Developers and administrators can configure routes and domains for their apps using the Cloud Foundry Command Line Interface (cf CLI). This topic describes how routes and domains work in VMware Tanzu Application Service for VMs (TAS for VMs). For more information about routing capabilities in TAS for VMs, see HTTP Routing.

Routes

The TAS for VMs Gorouter routes requests to apps by associating an app with an address, known as a route. This is known as a mapping. Use the cf CLI cf map-route command to associate an app and route.

The routing tier compares each request with a list of all the routes mapped to apps and attempts to find the best match. For example, the Gorouter would make the following matches for the two routes myapp.shared-domain.example.com and myapp.shared-domain.example.com/products:

Request Matched Route
http://myapp.shared-domain.example.com myapp.shared-domain.example.com
http://myapp.shared-domain.example.com/contact myapp.shared-domain.example.com
http://myapp.shared-domain.example.com/products myapp.shared-domain.example.com/products
http://myapp.shared-domain.example.com/products/123 myapp.shared-domain.example.com/products
http://products.shared-domain.example.com No match; 404

The Gorouter does not use a route to match requests until the route is mapped to an app. In the above example, products.shared-domain.example.com may have been created as a route in TAS for VMs, but until it is mapped to an app, requests for the route receive a 404 error.

The routing tier knows the location of instances for apps mapped to routes. Once the routing tier determines a route as the best match for a request, it makes a load-balancing calculation using a round-robin algorithm, and forwards the request to an instance of the mapped app.

Developers can map many apps to a single route, resulting in load-balanced requests for the route across all instances of all mapped apps. This approach enables the blue/green rolling deployment strategy. Developers can also map an individual app to multiple routes, enabling access to the app from many URLs. The number of routes that can be mapped to each app is approximately 1000 (128 KB).

Routes belong to a space, and developers can only map apps to a route in the same space.

Routes are globally unique. Developers in one space cannot create a route with the same URL as developers in another space, regardless of which orgs control these spaces.

HTTP vs. TCP routes

By default, TAS for VMs only supports routing of HTTP requests to apps.

Routes are considered HTTP if they are created from HTTP domains, and TCP if they are created from TCP domains. For more information, see HTTP vs. TCP Shared Domains.

HTTP routes include a domain, an optional hostname, and an optional context path. shared-domain.example.com, myapp.shared-domain.example.com, and myapp.shared-domain.example.com/products are all examples of HTTP routes. Apps should listen to the localhost port defined by the $PORT environment variable, which is 8080 on Diego. As an example, requests to myapp.shared-domain.example.com would be routed to the app container at localhost:8080.

Note You can update the ports on which an app can receive requests through the Cloud Controller API. For more information, see Configuring Apps to Listen on Custom Ports (Beta).

  • Requests to HTTP routes must be sent to ports 80 or 443.
  • Ports cannot be reserved for HTTP routes.

TCP routes include a domain and a route port. A route port is the port clients make requests to. This is not the same port as what an app pushed to Cloud Foundry listens on. tcp.shared-domain.example.com:60000 is an example of a TCP route. Just as for HTTP routes, apps should listen to the localhost port defined by the $PORT environment variable, which is 8080 on Diego. As an example, requests to tcp.shared-domain.example.com:60000 would be routed to the app container at localhost:8080.

  • Once a port is reserved for a route, it cannot be reserved for another route.
  • Hostname and path are not supported for TCP routes.

Internal container-to-container routes

TAS for VMs apps can communicate with each other securely and directly over internal routes that never leave the platform.

Apps running on Windows cells cannot use internal, container-to-container routes.

To create an internal route:

  1. Use the cf map-route command with an internal domain. For example:

    $ cf map-route app apps.internal --hostname app
    • After an internal route is mapped to an app, the route resolves to IP addresses of the app instances. The IP addresses are visible in the app container: 
      $ cf ssh app
vcap@1234:~$ host app.apps.internal
app.apps.internal has address 10.255.169.200
app.apps.internal has address 10.255.49.7
app.apps.internal has address 10.255.49.77
    • To resolve individual instances, prepend the index to the internal route. 
      vcap@1234:~$ host 1.app.apps.internal
1.app.apps.internal has address 10.255.49.7

  2. Create a network policy that allows your apps to communicate with each other. By default, apps cannot communicate over the container network. For more information, see Configuring Container-to-Container Networking and add-network-policy in the Cloud Foundry CLI Reference Guide.

