--- title: Gateway description: Configuration affecting edge load balancer. location: https://istio.io/docs/reference/config/networking/v1alpha3/gateway.html layout: protoc-gen-docs generator: protoc-gen-docs number_of_entries: 6 ---

`Gateway` describes a load balancer operating at the edge of the mesh receiving incoming or outgoing HTTP/TCP connections. The specification describes a set of ports that should be exposed, the type of protocol to use, SNI configuration for the load balancer, etc.

For example, the following Gateway configuration sets up a proxy to act as a load balancer exposing port 80 and 9080 (http), 443 (https), 9443(https) and port 2379 (TCP) for ingress. The gateway will be applied to the proxy running on a pod with labels `app: my-gateway-controller`. While Istio will configure the proxy to listen on these ports, it is the responsibility of the user to ensure that external traffic to these ports are allowed into the mesh.

    apiVersion: networking.istio.io/v1alpha3
    kind: Gateway
    metadata:
      name: my-gateway
      namespace: some-config-namespace
    spec:
      selector:
        app: my-gateway-controller
      servers:
      - port:
          number: 80
          name: http
          protocol: HTTP
        hosts:
        - uk.bookinfo.com
        - eu.bookinfo.com
        tls:
          httpsRedirect: true # sends 301 redirect for http requests
      - port:
          number: 443
          name: https-443
          protocol: HTTPS
        hosts:
        - uk.bookinfo.com
        - eu.bookinfo.com
        tls:
          mode: SIMPLE # enables HTTPS on this port
          serverCertificate: /etc/certs/servercert.pem
          privateKey: /etc/certs/privatekey.pem
      - port:
          number: 9443
          name: https-9443
          protocol: HTTPS
        hosts:
        - "bookinfo-namespace/*.bookinfo.com"
        tls:
          mode: SIMPLE # enables HTTPS on this port
          credentialName: bookinfo-secret # fetches certs from Kubernetes secret
      - port:
          number: 9080
          name: http-wildcard
          protocol: HTTP
        hosts:
        - "*"
      - port:
          number: 2379 # to expose internal service via external port 2379
          name: mongo
          protocol: MONGO
        hosts:
        - "*"

The Gateway specification above describes the L4-L6 properties of a load balancer. A `VirtualService` can then be bound to a gateway to control the forwarding of traffic arriving at a particular host or gateway port.

For example, the following VirtualService splits traffic for `https://uk.bookinfo.com/reviews`, `https://eu.bookinfo.com/reviews`, `http://uk.bookinfo.com:9080/reviews`, `http://eu.bookinfo.com:9080/reviews` into two versions (prod and qa) of an internal reviews service on port 9080. In addition, requests containing the cookie “user: dev-123” will be sent to special port 7777 in the qa version. The same rule is also applicable inside the mesh for requests to the “reviews.prod.svc.cluster.local” service. This rule is applicable across ports 443, 9080. Note that `http://uk.bookinfo.com` gets redirected to `https://uk.bookinfo.com` (i.e. 80 redirects to 443).

    apiVersion: networking.istio.io/v1alpha3
    kind: VirtualService
    metadata:
      name: bookinfo-rule
      namespace: bookinfo-namespace
    spec:
      hosts:
      - reviews.prod.svc.cluster.local
      - uk.bookinfo.com
      - eu.bookinfo.com
      gateways:
      - some-config-namespace/my-gateway
      - mesh # applies to all the sidecars in the mesh
      http:
      - match:
        - headers:
            cookie:
              exact: "user=dev-123"
        route:
        - destination:
            port:
              number: 7777
            host: reviews.qa.svc.cluster.local
      - match:
        - uri:
            prefix: /reviews/
        route:
        - destination:
            port:
              number: 9080 # can be omitted if it's the only port for reviews
            host: reviews.prod.svc.cluster.local
          weight: 80
        - destination:
            host: reviews.qa.svc.cluster.local
          weight: 20

The following VirtualService forwards traffic arriving at (external) port 27017 to internal Mongo server on port 5555. This rule is not applicable internally in the mesh as the gateway list omits the reserved name `mesh`.

