
spec:
  gateways:
  - knative/knative-ingress-gateway
  - knative/knative-local-gateway
  hosts:
  - canary-example-nginx.default
  - canary-example-nginx.default.example.com
  - canary-example-nginx.default.svc
  - canary-example-nginx.default.svc.cluster.local
  - example-nginx.default
  - example-nginx.default.example.com
  - example-nginx.default.svc
  - example-nginx.default.svc.cluster.local
  http:
  - headers:
      request:
        set:
          K-Network-Hash: 1d94c6d2b2727715d4e9ef39ef170cfe3863d7bf72b0f373841b77e47be1c3cc
    match:
    - authority:
        prefix: example-nginx.default
      gateways:
      - knative/knative-local-gateway
      headers:
        K-Network-Hash:
          exact: override
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100
  - headers:
      request:
        set:
          K-Network-Hash: 1d94c6d2b2727715d4e9ef39ef170cfe3863d7bf72b0f373841b77e47be1c3cc
          Knative-Serving-Default-Route: "true"
    match:
    - authority:
        prefix: example-nginx.default
      gateways:
      - knative/knative-local-gateway
      headers:
        K-Network-Hash:
          exact: override
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100
  - match:
    - authority:
        prefix: example-nginx.default
      gateways:
      - knative/knative-local-gateway
      headers:
        Knative-Serving-Tag:
          exact: canary
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100
  - headers:
      request:
        set:
          Knative-Serving-Default-Route: "true"
    match:
    - authority:
        prefix: example-nginx.default
      gateways:
      - knative/knative-local-gateway
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100
  - headers:
      request:
        set:
          K-Network-Hash: 1d94c6d2b2727715d4e9ef39ef170cfe3863d7bf72b0f373841b77e47be1c3cc
    match:
    - authority:
        prefix: example-nginx.default.example.com
      gateways:
      - knative/knative-ingress-gateway
      headers:
        K-Network-Hash:
          exact: override
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100
  - headers:
      request:
        set:
          K-Network-Hash: 1d94c6d2b2727715d4e9ef39ef170cfe3863d7bf72b0f373841b77e47be1c3cc
          Knative-Serving-Default-Route: "true"
    match:
    - authority:
        prefix: example-nginx.default.example.com
      gateways:
      - knative/knative-ingress-gateway
      headers:
        K-Network-Hash:
          exact: override
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100
  - match:
    - authority:
        prefix: example-nginx.default.example.com
      gateways:
      - knative/knative-ingress-gateway
      headers:
        Knative-Serving-Tag:
          exact: canary
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100
  - headers:
      request:
        set:
          Knative-Serving-Default-Route: "true"
    match:
    - authority:
        prefix: example-nginx.default.example.com
      gateways:
      - knative/knative-ingress-gateway
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100
  - headers:
      request:
        set:
          K-Network-Hash: 1d94c6d2b2727715d4e9ef39ef170cfe3863d7bf72b0f373841b77e47be1c3cc
          Knative-Serving-Tag: canary
    match:
    - authority:
        prefix: canary-example-nginx.default
      gateways:
      - knative/knative-local-gateway
      headers:
        K-Network-Hash:
          exact: override
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100
  - headers:
      request:
        set:
          Knative-Serving-Tag: canary
    match:
    - authority:
        prefix: canary-example-nginx.default
      gateways:
      - knative/knative-local-gateway
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100
  - headers:
      request:
        set:
          K-Network-Hash: 1d94c6d2b2727715d4e9ef39ef170cfe3863d7bf72b0f373841b77e47be1c3cc
          Knative-Serving-Tag: canary
    match:
    - authority:
        prefix: canary-example-nginx.default.example.com
      gateways:
      - knative/knative-ingress-gateway
      headers:
        K-Network-Hash:
          exact: override
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100
  - headers:
      request:
        set:
          Knative-Serving-Tag: canary
    match:
    - authority:
        prefix: canary-example-nginx.default.example.com
      gateways:
      - knative/knative-ingress-gateway
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100

