Gateway sources

The gateway-grpcroute, gateway-httproute, gateway-tcproute, gateway-tlsroute, and gateway-udproute sources create DNS entries based on their respective gateway.networking.k8s.io resources.

Filtering the Routes considered

These sources support the --label-filter flag, which filters *Route resources by a set of labels.

Domain names

To calculate the Domain names created from a *Route, this source first collects a set of domain names from the *Route.

It then iterates over each of the status.parents with a matching Gateway and at least one matching listener. For each matching listener, if the listener has a hostname, it narrows the set of domain names from the *Route to the portion that overlaps the hostname. If a matching listener does not have a hostname, it uses the un-narrowed set of domain names.

Domain names from Route

The set of domain names from a *Route is sourced from the following places:

If the *Route is a GRPCRoute, HTTPRoute, or TLSRoute, adds each of thespec.hostnames.
Adds the hostnames from any external-dns.alpha.kubernetes.io/hostname annotation on the *Route. This behavior is suppressed if the --ignore-hostname-annotation flag was specified.
If no endpoints were produced by the previous steps or the --combine-fqdn-annotation flag was specified, then adds hostnames generated from any--fqdn-template flag.
If no endpoints were produced by the previous steps, each attached Gateway listener will use its hostname, if present.

Matching Gateways

Matching Gateways are discovered by iterating over the *Route's status.parents:

Ignores parents with a parentRef.group other than gateway.networking.k8s.io or a parentRef.kind other than Gateway.

If the --gateway-name flag was specified, ignores parents with a parentRef.name other than the specified value.

For example, given the following HTTPRoute:

apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: echo
spec:
  hostnames:
    - echoserver.example.org
  parentRefs:
    - group: networking.k8s.io
      kind: Gateway
      name: internal
---
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: echo2
spec:
  hostnames:
    - echoserver2.example.org
  parentRefs:
    - group: networking.k8s.io
      kind: Gateway
      name: external

And using the --gateway-name=external flag, only the echo2 HTTPRoute will be considered for DNS entries.

If the --gateway-namespace flag was specified, ignores parents with a parentRef.namespace other than the specified value.
If the --gateway-label-filter flag was specified, ignores parents whose Gateway does not match the specified label filter.
Ignores parents whose Gateway either does not exist or has not accepted the route.

Matching listeners

Iterates over all listeners for the parent's parentRef.sectionName:

Ignores listeners whose protocol field does not match the kind of the *Route per the following table:

kind	protocols
GRPCRoute	HTTP, HTTPS
HTTPRoute	HTTP, HTTPS
TCPRoute	TCP
TLSRoute	TLS
UDPRoute	UDP

If the parent's parentRef.port port is specified, ignores listeners without a matching port.
Ignores listeners which specify an allowedRoutes which does not allow the route.

Targets

The targets of the DNS entries created from a *Route are sourced from the following places:

If a matching parent Gateway has an external-dns.alpha.kubernetes.io/target annotation, uses the values from that.
Otherwise, iterates over that parent Gateway's status.addresses, adding each address's value.

The targets from each parent Gateway matching the *Route are then combined and de-duplicated.

Dualstack Routes

Gateway resources may be served from an external-loadbalancer which may support both IPv4 and "dualstack" (both IPv4 and IPv6) interfaces. When using the AWS Route53 provider, External DNS Controller will always create both A and AAAA alias DNS records by default, regardless of whether the load balancer is dual stack or not.

Example

apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: echo
spec:
  hostnames:
    - echoserver.example.org
  rules:
    - backendRefs:
        - group: ""
          kind: Service
          name: echo
          port: 1027
          weight: 1
      matches:
        - path:
            type: PathPrefix
            value: /echo

4.7 KiB Raw Blame History