K8s Gateway

+++ title = "k8s_gateway" description = "k8s_gateway - plugin to resolve all types of external Kubernetes resources." weight = 10 tags = [ "plugin" , "k8s" ] categories = [ "plugin", "external", "kubernetes" ] date = "2020-09-19T12:00:00-08:00" repo = "https://github.com/ori-edge/k8s_gateway" home = "https://github.com/ori-edge/k8s_gateway/blob/master/README.md" +++

Description

This plugin is very similar to k8s_external but supporting all types of Kubernetes external resources - Ingress, Service of type LoadBalancer and networking.x-k8s.io/Gateway (when it becomes available).

This plugin relies on it's own connection to the k8s API server and doesn't share any code with the existing kubernetes plugin. The assumption is that this plugin can now be deployed as a separate instance (alongside the internal kube-dns) and act as a single external DNS interface into your Kubernetes cluster(s).

Syntax

k8s_gateway [ZONE...] 

Optionally, you can specify what kind of resources to watch and the default TTL to return in response, e.g.

k8s_gateway example.com {
    resources Ingress
    ttl 10
}

Example

. {
  k8s_gateway example.com
}

With the above configuration the plugin will behave in the following way:

1. All DNS queries will first be matched against the configured zone - example.com
2. If there’s a hit, the next step is to match it against any of the existing Ingress resources. The lookup is performed against FQDNs configured in spec.rules[*].host fields of the Ingress. At this stage, the result can be returned to the user with IPs collected from the .status.loadBalancer.ingress.
3. If no matching Ingress was found, the search continues with the Services objects. Since services don’t really have domain names, the lookup is performed using the serviceName.namespace as the key.
4. If there’s a match, it is returned to the end-user in a similar way, alternatively the plugin responds with NXDOMAIN.

Supported features

k8s_gateway resolves Kubernetes resources with their external IP addresses based on zones specified in the configuration. This plugin will resolve the following type of resources:

[*]: Only resolves service of type LoadBalancer

Currently only supports A-type queries, all other queries result in NODATA responses.

This plugin is NOT supposed to be used for intra-cluster DNS resolution and by default will not contain the default upstream kubernetes plugin.