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Set up integration with Service Directory

This guide assumes that you have a running Traffic Director deployment and that you registered at least one service with Service Directory. The setup instructions apply whether you are using Envoy or proxyless gRPC.

To use Service Directory and Traffic Director, the first step is to publish your service to Service Directory. See information about publishing a service to Service Directory or the Service Directory documentation for general overview information.

After the service is registered with Service Directory, you create a service binding by using Traffic Director's API resources. You create a backend service that is dedicated to the integration with Service Directory, because a backend service that references service bindings cannot have backends or an associated health check.

Traffic Director forwarding rule and host rule requirements

When you configure Traffic Director for use with Service Directory, follow these guidelines:

  1. Ensure that the Traffic Director forwarding rule uses the 0.0.0.0 virtual IP address (VIP).
  2. If you have a private zone, make sure that the host rule in the URL map matches the DNS name that Service Directory configures in your Cloud DNS private zone.

If you do not follow these guidelines, outbound requests from your applications are likely to fail.

Set the network-services API endpoint

Before you create and use a backend service, make sure that the network-services API endpoint is set so that service bindings resources under network-services resources are referenced correctly. Set the network-services API endpoint using the following command.

export CLOUDSDK_API_ENDPOINT_OVERRIDES_NETWORKSERVICES="https://networkservices.googleapis.com/"

Role and permission requirements

Make sure that you have following permissions and roles before you create your Traffic Director deployment.

Service binding permissions and roles

This section does not discuss project-level Owner, Editor, and Viewer permissions. It describes the permissions and roles required to create, read, update, and delete resources.

Action Permission Roles
Create a service binding. networkservices.serviceBindings.create Network Admin
Get a service binding. networkservices.serviceBindings.get Network Admin, Network Viewer
List service bindings in a Google Cloud project. networkservices.serviceBindings.list Network Admin, Network Viewer
Update service bindings. networkservices.serviceBindings.update Network Admin
Delete service bindings. networkservices.serviceBindings.delete Network Admin

Service Directory service permissions

The Service Directory administrator must grant the permission servicedirectory.services.bind to the service account that is attempting to attach the service binding to the Service Directory service. This lets the service account use a Service Directory service, meaning that the account can reference a Service Directory service in a service binding.

Permissions enforcement

IAM permission checks are performed when you configure Traffic Director. You must have the requisite permissions to create service bindings, and to associate service bindings with particular Service Directory services. If the correct permissions are in place, you can configure your mesh clients to learn about and send traffic to a Service Directory service.

Because these checks happen at configuration time, removing the bind permission on an existing Service Directory service does not disrupt traffic flows. After a service binding is established, removing a permission does not affect whether a mesh client can learn about and send traffic to a Service Directory service.

To stop a mesh client from communicating with a Service Directory service, you can use other mechanisms:

  1. Restrict access to the Service Directory service. For example, you can use firewall rules or a Traffic Director authorization policy).
  2. Delete the Service Directory service.
  3. Update your Traffic Director configuration, for example, by removing the service binding from the backend service.

Best practices

  • Although Service Directory allows registration of endpoints using the Service Directory API, we recommend using integrations that automatically register to Service Directory when they are available. For more information on these integrations, see Service Directory for GKE overview and Service Directory and Cloud Load Balancing overview.
  • We recommend that you use the same namespace and service for a particular logical service, even when that service is deployed across different regions.

Use Service Directory for service discovery

The following diagram provides an overview of the end state of this setup procedure, including configuration, how different systems interact, and how a request is resolved to a service's endpoints. This example assumes that you already have a service registered with Service Directory.

Configuration details for using Service Directory for service discovery.
Configuration details for using Service Directory for service discovery (click to enlarge)

Making a Service Directory service available to Traffic Director consists of the following steps.

  1. Create a new backend service in Traffic Director and do not create backends for the backend service.
  2. Create a global service binding for the Service Directory service.
  3. Bind the Service Directory service to this backend service. Optionally, set additional fields and policies on the backend service.

  4. Create a new routing configuration, or update an existing configuration, so that client requests can be routed to the new backend service.

You cannot set a health check on a backend service that references a service binding. The backend service also cannot have backends.

Create the integration

Use the following instructions to integrate Traffic Director with Service Directory.

Create a backend service

Use the following instructions to create a backend service in your Traffic Director deployment.

  1. Create a backend service to use with Service Directory services.

    gcloud compute backend-services create td-sd-demo-service \
     --global \
     --load-balancing-scheme=INTERNAL_SELF_MANAGED
    
  2. Create a service binding that references a Service Directory service.

    gcloud beta network-services service-bindings create my-sd-binding \
     --location global \
     --service-directory-region us-east1 \
     --service-directory-namespace my-namespace \
     --service-directory-service my-service
    
  3. Bind the service to the backend service.

    gcloud beta compute backend-services update td-sd-demo-service \
     --global \
     --service-bindings my-sd-binding
    

After you create the backend service and bind one or more Service Directory services, Traffic Director begins to track the endpoints that are associated with the Service Directory service. The endpoints are distinct IP:port pairs. To make this service routable, you need to configure routing.

