Each resource must extend the Resource class.

Naming a Resource

Each resource gets its name from a combination of the @Namespace and @Type annotations. The root package in each provider should have that is annotated with the @Namespace annotation. For example:


import gyro.core.Namespace;
import gyro.core.resource.DocNamespace;

Use the @Type(<string>) annotation on the resource implementation class to specify the resource name, for example:

public class VpcResource extends Resource {

When combined these annotations provide the name exposed to Gyro, aws::vpc, in this example.


Model a resource by looking at both the cloud providers web console and their API to see what properties a resource uses.

A general rule of thumb is to model a resource similar to the cloud provider’s API model and adjust based on how the API is exposed on the provider’s web console. In some instances the cloud provider’s web console will hide some of the complexity of the API and part of the modeling process is to determine if that abstraction should be kept.

As an example, a basic aws::vpc resource has a cidr block, dns settings, and tags. The model might look like the following:

public class VpcResource extends Resource {

    private String cidrBlock;
    private Boolean enableDnsHostnames;
    private Boolean enableDnsSupport;
    private Map<String, String> tags;

    public String getCidrBlock() {...}
    public void setCidrBlock(String cidrBlock) {...}


Each property will be exposed in the Gyro configuration language by converting the getter method from camel case to lowercase with dashes – getCidrBlock becomes cidr-block. Using the VpcResource resource above, in Gyro it would be configured as:

aws::vpc vpc
    cidr-block: ""
    enable-dns-hostnames: true

    tags: {
        Name: "Gyro VPC"


There are several annotations that should be used when modeling a resource. These annotations give Gyro extra information necessary when running the diff engine.


The property that is the unique identifier of the resource in the cloud should be annotated with @Id. This is used by Gyro to create placeholder objects when a user provides the id as a string value rather than as a reference to an existing resource.


Any property that is output only (i.e cannot be set by the user) should be annotated with @Output. This is currently only used by the documentation system.


By default properties are not considered updatable in Gyro. This means Gyro will attempt to replace a resource if a property changed. However, if the cloud provider API supports changing the property, add the @Updatable annotation to the getter method and Gyro will call the update(GyroUI ui, State state, Resource config, Set<String> changedProperties) method of the resource with the names of the properties that changed passed into changedProperties.