Configuring Container-to-Container Networking

This topic describes how to configure the Container-to-Container Networking feature, which allows direct network traffic between apps. For an overview of how Container-to-Container Networking works, see the Container-to-Container Networking topic.

Create and Manage Networking Policies

This section describes how to create and modify Container-to-Container Networking policies using the Cloud Foundry Command Line Interface (cf CLI).

Note: With the NSX-T integration, container networking policies and ASGs continue to work as normal. Advanced ASG logging is not supported with NSX-T.

Prerequisites

  • Ensure that you are using cf CLI v6.42 or later:
    $ cf version
    
    For more information about updating the cf CLI, see the Installing the cf CLI topic.

Prerequisite

To use the plugin, you must have the network.write UAA scope. This scope gives you the right to create a policy between any two apps in spaces for which you are a Space Developer. If you do not have this scope, you must request it by opening a support ticket with PWS.

Add a Network Policy

To add a policy that allows direct network traffic from one app to another, run the following command:

cf add-network-policy SOURCE_APP --destination-app DESTINATION_APP -s DESTINATION_SPACE_NAME -o DESTINATION_ORG_NAME --protocol (tcp | udp) --port RANGE

Replace the placeholders in the above command as follows:

  • SOURCE_APP is the name of the app that sends traffic.
  • DESTINATION_APP is the name of the app that will receive traffic.
  • DESTINATION_SPACE_NAME is the space of the destination app. The default is the targeted space.
  • DESTINATION_ORG_NAME is the org of the destination app. The default is the targeted org.
  • PROTOCOL is one of the following: tcp or udp.
  • RANGE are the ports at which to connect to the destination app. The allowed range is from 1 to 65535. You can specify a single port, such as 8080, or a range of ports, such as 8080-8090.

The following example command allows access from the frontend app to the backend app over TCP at port 8080:

$ cf add-network-policy frontend --destination-app backend --protocol tcp --port 8080
Adding network policy to app frontend in org my-org / space dev as admin...
OK

List Policies

You can list all the policies in your space, or just the policies for which a single app is the source:

  • To list the all the policies in your space, run cf network-policies.

    $ cf network-policies
    
  • To list the policies for an app, run cf network-policies --source MY-APP. Replace MY-APP with the name of your app.

    $ cf network-policies --source example-app
    

    The following example command lists policies for the app frontend:

    $ cf network-policies --source frontend
    Listing network policies in org my-org / space dev as admin...
    
    source      destination   protocol   ports    destination space    destination org
    frontend    backend       tcp        8080     example-space        example-org
    

Remove a Network Policy

To remove a policy that allows direct network traffic from an app, run the following command:

cf remove-network-policy SOURCE_APP --destination-app DESTINATION_APP -s DESTINATION_SPACE_NAME -o DESTINATION_ORG_NAME --protocol PROTOCOL --port RANGE

Replace the placeholders in the above command to match an existing policy, as follows:

  • SOURCE_APP is the name of the app that sends traffic.
  • DESTINATION_APP is the name of the app that receives traffic.
  • DESTINATION_SPACE_NAME is the space of the destination app. The default is the targeted space.
  • DESTINATION_ORG_NAME is the org of the destination app. The default is the targeted org.
  • PROTOCOL is either tcp or udp.
  • PORTS are the ports connecting the apps. The allowed range is from 1 to 65535. You can specify a single port, such as 8080, or a range of ports, such as 8080-8090.

The following command deletes the policy that allowed the frontend app to communicate with the backend app over TCP on port 8080:

$ cf remove-network-policy frontend --destination-app backend --protocol tcp --port 8080
Removing network policy to app frontend in org my-org / space dev as admin...
OK

Disable Network Policy Enforcement

You can disable Silk network policy enforcement between apps. Disabling network policy enforcement allows all apps to send network traffic to all other apps in the foundation despite no policy specifically allowing it.

To disable network policy enforcement between apps, do the following:

  1. Go to the Networking pane of your PAS tile.

  2. Disable the Enable Silk Network Policy Enforcement checkbox.

  3. Click Save.

App Service Discovery

With app service discovery, apps pushed to Pivotal Web Services (PWS) can establish container-to-container communications through a known route served by internal BOSH DNS. This allows front end apps to easily connect with back end apps.

To establish container-to-container communications between a front end and back end app, a developer:

  1. Launches a back end app that publishes a local endpoint.
  2. Maps a named route to the endpoint.
  3. Creates a network policy that allows direct traffic from the front end to the back end app.
  4. Launches the front end app.

See Cats and Dogs with Service Discovery in GitHub for an example, written in Go, that demonstrates communication between front end and back end apps.