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 makes the following matches for the two routes example-app.shared-domain.example.com and example-app.shared-domain.example.com/products:

Request Matched Route
http://example-app.shared-domain.example.com example-app.shared-domain.example.com
http://example-app.shared-domain.example.com/contact example-app.shared-domain.example.com
http://example-app.shared-domain.example.com/products example-app.shared-domain.example.com/products
http://example-app.shared-domain.example.com/products/123 example-app.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 example, products.shared-domain.example.com might 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. After the routing tier calculates a route as the best match for a request, it makes a load-balancing calculation using the configured balancing algorithm (by default, this is round-robin), 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 activates 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 created in or shared with the same space. For more information about sharing routes across spaces, see Share a route with another 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 versus 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 versus TCP shared domains.

HTTP routes include a domain, a host name (optional), and a context path (optional). shared-domain.example.com, example-app.shared-domain.example.com, and example-app.shared-domain.example.com/products are all examples of HTTP routes. Apps listen to the localhost port defined by the $PORT environment variable, which is 8080 on Diego. For example, requests to example-app.shared-domain.example.com are routed to the application container at localhost:8080.

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

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 TAS for VMs listens on. tcp.shared-domain.example.com:60000 is an example of a TCP route. Just as for HTTP routes, apps listen to the localhost port defined by the $PORT environment variable, which is 8080 on Diego. For example, requests to tcp.shared-domain.example.com:60000 are routed to the application container at localhost:8080.

When a port is reserved for a route, it cannot be reserved for another route. Host name 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 application 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 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 host name

In TAS for VMs, a host name 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 example-app.shared-domain.example.com by specifying the host name example-app with the cf create-route command as shown in this example:

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

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

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

  • http://example-app.shared-domain.example.com

  • https://example-app.shared-domain.example.com

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

Create an HTTP route without host name

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 host name with the cf create-route command:

$ cf create-route private-domain.example.com
Creating route private-domain.example.com for org example-org / space example-space as username@example.com...
OK

If DNS is 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 these 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, fail.

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

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

If DNS is 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 these URLs, such as http://foo.private-domain.example.com/foo

Create an HTTP route with wildcard host name

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 host name.

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

$ cf create-route foo.shared-domain.example.com --hostname '*'
Creating route *.foo.shared-domain.example.com for org example-org / space example-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 example-app.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 host name and domain to different apps.

A developer can create three routes using the same host name and domain in the space example-space by running:

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

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

The developer can then map the new routes to different apps by following the procedure 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, and then attempts to match host and domain.

Important
  • Routes with the same domain and host name 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

A developer can create a TCP route for tcp.shared-domain.example.com on an arbitrary port. This is the default in the v7 version of the cf CLI.

  • An arbitrary (random) port is the default. The --random port flag is not supported.

    $ cf create-route example-space tcp.shared-domain.example.com --random-port
Creating route tcp.shared-domain.example.com for org example-org / space example-space as user@example.com...
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 example-space tcp.shared-domain.example.com --port 60035
Creating route tcp.shared-domain.example.com:60035 for org example-org / space example-space as user@example.com...
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 host name, domain, port, and path.

$ cf routes
Getting routes as user@private-domain.example.com ...

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

Developers can only see routes in spaces where they are a member. Note that cf CLI v7 removes the port and path columns from the output.

View a route

Developers can view a route and its destinations within the current space with the cf route command. A route is uniquely identified by the combination of a host name, domain, port, and path. Note that the cf route command is available in cf CLI v8 only.

$ cf route shared-domain.example.com --hostname example-app
Showing route example-app.shared-domain.example.com in org o / space example-space as admin...

domain:     shared-domain.example.com
host:       example-app
port:
path:
protocol:   http

Destinations:
        app      process   port   protocol
        mystore  web       8080   http1

Developers can only view a route within a space where they are a member.

Check routes

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

To find out if a route with the host name store and the domain shared-domain.example.com and the path products exists, run:

$ cf check-route shared-domain.example.com --hostname store --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 mapped to port 443.

You can create and reserve routes for later use by following the procedure in Manually map a route. You can also map routes to their app immediately as part of a push. See Map a route with app push.

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

Manually map a route

For these 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 routes in the table to their respective apps. Developers use host name, domain, and path to uniquely identify a route to which to map their apps.

$ 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

Map a route with app push

Developers can map a route to their app with the cf push command. As of cf CLI v7, the best way to do this is by using the routes property in the manifest.

$ cf push example-app

To customize the route during push, specify the domain using the -d flag and the host name with the --hostname flag. The following command creates the foo.private-domain.example.com route for example-app:

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

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 procedure in Create a TCP route with a port.

$ cf push tcp-app -d 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 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 activates blue-green deployment. For more information see Using blue-green deployment to reduce downtime and risk.

Routing multiple apps to the same route might 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 Routing conflict in Troubleshooting app deployment and health.

Map multiple routes to one app

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

These routes are valid for a single app:

Route 1 Route 2
example-app.example.com example-app.apps.cf.example.com
example-app.example.com/foo example-app.apps.cf.example.com/foo

These routes are not valid for a single app:

Route 1 Route 2
example-app.example.com/foo example-app.apps.cf.example.com/bar
example-app.apps.cf.example.com/foo example-app.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. After it is mapped, this route becomes available to all other apps on the platform.

