☁️ GCP Terraform Generator

This module provides a Cloudhopper generator for deploying annotated Java functions as Google Cloud Functions (HTTP-triggered) using Terraform.

It is used by the Cloudhopper annotation processor to generate:

GCP-specific Java handler classes
Terraform infrastructure resources
Supporting metadata for integration and deployment

📦 How to Use

To use this generator in your own project, follow these steps:

1. Add the Maven dependency

<dependency>
  <groupId>eu.cloudhopper.mc</groupId>
  <artifactId>generator-gcp-terraform</artifactId>
  <version>${cloudhopper.version}</version>
</dependency>

2. Configure the annotation processor

<plugin>
  <artifactId>maven-compiler-plugin</artifactId>
  <version>3.8.1</version>
  <configuration>
    <source>21</source>
    <target>21</target>
    <encoding>UTF-8</encoding>
    <annotationProcessors>
      <annotationProcessor>
        eu.cloudhopper.mc.deployment.config.generator.ServerlessFunctionProcessor
      </annotationProcessor>
    </annotationProcessors>
    <compilerArgs>
      <arg>-Acloudprovider=gcp</arg>
      <arg>-AgeneratorId=gcp-terraform</arg>
      <arg>-AconfigOutputDir=${project.build.directory}/deployment/gcp-terraform</arg>
      <arg>-AtargetDir=${project.build.directory}</arg>
      <arg>-AartifactId=${project.artifactId}</arg>
      <arg>-Aversion=${project.version}</arg>
      <arg>-Aclassifier=gcp</arg>
    </compilerArgs>
  </configuration>
</plugin>

This configuration ensures that the correct templates are applied and the output is structured for GCP.

📁 Templates

Templates for this generator are located at:

src/main/resources/templates/gcp-terraform/

Template	Output Type	Description
`shared.ftl`	Terraform	Generates shared resources (provider blocks, logging)
`handler.ftl`	Java	Generates the Java wrapper for the handler
`function.ftl`	Terraform	Generates the Terraform registration for the handler
`apiIntegrationClass.ftl`	Java	Generates an APIFunction
`apiIntegration.ftl`	JSON	Generates an OpenAPI 2.0 snippet
`apiRegistration.ftl`	Terraform	Generates a Terraform function registration
`schedule.ftl`	Terraform	Generates a `google_cloud_scheduler_job` resource
`api.ftl`	Terraform	Generates a `google_api_gateway_api` resource

ℹ️ The doc/ folder in the template path is not used during generation. It may contain examples or template prototypes.

🔌 Template Registration

This generator registers itself using:

@TemplateRegistration(
    generatorId = "gcp-terraform",
    templates = {
        @Template(phase = GenerationPhase.SHARED,    templateName = "shared.ftl",              outputFileExtension = "tf",   outputSubDirectory = "",            javaFile = false),
        @Template(phase = GenerationPhase.FUNCTION,  templateName = "handler.ftl",             outputFileExtension = "java", outputSubDirectory = "generated",   javaFile = true),
        @Template(phase = GenerationPhase.FUNCTION,  templateName = "function.ftl",            outputFileExtension = "tf",   outputSubDirectory = "",            javaFile = false),
        @Template(phase = GenerationPhase.API,       templateName = "apiIntegrationClass.ftl", outputFileExtension = "java", outputSubDirectory = "",            javaFile = true),
        @Template(phase = GenerationPhase.API,       templateName = "apiIntegration.ftl",      outputFileExtension = "json", outputSubDirectory = "api-routes/", javaFile = false),
        @Template(phase = GenerationPhase.API,       templateName = "apiRegistration.ftl",     outputFileExtension = "tf",   outputSubDirectory = "",            javaFile = false),
        @Template(phase = GenerationPhase.SCHEDULE,  templateName = "schedule.ftl",            outputFileExtension = "tf",   outputSubDirectory = "",            javaFile = false),
        @Template(phase = GenerationPhase.FINALIZE,  templateName = "api.ftl",                 outputFileExtension = "tf",   outputSubDirectory = "",            javaFile = false)
    }
)
public class GcpTerraformJava21TemplateRegistration { ... }

@Template uses templateName (the .ftl file), phase (one of FUNCTION, API, SCHEDULE, FINALIZE, SHARED), outputFileExtension, optional outputSubDirectory, and javaFile.

This registration is auto-discovered using Java’s SPI (META-INF/services/...) mechanism.

📂 Output

Artifact	Location
Java handler classes	`target/generated-sources/gcp-terraform/`
Terraform configuration	`target/deployment/gcp-terraform/*.tf`
Deployment metadata	`target/classes/META-INF/cloudhopper/`
Optional ZIP for deployment	`target/${artifactId}-${version}-gcp.zip`

🧩 What’s Special About GCP

Handler Generation: The generator produces a Java class that implements com.google.cloud.functions.HttpFunction.
Context Mapping: The handler uses GcpCloudFunctionRequestHandler, which adapts GCP’s request/response and environment into Cloudhopper's CloudRequestHandler interface.
Terraform Output: The generated .tf files define the Cloud Function, IAM permissions, and optional API Gateway or scheduler bindings.

Module	Description
`provider-gcp`	Contains `GcpCloudFunctionRequestHandler` used by handlers
`deployment-config-api`	Defines annotations and runtime interfaces

📝 Use this generator to compile and deploy Cloudhopper functions as Google Cloud Functions using Terraform.

📦 How to Use​

1. Add the Maven dependency​

2. Configure the annotation processor​

📁 Templates​

🔌 Template Registration​

📂 Output​

🧩 What’s Special About GCP​

📚 Related Modules​