Learn the HashiCorp Enterprise Stack 
»Consul Clients Outside Kubernetes
Consul clients running on non-Kubernetes nodes can join a Consul cluster running within Kubernetes.
»Auto-join
The recommended way to join a cluster running within Kubernetes is to use the "k8s" cloud auto-join provider.
The auto-join provider dynamically discovers IP addresses to join using
the Kubernetes API. It authenticates with Kubernetes using a standard
kubeconfig file. This works with all major hosted Kubernetes offerings
as well as self-hosted installations. The token in the kubeconfig file
needs to have permissions to list pods in the namespace where Consul servers
are deployed.
The auto-join string below will join a Consul server cluster that is started using the official Helm chart:
$ consul agent -retry-join 'provider=k8s label_selector="app=consul,component=server"'
By default, Consul will join the default gossip port. Pods may set an
annotation consul.hashicorp.com/auto-join-port to an integer value or
a named port to specify the port for the auto-join to return. This enables
different pods to have different exposed ports.
»Networking
Consul typically requires a fully connected network.
Because the Consul Helm chart currently doesn't allow exposing servers' gossip ports via a hostPort,
nodes outside of Kubernetes joining a cluster running within Kubernetes must be able to communicate
to pod IPs via the network. Note that the auto-join provider discussed above will use pod IPs by default.
Consul Enterprise customers may use network segments to enable non-fully-connected topologies. However, out-of-cluster nodes must still be able to communicate with the server pod or host IP addresses.