The ingress and virtualservice corresponding to DomainMapping

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apiVersion: networking.internal.knative.dev/v1alpha1
kind: Ingress
metadata:
  annotations:
    networking.knative.dev/ingress.class: istio.ingress.networking.knative.dev
    serving.knative.dev/creator: admin
    serving.knative.dev/lastModifier: admin
  creationTimestamp: "2022-01-12T06:06:48Z"
  finalizers:
  - ingresses.networking.internal.knative.dev
  generation: 1
  labels:
    serving.knative.dev/domainMappingNamespace: default
    serving.knative.dev/domainMappingUID: 111ff4ba-a357-4861-a089-5c35b8760770
  name: out.com
  namespace: default
  ownerReferences:
  - apiVersion: serving.knative.dev/v1alpha1
    blockOwnerDeletion: true
    controller: true
    kind: DomainMapping
    name: out.com
    uid: 111ff4ba-a357-4861-a089-5c35b8760770
  resourceVersion: "393747308"
  uid: 81fa388f-1211-4d82-9cc4-46c4e38c79e6
spec:
  httpOption: Enabled
  rules:
  - hosts:
    - out.com
    http:
      paths:
      - rewriteHost: example-nginx.default.svc.cluster.local
        splits:
        - appendHeaders:
            K-Original-Host: out.com
          percent: 100
          serviceName: example-nginx
          serviceNamespace: default
          servicePort: 80
    visibility: ExternalIP
status:
  conditions:
  - lastTransitionTime: "2022-01-12T06:06:49Z"
    status: "True"
    type: LoadBalancerReady
  - lastTransitionTime: "2022-01-12T06:06:48Z"
    status: "True"
    type: NetworkConfigured
  - lastTransitionTime: "2022-01-12T06:06:49Z"
    status: "True"
    type: Ready
  observedGeneration: 1
  privateLoadBalancer:
    ingress:
    - domainInternal: knative-local-gateway.istio-system.svc.cluster.local
  publicLoadBalancer:
    ingress:
    - domainInternal: istio-ingressgateway.istio-system.svc.cluster.local
---
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  annotations:
    networking.knative.dev/ingress.class: istio.ingress.networking.knative.dev
    serving.knative.dev/creator: admin
    serving.knative.dev/lastModifier: admin
  creationTimestamp: "2022-01-12T06:06:48Z"
  generation: 1
  labels:
    networking.internal.knative.dev/ingress: out.com
  name: out.com-ingress
  namespace: default
  ownerReferences:
  - apiVersion: networking.internal.knative.dev/v1alpha1
    blockOwnerDeletion: true
    controller: true
    kind: Ingress
    name: out.com
    uid: 81fa388f-1211-4d82-9cc4-46c4e38c79e6
  resourceVersion: "393747283"

  uid: 61148c5f-5541-4b35-90d8-1c90c6601c66
spec:
  gateways:
  - knative/knative-ingress-gateway
  hosts:
  - out.com
  http:
  - headers:
      request:
        set:
          K-Network-Hash: b5c1fc426bf11303c158115fde3a06530e29d7aac00c60d6f469b6a0948ae362
    match:
    - authority:
        prefix: out.com
      gateways:
      - knative/knative-ingress-gateway
      headers:
        K-Network-Hash:
          exact: override
    retries: {}
    rewrite:
      authority: example-nginx.default.svc.cluster.local
    route:
    - destination:
        host: example-nginx.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            K-Original-Host: out.com
      weight: 100
  - match:
    - authority:
        prefix: out.com
      gateways:
      - knative/knative-ingress-gateway
    retries: {}
    rewrite:
      authority: example-nginx.default.svc.cluster.local
    route:
    - destination:
        host: example-nginx.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            K-Original-Host: out.com
      weight: 100

2 Forwarding Based on Paths

If a domain is composed of multiple services, you’ll need to deploy multiple Knative services. A Knative service will generate a domain, so for one external service domain, there will correspond to multiple Knative domains.

How can you achieve a single domain for external access with path-based forwarding?

You can use the official example method and directly manipulate VirtualService.
Currently, Knative Ingress supports forwarding based on headers and paths. You can directly manipulate Knative Ingress to achieve this.

Here, let’s discuss how to use Knative Ingress to implement it:

Create a Knative Ingress configuration with the domain as “url.com” and the path as “/url-1”.

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apiVersion: networking.internal.knative.dev/v1alpha1
kind: Ingress
metadata:
  annotations:
    networking.knative.dev/ingress.class: istio.ingress.networking.knative.dev
  name: url-1
spec:
  httpOption: Enabled
  rules:
  - hosts:
    - url.com
    http:
      paths:
      - headers:
          version:
            exact: canary
          abc:
            exact: abc
        path: "/url-1"
        splits:
        - appendHeaders:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
          percent: 100
          serviceName: example-nginx-00006
          serviceNamespace: default
          servicePort: 80
    visibility: ExternalIP

the generated virtualservice

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apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  annotations:
    networking.knative.dev/ingress.class: istio.ingress.networking.knative.dev
  creationTimestamp: "2022-01-15T10:35:46Z"
  generation: 1
  labels:
    networking.internal.knative.dev/ingress: url-1
  name: url-1-ingress
  namespace: default
  ownerReferences:
  - apiVersion: networking.internal.knative.dev/v1alpha1
    blockOwnerDeletion: true
    controller: true
    kind: Ingress
    name: url-1
    uid: 0a1f2e17-cacf-4656-8b75-8f3df9296372
  resourceVersion: "399816649"
  selfLink: /apis/networking.istio.io/v1beta1/namespaces/default/virtualservices/url-1-ingress
  uid: 58d750d0-150a-4baa-8100-030e7c8bd40c
spec:
  gateways:
  - knative/knative-ingress-gateway
  hosts:
  - url.com
  http:
  - headers:
      request:
        set:
          K-Network-Hash: 1eb7ef10f7c01124526d9c594a088852b7146b167a1641af4b62eb3278e2ff59
    match:
    - authority:
        prefix: url.com
      gateways:
      - knative/knative-ingress-gateway
      headers:
        K-Network-Hash:
          exact: override
      uri:
        prefix: /url-1
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100
  - match:
    - authority:
        prefix: url.com
      gateways:
      - knative/knative-ingress-gateway
      headers:
        version:
          exact: canary
      uri:
        prefix: /url-1
    retries: {}
    route:
    - destination:
        host: example-nginx-00006.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: example-nginx-00006
      weight: 100

3 Implementing Header-Based Routing with Multiple Headers for Canary Deployment

How can you achieve routing based on multiple headers?