Create a route

When a developer creates a route using the cf CLI, TAS for VMs determines whether the route is an HTTP or a TCP route based on the domain. To create a HTTP route, a developer must choose an HTTP domain. To create a TCP route, a developer must choose a TCP domain.

Domains in TAS for VMs provide a namespace from which to create routes. To list available domains for a targeted organization, use the cf domains command. For more information about domains, see Domains.

The following sections describe how developers can create HTTP and TCP routes for different use cases.

Create an HTTP route with hostname

In TAS for VMs, a hostname is the label that indicates a subdomain of the domain associated with the route. Given a domain shared-domain.example.com, a developer can create the route myapp.shared-domain.example.com by specifying the hostname myapp with the cf create-route command as shown in this example:

  • cf CLI v7

    $ cf create-route shared-domain.example.com --hostname myapp
Creating route myapp.shared-domain.example.com for org my-org / space my-space as username@example.com...
OK

    The cf CLI v7 create-route command does not require the space as an argument. It uses the space you are currently targeting.

  • cf CLI v6

    $ cf create-route my-space shared-domain.example.com --hostname myapp
Creating route myapp.shared-domain.example.com for org my-org / space my-space as username@example.com...
OK

This command instructs TAS for VMs to only route requests to apps mapped to this route for the following URLs:

  • http://myapp.shared-domain.example.com
  • https://myapp.shared-domain.example.com
  • Any path under either of the above URLs, such as http://myapp.shared-domain.example.com/bar

Create an HTTP route without hostname

This approach creates a route with the same address as the domain itself and is permitted for private domains only. For more information, see Private Domains.

A developer can create a route from the domain private-domain.example.com with no hostname with the cf create-route command:

  • cf CLI v7 
    $ cf create-route private-domain.example.com
Creating route private-domain.example.com for org my-org / space my-space as username@example.com...
OK
  • cf CLI v6 
    $ cf create-route my-space private-domain.example.com
Creating route private-domain.example.com for org my-org / space my-space as username@example.com...
OK

If DNS has been configured correctly, this command instructs TAS for VMs to route requests to apps mapped to this route from these URLs:

  • http://private-domain.example.com
  • https://private-domain.example.com
  • Any path under either of the above URLs, such as http://private-domain.example.com/foo

If there are no other routes for the domain, requests to any subdomain, such as http://foo.private-domain.example.com, will fail.

A developer can also create routes for subdomains with no hostnames. The following command creates a route from the subdomain foo.private-domain.example.com:

  • cf CLI v7 
    $ cf create-route foo.private-domain.example.com
Creating route foo.private-domain.example.com for org my-org / space my-space as username@example.com...
OK
  • cf CLI v6 
    $ cf create-route my-space foo.private-domain.example.com
Creating route foo.private-domain.example.com for org my-org / space my-space as username@example.com...
OK

Assuming DNS has been configured for this subdomain, this command instructs TAS for VMs to route requests to apps mapped to this route from these URLs:

  • http://foo.private-domain.example.com
  • https://foo.private-domain.example.com
  • Any path under either of the above URLs, such as http://foo.private-domain.example.com/foo

Create an HTTP route with wildcard hostname

An app mapped to a wildcard route acts as a fallback app for route requests if the requested route does not exist. To create a wildcard route, use an asterisk for the hostname.

A developer can create a wildcard route from the domain foo.shared-domain.example.com by running:

  • cf CLI v7 
    $ cf create-route foo.shared-domain.example.com --hostname '*'
Creating route *.foo.shared-domain.example.com for org my-org / space my-space as username@example.com...
OK
  • cf CLI v6 
    $ cf create-route my-space foo.shared-domain.example.com --hostname '*'
Creating route *.foo.shared-domain.example.com for org my-org / space my-space as username@example.com...
OK

If a client sends a request to http://app.foo.shared-domain.example.com by accident, attempting to reach myapp.foo.shared-domain.example.com, TAS for VMs routes the request to the app mapped to the route *.foo.shared-domain.example.com.

