provider-gcp

This module contains the core utility class GcpCloudFunctionRequestHandler, used by Cloudhopper-based generators to execute cloud-neutral functions in Google Cloud Functions.

It is used internally by the generator-gcp-terraform module and is essential for developers writing custom GCP serverless generators.

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🧩 Purpose

The GcpCloudFunctionRequestHandler<I, O> class:

• Implements the HttpFunction interface required by Google Cloud Functions
• Deserializes JSON input using Gson
• Invokes a generic CloudRequestHandler<I, O>
• Serializes the output as a JSON HTTP response
• Adapts GCP-specific request metadata into Cloudhopper's HandlerContext

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🔧 Example Usage in a Generated Function

public class MyFunction extends GcpCloudFunctionRequestHandler<MyInput, MyOutput> {

    public MyFunction() {
        super(new MyCloudhopperFunction(), TypeToken.get(MyInput.class));
    }
}

Google Cloud Functions will call service(...) on this class, which in turn:

1. Parses the HTTP request body into a Java object
2. Passes it to your CloudRequestHandler
3. Serializes the result to the HTTP response

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🧠 Internal Structure

Method	Responsibility
service(...)	GCF entrypoint: parse, delegate, serialize
parseInput(...)	Uses Gson to deserialize JSON input
writeOutput(...)	Converts output to JSON and writes to response
GcpContextAdapter	Implements HandlerContext using GCF metadata (e.g. env vars and headers)

Some AWS/Azure-specific context features (ARN, logs, etc.) are not available on GCP and return null or -1.

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💡 For Generator Developers

If you are building your own GCP generator (or extending generator-gcp-terraform):

• Use GcpCloudFunctionRequestHandler as the base class for the generated function handler
• Provide:
  • A reference to your CloudRequestHandler-based function
  • A TypeToken<I> to support proper deserialization of generic input
• Ensure this class is included in the deployment JAR

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📦 Module Overview

Component	Purpose
GcpCloudFunctionRequestHandler	Generic HTTP adapter for Google Cloud Functions
GcpContextAdapter	Maps GCF environment and headers to Cloudhopper’s HandlerContext

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📚 Related Modules

Module	Description
generator-gcp-terraform	Uses this class to generate deployable GCP function handlers
deployment-config-api	Defines CloudRequestHandler and HandlerContext interfaces

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GcpCloudFunctionRequestHandler.java

public abstract class GcpCloudFunctionRequestHandler<I, O> implements HttpFunction {
    // ...
}

This class is the GCP-specific bridge between Cloudhopper’s cloud-agnostic logic and Google’s serverless infrastructure.