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HTTPRoute

Standard Channel in v0.5.0+

The HTTPRoute resource is Beta and part of the Standard Channel in v0.5.0+.

HTTPRoute is a Gateway API type for specifying routing behavior of HTTP requests from a Gateway listener to an API object, i.e. Service.

Spec

The specification of an HTTPRoute consists of:

  • ParentRefs- Define which Gateways this Route wants to be attached to.
  • Hostnames (optional)- Define a list of hostnames to use for matching the Host header of HTTP requests.
  • Rules- Define a list of rules to perform actions against matching HTTP requests. Each rule consists of matches, filters (optional), backendRefs (optional) and timeouts (optional) fields.

The following illustrates an HTTPRoute that sends all traffic to one Service: httproute-basic-example

Attaching to Gateways

Each Route includes a way to reference the parent resources it wants to attach to. In most cases, that's going to be Gateways, but there is some flexibility here for implementations to support other types of parent resources.

The following example shows how a Route would attach to the acme-lb Gateway: 

apiVersion: gateway.networking.k8s.io/v1beta1
kind: HTTPRoute
metadata:
  name: httproute-example
spec:
  parentRefs:
  - name: acme-lb

Note that the target Gateway needs to allow HTTPRoutes from the route's namespace to be attached for the attachment to be successful.

You can also attach routes to specific sections of the parent resource. For example, let's say that the acme-lb Gateway includes the following listeners:

  listeners:
  - name: foo
    protocol: HTTP
    port: 8080
    ...
  - name: bar
    protocol: HTTP
    port: 8090
    ...
  - name: baz
    protocol: HTTP
    port: 8090
    ...

You can bind a route to listener foo only, using the sectionName field in parentRefs:

spec:
  parentRefs:
  - name: acme-lb
    sectionName: foo

Alternatively, you can achieve the same effect by using the port field, instead of sectionName, in the parentRefs:

spec:
  parentRefs:
  - name: acme-lb
    port: 8080

Binding to a port also allows you to attach to multiple listeners at once. For example, binding to port 8090 of the acme-lb Gateway would be more convenient than binding to the corresponding listeners by name:

spec:
  parentRefs:
  - name: acme-lb
    sectionName: bar
  - name: acme-lb
    sectionName: baz

However, when binding Routes by port number, Gateway admins will no longer have the flexibility to switch ports on the Gateway without also updating the Routes. The approach should only be used when a Route should apply to a specific port number as opposed to listeners whose ports may be changed.

Hostnames

Hostnames define a list of hostnames to match against the Host header of the HTTP request. When a match occurs, the HTTPRoute is selected to perform request routing based on rules and filters (optional). A hostname is the fully qualified domain name of a network host, as defined by RFC 3986. Note the following deviations from the “host” part of the URI as defined in the RFC:

  • IPs are not allowed.
  • The : delimiter is not respected because ports are not allowed.

Incoming requests are matched against hostnames before the HTTPRoute rules are evaluated. If no hostname is specified, traffic is routed based on HTTPRoute rules and filters (optional).

The following example defines hostname "my.example.com": 

apiVersion: gateway.networking.k8s.io/v1beta1
kind: HTTPRoute
metadata:
  name: httproute-example
spec:
  hostnames:
  - my.example.com

Rules

Rules define semantics for matching an HTTP request based on conditions, optionally executing additional processing steps, and optionally forwarding the request to an API object.

Matches

Matches define conditions used for matching an HTTP request. Each match is independent, i.e. this rule will be matched if any single match is satisfied.

Take the following matches configuration as an example: 

apiVersion: gateway.networking.k8s.io/v1beta1
kind: HTTPRoute
...
spec:
  rules:
  - matches:
    - path:
        value: "/foo"
      headers:
      - name: "version"
        value: "2"
    - path:
        value: "/v2/foo"

For a request to match against this rule, it must satisfy EITHER of the following conditions:

  • A path prefixed with /foo AND contains the header "version: 2"
  • A path prefix of /v2/foo

If no matches are specified, the default is a prefix path match on “/”, which has the effect of matching every HTTP request.

Filters (optional)

Filters define processing steps that must be completed during the request or response lifecycle. Filters act as an extension point to express additional processing that may be performed in Gateway implementations. Some examples include request or response modification, implementing authentication strategies, rate-limiting, and traffic shaping.

The following example adds header "my-header: foo" to HTTP requests with Host header "my.filter.com". 

apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: http-filter-1
spec:
  hostnames:
    - my.filter.com
  rules:
    - filters:
        - type: RequestHeaderModifier
          requestHeaderModifier:
            add:
              - name: my-header
                value: foo
      backendRefs:
        - name: my-filter-svc1
          weight: 1
          port: 80

API conformance is defined based on the filter type. The effects of ordering multiple behaviors is currently unspecified. This may change in the future based on feedback during the alpha stage.

Conformance levels are defined by the filter type:

  • All "core" filters MUST be supported by implementations.
  • Implementers are encouraged to support "extended" filters.
  • "Implementation-specific" filters have no API guarantees across implementations.

Specifying a core filter multiple times has unspecified or implementation-specific conformance.