Create an HTTP route with a path

Developers can use paths to route requests for the same hostname and domain to different apps.

A developer can create three routes using the same hostname and domain in the space my-space by running:

  • cf CLI v7

    $ cf create-route shared-domain.example.com --hostname store --path products
Creating route store.shared-domain.example.com/products for org my-org / space my-space as username@example.com...
OK

    $ cf create-route shared-domain.example.com --hostname store --path orders
Creating route store.shared-domain.example.com/orders for org my-org / space my-space as username@example.com...
OK

    $ cf create-route shared-domain.example.com --hostname store
Creating route store.shared-domain.example.com for org my-org / space my-space as username@example.com...
OK

  • cf CLI v6 - If you want to create a route without a path using cf CLI v6, you must run the commands in the order below. Create the route without a path first, and then create any routes with a path. If you do not need a route without a path, then this order is not required.

    $ cf create-route my-space shared-domain.example.com --hostname store
Creating route store.shared-domain.example.com for org my-org / space my-space as username@example.com...
OK

    $ cf create-route my-space shared-domain.example.com --hostname store --path products
Creating route store.shared-domain.example.com/products for org my-org / space my-space as username@example.com...
OK

    $ cf create-route my-space shared-domain.example.com --hostname store --path orders
Creating route store.shared-domain.example.com/orders for org my-org / space my-space as username@example.com...
OK

The developer can then map the new routes to different apps by following the steps in Map a Route to Your App.

If the developer maps the first route with path products to the products app, the second route with path orders to the orders app, and the last route to the storefront app. After this:

  • TAS for VMs routes requests to http://store.shared-domain.example.com/products to the products app.
  • TAS for VMs routes requests to http://store.shared-domain.example.com/orders to the orders app.
  • TAS for VMs routes requests to http://store.shared-domain.example.com to the storefront app.

TAS for VMs attempts to match routes with a path first, and then attempts to match host and domain.

Additional notes:

  • Routes with the same domain and hostname but different paths can only be created in the same space. Private domains do not have this limitation.
  • TAS for VMs does not route requests for context paths to the root context of an app. Apps must serve requests on the context path.

Create a TCP route with a port

cf CLI v7: To create an arbitrary port when the --port is not used, run the command shown below. Note that the --random-port flag is no longer supported, and the behavior it provided is now the default.

$ cf create-route my-space tcp.shared-domain.example.com
Creating route tcp.shared-domain.example.com for org my-org / space my-space as [email protected]...
OK
Route tcp.shared-domain.example.com:60034 has been created

cf CLI v6: A developer can create a TCP route for tcp.shared-domain.example.com on an arbitrary port. If the clients of the app can accommodate addressing an arbitrary port, then developers should use the --random-port to instruct TAS for VMs to pick a port for your route. To create a TCP route for tcp.shared-domain.example.com on an arbitrary port, run:

$ cf create-route my-space tcp.shared-domain.example.com --random-port
Creating route tcp.shared-domain.example.com for org my-org / space my-space as [email protected]...
OK
Route tcp.shared-domain.example.com:60034 has been created

In this example, TAS for VMs routes requests to tcp.shared-domain.example.com:60034 to apps mapped to this route.

To request a specific port, a developer can use the --port flag, so long as the port is not reserved for another space. To create a TCP route for tcp.shared-domain.example.com on port 60035, run:

$ cf create-route my-space tcp.shared-domain.example.com --port 60035
Creating route tcp.shared-domain.example.com:60035 for org my-org / space my-space as [email protected]...
OK

List routes

Developers can list routes for the current space with the cf routes command. A route is uniquely identified by the combination of hostname, domain, and path. Note that, as of cf CLI v7, port no longer appears in the table.