You can directly manipulate VirtualService.
You can use Knative Ingress to implement this.

Here, we’ll focus on using Knative Ingress to achieve it.

Currently, Knative Ingress supports precise header matching and supports both “OR” and “AND” relationships between headers.

In the example below, version:canary and abc:abc have an “AND” relationship.

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apiVersion: networking.internal.knative.dev/v1alpha1
kind: Ingress
.....
spec:
  httpOption: Enabled
  rules:
  - hosts:
    - url.com
    http:
      paths:
      - headers:
          version:
            exact: canary
          abc:
            exact: abc
        path: "/url-1"

In the example below, version:canary and abc:abc have an “OR” relationship.

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apiVersion: networking.internal.knative.dev/v1alpha1
kind: Ingress
.....
spec:
  httpOption: Enabled
  rules:
  - hosts:
    - url.com
    http:
      paths:
      - headers:
          version:
            exact: canary
        path: "/url-1"
      - headers:
          abc:
            exact: abc
        path: "/url-1"

3.1 Issues in net-istio Implementation

While Knative Ingress supports path-based routing and header-based routing, there are several issues in the net-istio implementation:

In the example of path-based routing above, the defined headers version:canary and abc:abc are in an “AND” relationship, but the resulting VirtualService only contains one header matching condition. Relevant issue link: https://github.com/knative-sandbox/net-istio/issues/847

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  - match:
    - authority:
        prefix: url.com
      gateways:
      - knative/knative-ingress-gateway
      headers:
        version:
          exact: canary
      uri:
        prefix: /url-1

net-istio performs probe detection on newly created ingress resources. It does this by accessing the Istio Ingress Gateway at url.com:80/healthz. If it returns a 200 status (or returns 200 and the K-Network-Hash header in the response matches the spec hash value of the ingress), it updates the condition in the ingress status to true.

However, the generated VirtualService rules do not include a path for /healthz, causing the probe to return a 404 status. While this does not affect VirtualService generation, the ingress status remains in an “unknown” state. Relevant issue link: https://github.com/knative-sandbox/net-istio/issues/848

Currently, you can set up an EnvoyFilter rule to match the /healthz path of url.com and return a direct 200 status to resolve this issue.

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status:
  conditions:
  - lastTransitionTime: "2022-01-15T10:35:46Z"
    message: Waiting for load balancer to be ready
    reason: Uninitialized
    status: Unknown
    type: LoadBalancerReady
  - lastTransitionTime: "2022-01-15T10:35:46Z"
    status: "True"
    type: NetworkConfigured
  - lastTransitionTime: "2022-01-15T10:35:46Z"
    message: Waiting for load balancer to be ready
    reason: Uninitialized
    status: Unknown
    type: Ready
  observedGeneration: 1

Currently, you can set up an EnvoyFilter rule to match the /healthz path of url.com and return a direct 200 status to resolve this issue.

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apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: net-istio-probe
  namespace: namespace-of-sidecar
spec:
  workloadSelector:
    labels:
      app: istio-ingressgateway
  configPatches:
  - applyTo: HTTP_ROUTE
    match:
      context: GATEWAY
      routeConfiguration:
        vhost:
          name: url.com:80
    patch:
      operation: INSERT_FIRST
      value:
        name: direct-healthz-response
        match:
          prefix: /healthz
        directResponse:
          body:
            inlineString: 'ok'
          status: 200

4 Community Progress

The community is proposing the definition of a Dispatcher to achieve path and header routing forwarding, with the underlying design based on ingress and VirtualService.

Design Prototype: Use DomainMapping to bind domains and Dispatcher, configure path and header routing forwarding in Dispatcher, and finally generate Knative Ingress.

5 Conclusion

Knative’s Ingress has already implemented routing based on routing rules, but Knative Service does not yet support it. So, based on the current Knative version 1.1.0, there are two approaches to binding domains and implementing path and header forwarding:

Directly manipulate VirtualService.

Pros: Supports not only path and header matching but also other features like path regex matching and domain regex matching.

Cons: Only supports Istio.
Operate Knative Ingress.

Pros: Uses Knative-native resources, follows community standards, and has good compatibility. It can work with any implementation.

Cons: Only supports exact matching, lacks some advanced features. However, you can extend functionality similar to Kubernetes Ingress resources using labels or annotations.