    apiVersion: networking.istio.io/v1alpha3
    kind: VirtualService
    metadata:
      name: bookinfo-Mongo
      namespace: bookinfo-namespace
    spec:
      hosts:
      - mongosvr.prod.svc.cluster.local # name of internal Mongo service
      gateways:
      - some-config-namespace/my-gateway # can omit the namespace if gateway is in same
                                           namespace as virtual service.
      tcp:
      - match:
        - port: 27017
        route:
        - destination:
            host: mongo.prod.svc.cluster.local
            port:
              number: 5555

It is possible to restrict the set of virtual services that can bind to a gateway server using the namespace/hostname syntax in the hosts field. For example, the following Gateway allows any virtual service in the ns1 namespace to bind to it, while restricting only the virtual service with foo.bar.com host in the ns2 namespace to bind to it.

    apiVersion: networking.istio.io/v1alpha3
    kind: Gateway
    metadata:
      name: my-gateway
      namespace: some-config-namespace
    spec:
      selector:
        app: my-gateway-controller
      servers:
      - port:
          number: 80
          name: http
          protocol: HTTP
        hosts:
        - "ns1/*"
        - "ns2/foo.bar.com"

## Gateway

Field | Type | Description
--- | --- | ---
`servers` | `Server[]` | REQUIRED: A list of server specifications.
`selector` | `map<string, string>` | REQUIRED: One or more labels that indicate a specific set of pods/VMs on which this gateway configuration should be applied. The scope of label search is restricted to the configuration namespace in which the the resource is present. In other words, the Gateway resource must reside in the same namespace as the gateway workload instance.

## Port

Port describes the properties of a specific port of a service.

Field | Type | Description
--- | --- | ---
`number` | `uint32` | REQUIRED: A valid non-negative integer port number.
`protocol` | `string` | REQUIRED: The protocol exposed on the port. MUST BE one of HTTP|HTTPS|GRPC|HTTP2|MONGO|TCP|TLS. TLS implies the connection will be routed based on the SNI header to the destination without terminating the TLS connection.
`name` | `string` | Label assigned to the port.

## Server

`Server` describes the properties of the proxy on a given load balancer port. For example,

    apiVersion: networking.istio.io/v1alpha3
    kind: Gateway
    metadata:
      name: my-ingress
    spec:
      selector:
        app: my-ingress-gateway
      servers:
      - port:
          number: 80
          name: http2
          protocol: HTTP2
        hosts:
        - "*"

Another example

    apiVersion: networking.istio.io/v1alpha3
    kind: Gateway
    metadata:
      name: my-tcp-ingress
    spec:
      selector:
        app: my-tcp-ingress-gateway
      servers:
      - port:
          number: 27018
          name: mongo
          protocol: MONGO
        hosts:
        - "*"

The following is an example of TLS configuration for port 443

    apiVersion: networking.istio.io/v1alpha3
    kind: Gateway
    metadata:
      name: my-tls-ingress
    spec:
      selector:
        app: my-tls-ingress-gateway
      servers:
      - port:
          number: 443
          name: https
          protocol: HTTPS
        hosts:
        - "*"
        tls:
          mode: SIMPLE
          serverCertificate: /etc/certs/server.pem
          privateKey: /etc/certs/privatekey.pem

Field | Type | Description
--- | --- | ---
`port` | `Port` | REQUIRED: The Port on which the proxy should listen for incoming connections.
`hosts` | `string[]` | REQUIRED. One or more hosts exposed by this gateway. While typically applicable to HTTP services, it can also be used for TCP services using TLS with SNI. A host is specified as a `dnsName` with an optional `namespace/` prefix. The `dnsName` should be specified using FQDN format, optionally including a wildcard character in the left-most component (e.g., `prod/*.example.com`). Set the `dnsName` to `*` to select all `VirtualService` hosts from the specified namespace (e.g.,`prod/*`). If no `namespace/` is specified, the `VirtualService` hosts will be selected from any available namespace. Any associated `DestinationRule` in the same namespace will also be used. A `VirtualService` must be bound to the gateway and must have one or more hosts that match the hosts specified in a server. The match could be an exact match or a suffix match with the server’s hosts. For example, if the server’s hosts specifies `*.example.com`, a `VirtualService` with hosts `dev.example.com` or `prod.example.com` will match. However, a `VirtualService` with host `example.com` or `newexample.com` will not match. NOTE: Only virtual services exported to the gateway’s namespace (e.g., `exportTo` value of `*`) can be referenced. Private configurations (e.g., `exportTo` set to `.`) will not be available. Refer to the `exportTo` setting in `VirtualService`, `DestinationRule`, and `ServiceEntry` configurations for details.
`tls` | `Server.TLSOptions` | Set of TLS related options that govern the server’s behavior. Use these options to control if all http requests should be redirected to https, and the TLS modes to use.
`defaultEndpoint` | `string` | The loopback IP endpoint or Unix domain socket to which traffic should be forwarded to by default. Format should be `127.0.0.1:PORT` or `unix:///path/to/socket` or `unix://@foobar` (Linux abstract namespace).