$ cf routes
Getting routes as [email protected] ...

space      host     domain              		port   path       type	apps
my-space   myapp    shared-domain.example.com						    myapp
my-space   myapp    private-domain.example.com						    myapp
my-space   store    shared-domain.example.com		   /products   	    products
my-space   store    shared-domain.example.com		   /orders     	    orders
my-space   store    shared-domain.example.com                	        storefront
my-space		    shared-domain.example.com	60000 			  tcp   tcp-app

Developers can only see routes in spaces where they are members.

Important cf CLI v7 removes the port and path columns from the output.

Check routes

Developers cannot create a route that is already taken. To check whether a route is available, developers can use the cf check-route command.

To check whether a route with the hostname store and the domain shared-domain.example.com and the path products exists, run:

  • cf CLI v7: 
    $ cf check-route shared-domain.example.com --hostname store --path /products
Checking for route...
OK
Route store.shared-domain.example.com/products does exist
  • cf CLI v6: 
    $ cf check-route store shared-domain.example.com --path /products
Checking for route...
OK
Route store.shared-domain.example.com/products does exist

Map a route to your app

For an app to receive requests to a route, developers must map the route to the app with the cf map-route command. If the route does not already exist, this command creates it.

Any app that is not routed to port 80 or port 443 must be explicitly mapped using the cf map-route command. Otherwise, the route is automatically mapped to port 443.

Developers can create and reserve routes for later use by following the steps in Manually Map a Route. Or they can map routes to their app immediately as part of a push by following the steps in Map a Route with App Push.

Changes to route mappings are executed asynchronously. On startup, an app will be accessible at its route within a few seconds. Similarly, upon mapping a new route to a running app, the app will be accessible at this route within a few seconds of the CLI exiting successfully.

Manually map a route

Given the following routes and apps:

Route Apps
store.shared-domain.example.com/products products
store.shared-domain.example.com/orders orders
store.shared-domain.example.com storefront
tcp.shared-domain.example.com:60000 tcp-app

The following commands map the above routes to their respective apps. Developers use hostname, domain, and path to uniquely identify a route to map their apps to.

$ cf map-route products shared-domain.example.com --hostname store --path products
$ cf map-route orders shared-domain.example.com --hostname store --path orders
$ cf map-route storefront shared-domain.example.com --hostname store
$ cf map-route tcp-app tcp.shared-domain.example.com --port 60000

The following command maps the wildcard route *.foo.shared-domain.example.com to the app myfallbackapp.

$ cf map-route myfallbackapp foo.shared-domain.example.com --hostname '*'

In cf CLI v8, the following command maps the route h2app.shared-domain.example.com as an HTTP/2 route to the HTTP/2 app h2app.

$ cf map-route h2app shared-domain.example.com --hostname h2app --destination-protocol http2

In cf CLI v8, the following command maps the route h2app.shared-domain.example.com as an HTTP/2 route to the HTTP/2 app h2app.

$ cf map-route h2app shared-domain.example.com --hostname h2app --destination-protocol http2

Map a route with app push

Developers can map a route to their app with the cf push command.

If a domain or hostname is not specified, then a route will be created using the app name and the default shared domain (see Shared Domains). The following command pushes the app myapp, creating the route myapp.shared-domain.example.com from the default shared domain shared-domain.example.com. If the route has not already been created in another space this command also maps it to the app.

$ cf push myapp

To customize the route during push:

cf CLI v6: Specify the domain using the -d flag and the hostname with the --hostname flag. The following command creates the foo.private-domain.example.com route for myapp:

$ cf push myapp -d private-domain.example.com --hostname foo

cf CLI v7: The following command creates the foo.private-domain.example.com route for myapp. Domain and hostname must be specified in the manifest using the routes property.

$ cf push myapp private-domain.example.com

To map a TCP route during push, specify a TCP domain and request a random port using --random-route. To specify a port, push the app without a route, then create and map the route manually by following the steps in Create a TCP Route with a Port. If you are using cf CLI v6, use the -d flag to specify the domain.

$ cf push tcp-app tcp.shared-domain.example.com --random-route

Map a route using app manifest

Developers can map a route to their app with a manifest by editing the route attribute to specify the host, domain, port and/or path components of the route. For more information, see Deploying with App Manifests.

