Understanding the benefits of references

You can use references to define the properties of your configuration or templates instead of directly providing values.

With references, you can access properties that are not defined until the resource is created. For example, when you define a virtual machine (VM) in your configuration, you do not know its IP address. However, you can create a reference to the IP address.

In this step, you will examine an updated two-vms.yaml that contains a network, as well as VM instances that reference the network.

Opening the new configuration

Open a new two-vms.yaml, which defines a network called a-new-network:

cd deploymentmanager-samples/examples/v2/step_by_step_guide/step4_use_references

nano two-vms.yaml  # use your preferred text editor

Viewing the references to the network

In the properties section of both your virtual machine instances, note that the value of network have a reference to the new network's selfLink property, so that the network interface property looks like this:

- network: $(ref.a-new-network.selfLink)

Deploying the configuration

In the sample, replace all instances of MY_PROJECT with your project ID, then deploy your configuration with the following command:

gcloud deployment-manager deployments create deployment-with-references --config two-vms.yaml

To view your deployment, use the following command:

gcloud deployment-manager deployments describe deployment-with-references

Looking ahead: templates and variables

To maximize efficiency when you're building complex configurations, follow best practices such as using variables and templates.

In the next step, you will learn about templates and how they enable flexible, dynamic configurations.

Deleting your deployment

Once again, we recommend that you delete the deployment to avoid charges. You don't need this deployment for the next step. Run the following command to delete the deployment:

gcloud deployment-manager deployments delete deployment-with-references