Configure routing

The following example assumes that you already have a basic routing configuration, including a URL map that is called my-url-map.

  • First, you create a path matcher for this URL map. The path matcher is uncomplicated. When it's used, it resolves to td-sd-demo-service, which you created in the previous step.
  • Next, you add a host rule to the URL map. This host rule causes the path matcher to be used if a request specifies the hostname myservice.example.com.
  1. Create a simple path matcher that points to your backend service.

    gcloud compute url-maps add-path-matcher my-url-map \
     --global \
     --default-service td-sd-demo-service \
     --path-matcher-name my-path-matcher
    
  2. Map the backend service to a new host rule in the existing URL map.

    gcloud compute url-maps add-host-rule my-url-map \
     --global \
     --path-matcher-name=my-path-matcher \
     --hosts=myservice.example.com
    

Attach the same service from multiple regions

Traffic Director lets you bind multiple Service Directory services to the same backend service. For instance, you might have two Service Directory services, each identical, but with endpoints in different Google Cloud regions or zones. In other words, a single global backend service could have two global service bindings, with one pointing to a service in us-east1 and the other pointing to a service in us-west1.

  1. Create a backend service for your imported Service Directory service.

    gcloud compute backend-services create td-sd-demo-service \
     --global \
     --load-balancing-scheme=INTERNAL_SELF_MANAGED
    
  2. Create a service binding to Service Directory service in us-east1.

    gcloud beta network-services service-bindings create us-east1-binding \
     --location global \
     --service-directory-region us-east1 \
     --service-directory-namespace my-namespace \
     --service-directory-service my-service \
    
  3. Create a service binding to Service Directory service in us-west1.

    gcloud beta network-services service-bindings create us-west1-binding \
     --location global
     --service-directory-region us-west1 \
     --service-directory-namespace my-namespace \
     --service-directory-service my-service \
    
  4. Bind the us-east1 and the us-west1 services to the backend service.

    gcloud compute backend-services update td-sd-demo-service \
      --global \
      --service-bindings us-east1-binding,us-west1-binding
    

Apply advanced traffic management policies

In the preceding section, you used Traffic Director to set up routing policies against an existing Service Directory service. You can apply this pattern to more advanced traffic management scenarios.

Consider this scenario. You have an existing canary service that is outside of the Traffic Director mesh. The canary service is a backend for an internal HTTP(S) load balancer. You want to replay some production traffic originating in the Traffic Director mesh to this external service. Traffic Director can do this using RequestMirrorPolicy, which can send traffic to another backend service when the request is processed. This process is also called shadowing a request, and it lets you examine traffic without affecting your production services.

You can enable Envoy clients to shadow traffic to a canary service by manually adding or removing the canary service endpoint to the Traffic Director mesh. However, the process is simpler when you use the Service Directory integration.

Using Service Directory for service discovery with mirroring.
Using Service Directory for service discovery with mirroring(click to enlarge)

In this example, you start by pointing a backend service to the Service Directory registration for the payments canary service. Then you add a request mirror policy to the service in Traffic Director.

  1. Create a backend service for the request mirror policy.

    gcloud compute backend-services create payments-canary-bes \
     --global \
     --load-balancing-scheme=INTERNAL_SELF_MANAGED
    
  2. Create a service binding that references a Service Directory service.

    gcloud beta network-services service-bindings create my-sd-binding \
     --location global \
     --service-directory-region us-east1 \
     --service-directory-namespace my-namespace \
     --service-directory-service my-service \
    
  3. Bind the Service Directory service to the canary backend service.

    gcloud beta compute backend-services update payments-canary-bes \
     --global \
     --service-bindings my-sd-binding
    
  4. Edit the URL map to mirror requests to the canary service.

    gcloud compute url-maps edit my-url-map \
      --region=global
    
  5. After the URL map configuration is loaded into an editor, add the request mirror policy to mirror requests to the existing Service Directory service.

    defaultService: my-project/global/default-service
       hostRules:
        - hosts:
          - '*'
          pathMatcher: path-matcher-one
       pathMatchers:
        - defaultService: my-project/global/default-service
         name: path-matcher-one
         pathRules:
          - paths:
            - /payments/
            service: my-project/global/default-service
            requestMirrorPolicy:
              backendService: myproject/global/payments-canary-bes
    

Remove a service binding from a backend service

To remove a service binding from the backend service, pass a new list of service bindings to the gcloud compute backend-services update command. The new list must not include the service binding that you want to delete:

  • To remove all service bindings, set the --no-service-bindings flag.
  • To remove one or more service bindings: pass a new list of service bindings that omits the service bindings that you want to remove to the --service-bindings flag.

Add or remove service bindings

The bind-service command adds a service binding to the set of existing service bindings on the backend service.

gcloud compute backend-services bind-service BACKEND_SERVICE_NAME \
  --service-binding-name SERVICE_BINDING_URL \
  --global

The unbind-service command removes a service binding from the set of existing service bindings on the backend service.

gcloud compute backend-services unbind-service BACKEND_SERVICE_NAME \
  --service-binding-name SERVICE_BINDING_URL \
  --global

The commands bind-service and unbind-service are gcloud constructs. They are not API-level constructs.

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