Map a route to multiple apps

TAS for VMs allows multiple apps, or versions of the same app, to be mapped to the same route. This feature enables Blue-Green deployment. For more information see Using Blue-Green Deployment to Reduce Downtime and Risk.

Routing multiple apps to the same route may cause undesirable behavior in some situations by routing incoming requests randomly to one of the apps on the shared route.

For more information about troubleshooting this problem, see the Routing Conflict section of the Troubleshooting App Deployment and Health topic.

Map multiple routes to one app

You can have multiple routes to an app, but those routes cannot have different context paths.

The following routes are valid for a single app:

Route 1 Route 2
myapp.example.com myapp.apps.cf.example.com
myapp.example.com/foo myapp.apps.cf.example.com/foo

The following routes are not valid for a single app:

Route 1 Route 2
myapp.example.com/foo myapp.apps.cf.example.com/bar
myapp.apps.cf.example.com/foo myapp.example.com/bar

Map an internal route to an app

You can map an internal route to any app. This internal route allows your app to communicate with other apps without leaving the platform. Once mapped, this route becomes available to all other apps on the platform.

This example creates a foo.apps.internal internal route for myapp:

$ cf map-route myapp apps.internal --hostname foo

Unmap a route

Developers can remove a route from an app using the cf unmap-route command. The route remains reserved for later use in the space where it was created until the route is deleted.

To unmap an HTTP route from an app, identify the route using the hostname, domain, and path:

$ cf unmap-route tcp-app private-domain.example.com --hostname myapp --path mypath

To unmap a TCP route from an app, identify the route using the domain and port:

$ cf unmap-route tcp-app tcp.shared-domain.example.com --port 60000

Delete a route

Developers can delete a route from a space using the cf delete-route command.

To delete a HTTP route, identify the route using the hostname, domain, and path:

$ cf delete-route private-domain.example.com --hostname myapp --path mypath

To delete a TCP route, identify the route using the domain and port.

$ cf delete-route tcp.private-domain.example.com --port 60000

Routing requests to a specific app instance

Users can route HTTP requests to a specific app instance using the header X-Cf-App-Instance.

Important Use of the X-Cf-App-Instance header is only available for users on the Diego architecture.

The format of the header is X-Cf-App-Instance: APP_GUID:APP_INDEX.

APP_GUID is an internal identifier for your app. Use the cf APP-NAME --guid command to discover the APP_GUID for your app.

$ cf app myapp --guid

APP_INDEX, for example 0,1, 2, or 3, is an identifier for a particular app instance. Use the CLI command cf app APP-NAME to get statistics on each instance of a particular app.

$ cf app myapp

The following example shows a request made to instance 9 of an app with GUID 5cdc7595-2e9b-4f62-8d5a-a86b92f2df0e and mapped to route myapp.private-domain.example.com.

$ curl myapp.private-domain.example.com -H "X-Cf-App-Instance: 5cdc7595-2e9b-4f62-8d5a-a86b92f2df0e:9"

If the X-Cf-App-Instance header is set to an invalid value, Gorouter returns a 400 status code and the response from Gorouter contains a X-Cf-Routererror header with more information about the error. Before the routing release v0.197.0, Gorouter returned a 404 error.

The following table describes the possible error responses:

X-Cf-Routererror Value Reason for Error Response Body
invalid_cf_app_instance_header The value provided for X-Cf-App-Instance was an incorrectly formatted GUID. None
unknown_route The value provided for X-Cf-App-Instance is a correctly formatted GUID, but there is no instance found with that GUID for the route requested. 400 Bad Request: Requested instance ('1') with guid ('aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa') does not exist for route ('myroute.cf.com')

Domains

The term “domain” in this topic differs from its common use and is specific to TAS for VMs. Likewise, shared domain and private domain refer to resources with specific meaning in TAS for VMs. The use of “domain name”, “root domain”, and “subdomain” refer to DNS records.

Domains indicate to a developer that requests for any route created from the domain are routed to TAS for VMs. This requires DNS to be configured out-of-band to resolve the domain name to the IP address of a load balancer configured to forward requests to the TAS for VMs routers. For more information about configuring DNS, see DNS for Domains.