## Server.TLSOptions

Field | Type | Description
--- | --- | ---
`httpsRedirect` | `bool` | If set to true, the load balancer will send a 301 redirect for all http connections, asking the clients to use HTTPS.
`mode` | `Server.TLSOptions.TLSmode` | Optional: Indicates whether connections to this port should be secured using TLS. The value of this field determines how TLS is enforced.
`serverCertificate` | `string` | REQUIRED if mode is `SIMPLE` or `MUTUAL`. The path to the file holding the server-side TLS certificate to use.
`privateKey` | `string` | REQUIRED if mode is `SIMPLE` or `MUTUAL`. The path to the file holding the server’s private key.
`caCertificates` | `string` | REQUIRED if mode is `MUTUAL`. The path to a file containing certificate authority certificates to use in verifying a presented client side certificate.
`credentialName` | `string` | The credentialName stands for a unique identifier that can be used to identify the serverCertificate and the privateKey. The credentialName appended with suffix “-cacert” is used to identify the CaCertificates associated with this server. Gateway workloads capable of fetching credentials from a remote credential store such as Kubernetes secrets, will be configured to retrieve the serverCertificate and the privateKey using credentialName, instead of using the file system paths specified above. If using mutual TLS, gateway workload instances will retrieve the CaCertificates using credentialName-cacert. The semantics of the name are platform dependent. In Kubernetes, the default Istio supplied credential server expects the credentialName to match the name of the Kubernetes secret that holds the server certificate, the private key, and the CA certificate (if using mutual TLS). Set the `ISTIO_META_USER_SDS` metadata variable in the gateway’s proxy to enable the dynamic credential fetching feature.
`subjectAltNames` | `string[]` | A list of alternate names to verify the subject identity in the certificate presented by the client.
`minProtocolVersion` | `Server.TLSOptions.TLSProtocol` | Optional: Minimum TLS protocol version.
`maxProtocolVersion` | `Server.TLSOptions.TLSProtocol` | Optional: Maximum TLS protocol version.
`cipherSuites` | `string[]` | Optional: If specified, only support the specified cipher list. Otherwise default to the default cipher list supported by Envoy.

## Server.TLSOptions.TLSProtocol

TLS protocol versions.

Name | Description
--- | ---
`TLS_AUTO` | Automatically choose the optimal TLS version.
`TLSV1_0` | TLS version 1.0
`TLSV1_1` | TLS version 1.1
`TLSV1_2` | TLS version 1.2
`TLSV1_3` | TLS version 1.3

## Server.TLSOptions.TLSmode

TLS modes enforced by the proxy

Name | Description
--- | ---
`PASSTHROUGH` | The SNI string presented by the client will be used as the match criterion in a VirtualService TLS route to determine the destination service from the service registry.
`SIMPLE` | Secure connections with standard TLS semantics.
`MUTUAL` | Secure connections to the upstream using mutual TLS by presenting client certificates for authentication.
`AUTO_PASSTHROUGH` | Similar to the passthrough mode, except servers with this TLS mode do not require an associated VirtualService to map from the SNI value to service in the registry. The destination details such as the service/subset/port are encoded in the SNI value. The proxy will forward to the upstream (Envoy) cluster (a group of endpoints) specified by the SNI value. This server is typically used to provide connectivity between services in disparate L3 networks that otherwise do not have direct connectivity between their respective endpoints. Use of this mode assumes that both the source and the destination are using Istio mTLS to secure traffic.