Some Apps are useful without being accessible outside the cluster, but most need to be available outside of the cluster on one or more HTTP endpoints. In Kf, this is the job of Routes.
By default, each App is accessible to other processes in the cluster using the
cluster internal App address:
app-name.space-name. You can use this address
when you deploy one or more Apps in a cluster that need to communicate with one
another; they allow traffic to go directly from one App to another rather than
out of the cluster and back. This makes communications more secure, faster, and
guaranteed to use the service in the local cluster.
If your App needs to be accessible from outside of the cluster, you'll need to create Routes for it.
The cluster-internal domain
The cluster-internal domain for each App has some special characteristics.
- Using it in your Apps allows East-West (point to point) routing.
- Traffic sent to it is load-balanced between running App Pods.
- You can connect to non-HTTP endpoints using the internal domain.
Routes allow you to create vanity URLs on top of the cluster-internal domain.
App load balancing
Traffic is routed by Istio to healthy instances of an App using a round-robin policy. Currently, this policy can't be changed.
Routes tell the cluster's ingress gateway where to deliver traffic and what to do if no Apps are available on the given address. By default, if no App is available on a Route and the Route receives a request it returns an HTTP 503 status code.
Routes are comprised of three parts: host, domain, and path. For example, in
- The host is
- The domain is
- The path is
Routes must contain a host and domain, but the path is optional. Multiple Routes can share the same host and domain if they specify different paths. Multiple Apps can share the same Route and traffic will be split between them. This is useful if you need to support legacy blue/green deployments. If multiple Apps are bound to different paths, the priority is longest to shortest path.
The following sections describe how to use the
kf CLI to manage Routes.
Developers can list Routes for the current Space using the
$ kf routes Getting Routes in Space: my-space Found 2 Routes in Space my-space HOST DOMAIN PATH APPS echo example.com / echo * example.com /login uaa
Developers can create Routes using the
kf create-route command.
# Create a Route in the targeted Space to match traffic for myapp.example.com/* $ kf create-route example.com --hostname myapp # Create a Route in the Space myspace to match traffic for myapp.example.com/* $ kf create-route -n myspace example.com --hostname myapp # Create a Route in the targeted Space to match traffic for myapp.example.com/mypath* $ kf create-route example.com --hostname myapp --path /mypath # You can also supply the Space name as the first parameter if you have # scripts that rely on the old cf style API. $ kf create-route myspace example.com --hostname myapp # myapp.example.com
After a Route is created, if no Apps are bound to it then an HTTP 503 status code is returned for any matching requests.
Map a Route to your App
Developers can make their App accessible on a Route using the
$ kf map-route MYAPP mycluster.example.com --host myapp --path mypath
Unmap a Route
Developers can remove their App from being accessible on a Route using the
$ kf unmap-route MYAPP mycluster.example.com --host myapp --path mypath
Delete a Route
Developers can delete a Route using the
kf delete-route command.
$ kf delete-route mycluster.example.com --host myapp --path mypath
Deleting a Route will stop traffic from being routed to all Apps listening on the Route.
Declarative Routes in your App manifest
Routes can be managed declaratively in your App manifest file. They will be created if they do not yet exist.
--- applications: - name: my-app # ... routes: - route: example.com - route: www.example.com/path
You can read more about the supported route properties in the manifest documentation.
There are four types that are relevant to routing:
Each App has a Service, which is an abstract name given to all running instances of your App. The name of the Service is the same as the App. A Route represents a single external URL. Routes constantly watch for changes to Apps, when an App requests to be added to a Route, the Route updates its list of Apps and then the VirtualService. A VirtualService represents a single domain and merges a list of all Routes in a Space that belong to that domain.
Istio reads the configuration on VirtualServices to determine how to route traffic.