List domains for an org

When creating a route, developers select from domains available to them. Use the cf domains command to view a list of available domains for the targeted org:

$ cf domains
Getting domains in org my-org as [email protected]... OK
name                     status   type
shared-domain.example.com        shared
tcp.shared-domain.example.com    shared   tcp
private-domain.example.com       owned

This example displays three available domains: a shared HTTP domain shared-domain.example.com, a shared TCP domain tcp.shared-domain.example.com, and a private domain private-domain.example.com. For more information, see Shared Domains and Private Domains.

HTTP vs. TCP domains

HTTP domains indicate to a developer that only requests using the HTTP protocol are routed to apps mapped to routes created from the domain. Routing for HTTP domains is layer 7 and offers features like custom hostnames, sticky sessions, and TLS termination.

TCP domains indicate to a developer that requests over any TCP protocol, including HTTP, are routed to apps mapped to routes created from the domain. Routing for TCP domains is layer 4 and protocol agnostic, so many features available to HTTP routing are not available for TCP routing. TCP domains are defined as being associated with the TCP Router Group. The TCP Router Group defines the range of ports available to be reserved with TCP Routes. Currently, only Shared Domains can be TCP.

Note By default, TAS for VMs only supports routing of HTTP requests to apps.

Shared domains

Admins manage shared domains, which are available to users in all orgs of a TAS for VMs deployment. An admin can offer multiple shared domains to users. For example, an admin may offer developers the choice of creating routes for their apps from shared-domain.example.com and cf.some-company.com.

If a developer pushes an app without specifying a domain, a route is created for it from the first shared domain created in the system. All other operations involving route require the domain be specified (see Routes).

When using shared domains, you cannot have routes with the same hostname and domain across different orgs and spaces.

Shared domains are HTTP by default, but can be configured to be TCP when associated with the TCP router group.

Create a shared domain

Admins can create an HTTP shared domain with the cf create-shared-domain command:

$ cf create-shared-domain shared-domain.example.com

To create a TCP shared domain, first discover the name of the TCP router group.

Important cf CLI v7 does not support TCP routing or creating shared domains with router groups.

$ cf router-groups
Getting router groups as admin ...
name          type
default-tcp   tcp
Then create the shared domain using the `--router-group` option to associate the domain with the TCP router group. 
$ cf create-shared-domain tcp.shared-domain.example.com --router-group default-tcp

Delete a shared domain

Admins can delete a shared domain from TAS for VMs with the cf delete-shared-domain command:

$ cf delete-shared-domain example.com

Internal domain

The internal domain is a special type of shared domain used for app communication internal to the platform. When you enable service discovery, the internal domain apps.internal becomes available for route mapping.

Admins can configure multiple internal domains. First add a custom internal domain name to the internal_domains property on the bosh-dns-adapter job. Then create an internal domain using the --internal option:

$ cf create-shared-domain shared-domain.example.com --internal

The --router-group option is not used with internal domains.

Private domains

Org managers can add private domains, or custom domains, and give members of the org permission to create routes for privately registered domain names.

Private domains can be shared with other orgs and spaces. These are referred to as shared private domains and are not the same as shared domains. See Shared Domains above.

When using private domains, you can have routes with the same hostname and domain name across different orgs and spaces. This cannot be done with shared domains.

Private domains can be HTTP or HTTPS only. TCP Routing is supported for shared domains only.

Create a private domain

Org managers can create a private domain with the following command:

  • cf CLI v7 
    $ cf create-private-domain my-org private-domain.example.com
  • cf CLI v6 
    $ cf create-domain my-org private-domain.example.com

Org managers can create a private domain for a subdomain with the following command:

  • cf CLI v7 
    $ cf create-private-domain my-org foo.private-domain.example.com
  • cf CLI v6 
    $ cf create-domain my-org foo.private-domain.example.com

Sharing a private domain with one or more orgs

Org managers can grant or revoke access to a private domain to other orgs if they have permissions for these orgs with the following commands:

$ cf share-private-domain test-org private-domain.example.com

$ cf unshare-private-domain test-org private-domain.example.com

Note that, as of cf CLI v7, cf unshare-private-domain provides a warning and requires confirmation before proceeding. The optional -f flag forces unsharing without confirmation.