This example creates a foo.apps.internal internal route for example-app:

$ cf map-route example-app 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 host name, domain, and path:

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

Share a route with another space

To follow the procedure in this section, you must use cf CLI v8.5.0 or later. To download cf CLI v8.5.0 or later, see the Cloud Foundry CLI repository on GitHub.

You can share a route with another space using the cf share-route command. To move an app to another space, you can share routes with that space to prevent downtime during the transition. Rather than deleting the route in the original space and re-creating the route in the new space, you can share the route with the new space and map it to the app running in that space.

To share a route with another space:

  1. In a terminal window, allow route sharing by running:

    cf enable-feature-flag route_sharing

  2. Run:

    cf share-route DOMAIN --hostname HOSTNAME --path PATH -s SPACE -o ORG

    Where:

    • DOMAIN is the domain in the route for your app.
    • HOSTNAME is the host name in the route for your app.
    • PATH is the path in the route for your app.
    • SPACE is the space with which you want to share the route for your app.
    • ORG is the org containing space with which you want to share the route for your app. If the space with which you want to share the route is within the same org as the space that contains the route, do not include the -o flag.

    The following example command shares the route example-app.example.com/example-path with the other-space space in the other-org org:

    cf share-route example.com --hostname example-app --path example-path -s other-space -o other-org

Transfer ownership of a route to another space

Important To follow the procedure in this section, you must use cf CLI v8.5.0 or later. To download cf CLI v8.5.0 or later, see the Cloud Foundry CLI repository on GitHub.

After sharing a route with another space, you can transfer ownership of the route to that space using the cf move-route command. You can use this command if you are unable to maintain or delete a shared route within the space with which it was shared. For information about sharing routes across spaces, see Share a route with another space.

To move a route:

  1. In a terminal window, target the space from which the route was originally shared by running:

    cf target -s SPACE -o ORG

    Where:

    • SPACE is the space from which the route was originally shared.
    • ORG is the org containing space from which the route was originally shared. If the space from which the route was originally shared is within the same org as the space with which the route was shared, do not include the -o flag.

  2. Run:

    cf move-route DOMAIN --hostname HOSTNAME --path PATH -s SPACE -o ORG

    Where:

    • DOMAIN is the domain in the route for your app.
    • HOSTNAME is the host name in the route for your app.
    • PATH is the path in the route for your app.
    • SPACE is the space to which you want to move the route for your app.
    • ORG is the org containing space to which you want to move the route for your app. If the space to which you want to move the route is within the same org as the space that contains the route, do not include the -o flag.

    The following example command moves the route example-app.example.com/example-path with the other-space space in the other-org org:

    cf move-route example.com --hostname example-app --path example-path -s other-space -o other-org

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 host name, domain, and path:

$ cf delete-route private-domain.example.com --hostname example-app --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 available only 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 example-app --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 example-app

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

$ curl example-app.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.

These are 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 no instance is 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 ('example-route.cf.com')

Domains

The term domain here 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 refers 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 VMsrouters. 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 example-org as user@example.com... 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 versus TCP domains

By default, TAS for VMs only supports routing of HTTP requests to apps. 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 host names, 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. Only shared domains can use a TCP protocol.

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 might offer developers the choice of creating routes for their apps from shared-domain.example.com and cf.example-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. For more information, see Routes.

When using shared domains, you cannot have routes with the same host name 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 activate service discovery, the internal domain apps.internal becomes available for route mapping.

Admins can configure multiple internal domains. 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 called as shared private domains and are not the same as shared domains. For more information, see Shared domains.

When using private domains, you can have routes with the same host name 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 by running:

$ cf create-private-domain example-org private-domain.example.com

Org managers can create a private domain for a subdomain by running:

$ cf create-private-domain example-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. As of cf CLI v7, cf unshare-private-domain command provides a warning and requires confirmation before it proceeds.

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

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

Delete a private domain

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

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

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

Requirements for parent and child domains

In the domain example-app.shared-domain.example.com, shared-domain.example.com is the parent domain of subdomain example-app. The following list describes requirements for creating 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.example-app.shared-domain.example.com is the child subdomain of example-app.shared-domain.example.com. The following list describes requirements for creating 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.

Here are some example CNAME record mappings.

Record set in custom domain Type Target in TAS for VMs
example-app.yourcustomdomain.com. CNAME example-app.shared-domain.example.com
www.yourcustomdomain.com. CNAME example-app.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 find out if 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.

Here are 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 *.example-app.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.example-app.shared-domain.example.com
  • bar.foo.example-app.shared-domain.example.com

Configuring DNS for your registered root domain

To use your root domain for apps on TAS for VMs, you can use custom DNS record types like ALIAS and ANAME, if your DNS provider offers them, or you can use 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. To decide whether to use an empty or @ value for the Name entry, see the documentation for your DNS provider.

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.

Important If you use domain forwarding, SSL requests to the root domain might fail if the SSL certificate matches only 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 causes a 301 permanent redirect to the subdomain you configure.
CNAME www example-app.shared-domain.example.com
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