Version 2.4

Routes and Domains

This topic describes how routes and domains work in Kf, and how developers and administrators configure routes and domains for an App deployed on Kf cluster.

You must create domain and routes to give external access to your application.

Internal Routing

Kf apps can communicate internally with other apps in the cluster directly using the mesh network provided by Anthos Service Mesh without leaving the cluster network. By default, all traffic is encrypted using mutual TLS.

All apps deployed in the Kf cluster come with an internal endpoint configured by default. You can use the address app-name.space-name.svc.cluster.local for internal communication between apps. To use this internal address no extra steps are required. Mutual TLS is enabled by default for internal routes. Note that this internal address is only accessible from the pods running the apps and not accessible from outside the cluster.

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.

Route capabilities

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 URI payroll.mydatacenter.example.com/login:

  • The host is payroll
  • The domain is mydatacenter.example.com
  • The path is /login

Routes must contain a domain, but the host and 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.

Using Routes

The following sections describe how to use the kf CLI to manage Routes.

List Routes

Developers can list Routes for the current Space using the kf routes command.

$ 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

Create Route

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 command.

$ 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 command.

$ 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.

Advanced topics

Routing CRDs

There are four types that are relevant to routing:

  • VirtualService
  • Route
  • Service
  • App

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.