6. Istio Gateway

Why we need Istio Gateway?

• Because the proxies run after a container makes a request, so if users access a specific pod directly, you can’t use routing.
  • Without Ingress Gateway:

  

    - With Ingress Gateway (Edge Proxy):
  

  web -> Istion Gateway (pod -> proxy) -> proxy A (80%) -> pod A -> proxy B (20%) -> pod B ```

• Type:
  • Default: LoadBalancer
• Configuring ingress using an Istio gateway
• Note: You can restirct the request to specific hosts by adding hosts in spec:

    apiVersion: networking.istio.io/v1alhpa3
    kind: Gateway
    metadata:
      name: ingress-gateway-configuration // default isiot gateway
    spec:
      selector:
        istio: ingressgateway
      servers:
      - port:
          number: 80
          name: http
          protocol: HTTP
        hosts:
        - test.example.com
  

  Advanced

• Prefixing Routing
  • HttpRequestMatch
    • uri:
      • exact
      • prefix
      • regex
        • example: ```yaml spec:
          • match:
            • uri: # if prefix: “/test1”
            • uri: # or prefix: “/test2” route: # then
            • destination: host: app1 subset: test
          • match:
            • uri: prefix: “/” route:
            • destination: host: app2 subset: origin ```
    • Headers
      • exact
        • example: ```yaml http:
          • match:
            • headers hederOne: exact: test1 route:
            • destination: host: test1-myweb subset: test1
          • route: # catch all
            • destination: host: default-myweb subset: default ```
      • prefix
      • regex
    • Reference: HTTPMatchRequest
• Subdomain Routing

    apiVersion: networing.istio.io/v1alpha3
    kind: Gateway
    metadata:
      name: ingress-gateway-configuration 
    spec:
      selector:
        istio: ingressgateway
      servers:
      - port:
          number: 80
          name: http
          protocol: HTTP
        
        host:
        - "*.myweb.com"
    --- 
    kind: VirtualService
    apiVersion: networking.istio.io/v1alpha3
    metadata:
      name: mywebapp
      namespace
    spec:
      hosts:
        - "test1.myweb.com"
      gateways:
        - ingress-gateway-configuration 
      http:
         - route:
           - destination:
               host: web1
               subset: test1
  

• You an also use “Create Matching Routing” model to set routing