All filters are expected to be compatible with each other except for the URLRewrite and RequestRedirect filters, which may not be combined. If an implementation can not support other combinations of filters, they must clearly document that limitation. In cases where incompatible or unsupported filters are specified and cause the Accepted condition to be set to status False, implementations may use the IncompatibleFilters reason to specify this configuration error.

BackendRefs (optional)

BackendRefs defines API objects where matching requests should be sent. If unspecified, the rule performs no forwarding. If unspecified and no filters are specified that would result in a response being sent, a 404 error code is returned.

The following example forwards HTTP requests for prefix /bar to service "my-service1" on port 8080 and HTTP requests for prefix /some/thing with header magic: foo to service "my-service2" on port 8080: 

apiVersion: gateway.networking.k8s.io/v1
kind: GatewayClass
metadata:
  name: example
spec:
  controllerName: acme.io/gateway-controller
  parametersRef:
    name: example
    group: acme.io
    kind: Parameters
---
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: my-gateway
spec:
  gatewayClassName: example
  listeners:  # Use GatewayClass defaults for listener definition.
  - name: http
    protocol: HTTP
    port: 80
---
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: http-app-1
spec:
  parentRefs:
  - name: my-gateway
  hostnames:
  - "foo.com"
  rules:
  - matches:
    - path:
        type: PathPrefix
        value: /bar
    backendRefs:
    - name: my-service1
      port: 8080
  - matches:
    - headers:
      - type: Exact
        name: magic
        value: foo
      queryParams:
      - type: Exact
        name: great
        value: example
      path:
        type: PathPrefix
        value: /some/thing
      method: GET
    backendRefs:
    - name: my-service2
      port: 8080

The following example uses the weight field to forward 90% of HTTP requests to foo.example.com to the "foo-v1" Service and the other 10% to the "foo-v2" Service: 

apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: foo-route
  labels:
    gateway: prod-web-gw
spec:
  hostnames:
  - foo.example.com
  rules:
  - backendRefs:
    - name: foo-v1
      port: 8080
      weight: 90
    - name: foo-v2
      port: 8080
      weight: 10

Reference the backendRef API documentation for additional details on weight and other fields.

Timeouts (optional)

Experimental Channel in v1.0.0+

HTTPRoute timeouts are part of the Experimental Channel in v1.0.0+.

HTTPRoute Rules include a Timeouts field. If unspecified, timeout behavior is implementation-specific.

There are 2 kinds of timeouts that can be configured in an HTTPRoute Rule:

  1. request is the timeout for the Gateway API implementation to send a response to a client HTTP request. This timeout is intended to cover as close to the whole request-response transaction as possible, although an implementation MAY choose to start the timeout after the entire request stream has been received instead of immediately after the transaction is initiated by the client.

  2. backendRequest is a timeout for a single request from the Gateway to a backend. This timeout covers the time from when the request first starts being sent from the gateway to when the full response has been received from the backend. This can be particularly helpful if the Gateway retries connections to a backend.

Because the request timeout encompasses the backendRequest timeout, the value of backendRequest must not be greater than the value of request timeout.

Timeouts are optional, and their fields are of type Duration. A zero-valued timeout ("0s") MUST be interpreted as disabling the timeout. A valid non-zero-valued timeout MUST be >= 1ms.

The following example uses the request field which will cause a timeout if a client request is taking longer than 10 seconds to complete. The example also defines a 2s backendRequest which specifies a timeout for an individual request from the gateway to a backend service timeout-svc: 

apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: timeout-example
spec:
  parentRefs:
  - name: example-gateway
  rules:
  - matches:
    - path:
        type: PathPrefix
        value: /timeout
    timeouts:
      request: 10s
      backendRequest: 2s
    backendRefs:
    - name: timeout-svc
      port: 8080

Reference the timeouts API documentation for additional details.

Backend Protocol
Experimental Channel in v1.0.0+

This concept is part of the Experimental Channel in v1.0.0+.

Some implementations may require the backendRef to be labeled explicitly in order to route traffic using a certain protocol. For Kubernetes Service backends this can be done by specifying the appProtocol field.

Status

Status defines the observed state of HTTPRoute.

RouteStatus

RouteStatus defines the observed state that is required across all route types.

Parents

Parents define a list of the Gateways (or other parent resources) that are associated with the HTTPRoute, and the status of the HTTPRoute with respect to each of these Gateways. When a HTTPRoute adds a reference to a Gateway in parentRefs, the controller that manages the Gateway should add an entry to this list when the controller first sees the route and should update the entry as appropriate when the route is modified.

The following example indicates HTTPRoute "http-example" has been accepted by Gateway "gw-example" in namespace "gw-example-ns": 

apiVersion: gateway.networking.k8s.io/v1beta1
kind: HTTPRoute
metadata:
  name: http-example
...
status:
  parents:
  - parentRefs:
      name: gw-example
      namespace: gw-example-ns
    conditions:
    - type: Accepted
      status: "True"

Merging

Multiple HTTPRoutes can be attached to a single Gateway resource. Importantly, only one Route rule may match each request. For more information on how conflict resolution applies to merging, refer to the API specification.