Delete a private domain

Org managers can delete a domain from TAS for VMs with the cf delete-private-domain command:

  • cf CLI v7:

    $ cf delete-private-domain private-domain.example.com

    Important cf CLI v7 renames the delete-domain command to delete-private-domain.

  • cf CLI v6:

    $ cf delete-domain private-domain.example.com

Requirements for parent and child domains

In the domain myapp.shared-domain.example.com, shared-domain.example.com is the parent domain of subdomain myapp. Note the following requirements for domains:

  • You can only create a private domain that is parent to a private subdomain.
  • You can create a shared domain that is parent to either a shared or a private subdomain.

The domain foo.myapp.shared-domain.example.com is the child subdomain of myapp.shared-domain.example.com. Note the following requirements for subdomains:

  • You can create a private subdomain for a private parent domain only if the domains belong to the same org.
  • You can create a private subdomain for a shared parent domain.
  • You can only create a shared subdomain for a shared parent domain.
  • You cannot create a shared subdomain for a private parent domain.

DNS for domains

To create customized access to your apps, you can map specific or wildcard custom domains to TAS for VMs by using your DNS provider.

Mapping domains to your custom domain

To associate a registered domain name with a domain on TAS for VMs, configure a CNAME record with your DNS provider, pointing at any shared domain offered in TAS for VMs.

Mapping a single domain to your custom domain

To map a single domain to a custom domain to TAS for VMs, configure a CNAME record with your DNS provider.

The following table provides some example CNAME record mappings.

Record Set in Custom Domain Type Target in TAS for VMs
myapp.yourcustomdomain.com. CNAME myapp.shared-domain.example.com
www.yourcustomdomain.com. CNAME myapp.shared-domain.example.com

After you create the CNAME mapping, your DNS provider routes your custom domain to example-app.shared-domain.example.com. See your DNS provider documentation to determine whether the trailing . is required.

Mapping multiple subdomains to your custom domain

Use a wildcard CNAME record to point all of the subdomains in your custom domain to shared-domain.example.com.

Each separately configured subdomain has priority over the wildcard configuration.

The following table provides some example wildcard CNAME record mappings.

Record Set in Custom Domain Type Target in TAS for VMs
*.yourcustomdomain.com. CNAME *.shared-domain.example.com
*.yourcustomdomain.com. CNAME *.myapp.shared-domain.example.com

If you use a wildcard as the subdomain name, then your DNS provider can route from *.YOURCUSTOMDOMAIN to any of the following:

  • *.shared-domain.example.com
  • foo.myapp.shared-domain.example.com
  • bar.foo.myapp.shared-domain.example.com

Configuring DNS for your registered root domain

To use your root domain (for example, example.com) for apps on TAS for VMs you can either use custom DNS record types like ALIAS and ANAME, if your DNS provider offers them, or subdomain redirection.

Note Root domains are also called zone apex domains.

If your DNS provider supports using an ALIAS or ANAME record, configure your root domain with your DNS provider to point at a shared domain in TAS for VMs.

Record Name Target Note
ALIAS or ANAME empty or @ private-domain.example.com. Refer to your DNS provider documentation to determine whether to use an empty or @ value for the Name entry.

If your DNS provider does not support ANAME or ALIAS records you can use subdomain redirection, also known as domain forwarding, to redirect requests for your root domain to a subdomain configured as a CNAME. If you use domain forwarding, SSL requests to the root domain may fail if the SSL certificate only matches the subdomain. For more information about SSL certificates, see the Cloud Foundry documentation.

Configure the root domain to point at a subdomain such as www, and configure the subdomain as a CNAME record pointing at a shared domain in TAS for VMs.

Record Name Target Note
URL or Forward private-domain.example.com www.private-domain.example.com This method results in a 301 permanent redirect to the subdomain you configure.
CNAME www myapp.shared-domain.example.com
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