# Go Cloud Development Kit — Portable Cloud APIs for Go

> The Go Cloud Development Kit (Go CDK) by Google provides portable Go APIs for common cloud services like blob storage, databases, messaging, and secrets. It lets developers write cloud code once and deploy to AWS, GCP, Azure, or on-prem without vendor lock-in.

## Install

Save in your project root:

# Go Cloud Development Kit — Portable Cloud APIs for Go

## Quick Use
```bash
go get gocloud.dev

# Use portable blob storage
import "gocloud.dev/blob"
import _ "gocloud.dev/blob/s3blob"  // AWS S3
// or
import _ "gocloud.dev/blob/gcsblob" // GCP Cloud Storage
```

## Introduction
The Go Cloud Development Kit (Go CDK) is an open-source library by Google that provides a set of portable, idiomatic Go packages for accessing common cloud services. Rather than importing provider-specific SDKs, developers write against a single API and swap the backing service through URL-based configuration. This eliminates vendor lock-in and makes multi-cloud or hybrid deployments straightforward.

## What Go CDK Does
- Provides a unified blob storage API compatible with S3, GCS, Azure Blob, and local filesystem
- Offers portable pub/sub messaging across AWS SNS/SQS, GCP Pub/Sub, Azure Service Bus, and NATS
- Abstracts document and SQL database access with pluggable drivers
- Manages secrets and configuration through a portable secrets API supporting KMS, Vault, and local keys
- Enables URL-based service construction for runtime configuration without code changes

## Architecture Overview
Go CDK follows a driver-provider pattern. Each package (blob, pubsub, docstore, secrets) defines a portable API and a driver interface. Provider-specific implementations register themselves via blank imports. Services are opened using URLs like `s3://bucket-name` or `gs://bucket-name`, making it possible to change cloud providers through configuration alone. The library handles connection pooling, retries, and serialization internally.

## Self-Hosting & Configuration
- Install packages with `go get gocloud.dev` and import the desired portable APIs
- Register cloud providers via blank imports (e.g., `_ "gocloud.dev/blob/s3blob"`)
- Open resources using URL strings: `blob.OpenBucket(ctx, "s3://my-bucket?region=us-east-1")`
- Use environment variables or the standard AWS/GCP credential chains for authentication
- Run against local emulators or file-based backends during development

## Key Features
- Single API surface for blob, pubsub, docstore, secrets, and server infrastructure
- URL-based resource construction enables configuration-driven cloud provider selection
- Full support for AWS, GCP, Azure, and local/on-prem backends
- Idiomatic Go interfaces with context support, iterators, and error handling
- Maintained by Google with contributions from the Go community

## Comparison with Similar Tools
- **AWS SDK for Go** — Provider-specific; Go CDK abstracts across multiple clouds
- **Pulumi/Terraform** — Infrastructure provisioning tools; Go CDK is a runtime library for application code
- **Dapr** — Sidecar-based runtime abstraction; Go CDK is an in-process Go library with no sidecar
- **Apache Libcloud** — Python multi-cloud library; Go CDK serves the same role for the Go ecosystem
- **CloudEvents SDK** — Focused on event format standardization; Go CDK covers broader cloud service abstraction

## FAQ
**Q: Does Go CDK support all cloud services?**
A: Go CDK focuses on the most common portable services: blob storage, pub/sub, document stores, SQL databases, and secrets. It does not wrap every cloud-specific API.

**Q: Can I use Go CDK with on-premise infrastructure?**
A: Yes. Drivers exist for local filesystem (blob), in-memory (pubsub), HashiCorp Vault (secrets), and other self-hosted backends.

**Q: How does URL-based opening work?**
A: Register a driver via blank import, then call `blob.OpenBucket(ctx, "s3://bucket")`. The URL scheme selects the driver at runtime.

**Q: Is Go CDK production-ready?**
A: Yes. The core APIs (blob, pubsub, docstore) are stable and used in production by Google and other organizations.

## Sources
- https://github.com/google/go-cloud
- https://gocloud.dev/

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