/README.md

# Go Micro [![Go.Dev reference](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/go-micro.dev/v5?tab=doc) [![Go Report Card](https://goreportcard.com/badge/github.com/go-micro/go-micro)](https://goreportcard.com/report/github.com/go-micro/go-micro) 

Go Micro is a framework for distributed systems development.

**[📖 Documentation](https://go-micro.dev/docs/)** | [Sponsored by Anthropic](https://go-micro.dev/blog/3)

## Overview

Go Micro provides the core requirements for distributed systems development including RPC and Event driven communication.
The Go Micro philosophy is sane defaults with a pluggable architecture. We provide defaults to get you started quickly
but everything can be easily swapped out.

## Features

Go Micro abstracts away the details of distributed systems. Here are the main features.

- **Authentication** - Auth is built in as a first class citizen. Authentication and authorization enable secure
  zero trust networking by providing every service an identity and certificates. This additionally includes rule
  based access control.

- **Dynamic Config** - Load and hot reload dynamic config from anywhere. The config interface provides a way to load application
  level config from any source such as env vars, file, etcd. You can merge the sources and even define fallbacks.

- **Data Storage** - A simple data store interface to read, write and delete records. It includes support for many storage backends
in the plugins repo. State and persistence becomes a core requirement beyond prototyping and Micro looks to build that into the framework.

- **Data Model** - A typed data model layer with CRUD operations, queries, and multiple backends (memory, SQLite, Postgres). Define Go
  structs with tags and get type-safe Create/Read/Update/Delete/List/Count operations. Accessible via `service.Model()` alongside
  `service.Client()` and `service.Server()` for a complete service experience: call services, handle requests, save and query data.

- **Service Discovery** - Automatic service registration and name resolution. Service discovery is at the core of micro service
  development. When service A needs to speak to service B it needs the location of that service. The default discovery mechanism is
  multicast DNS (mdns), a zeroconf system.

- **Load Balancing** - Client side load balancing built on service discovery. Once we have the addresses of any number of instances
  of a service we now need a way to decide which node to route to. We use random hashed load balancing to provide even distribution
  across the services and retry a different node if there's a problem.

- **Message Encoding** - Dynamic message encoding based on content-type. The client and server will use codecs along with content-type
  to seamlessly encode and decode Go types for you. Any variety of messages could be encoded and sent from different clients. The client
  and server handle this by default. This includes protobuf and json by default.

- **RPC Client/Server** - RPC based request/response with support for bidirectional streaming. We provide an abstraction for synchronous
  communication. A request made to a service will be automatically resolved, load balanced, dialled and streamed.

- **Async Messaging** - PubSub is built in as a first class citizen for asynchronous communication and event driven architectures.
  Event notifications are a core pattern in micro service development. The default messaging system is a HTTP event message broker.

- **MCP Integration** - An MCP gateway you can integrate as a library, server or CLI command which automatically exposes services
  as tools for agents or other AI applications. Every service/endpoint get's converted into a callable tool.

- **Multi-Service Binaries** - Run multiple services in a single process with isolated state per service. Start as a modular monolith,
  split into separate deployments when you need independent scaling. Each service gets its own server, client, and store while sharing
  the registry and broker for inter-service communication.

- **Pluggable Interfaces** - Go Micro makes use of Go interfaces for each distributed system abstraction. Because of this these interfaces
  are pluggable and allows Go Micro to be runtime agnostic. You can plugin any underlying technology.

## Getting Started

To make use of Go Micro 

```bash
go get go-micro.dev/v5@v5.16.0
```

Create a service and register a handler

```go
package main

import (
        "go-micro.dev/v5"
)

type Request struct {
        Name string `json:"name"`
}

type Response struct {
        Message string `json:"message"`
}

type Say struct{}

func (h *Say) Hello(ctx context.Context, req *Request, rsp *Response) error {
        rsp.Message = "Hello " + req.Name
        return nil
}

func main() {
        // create the service
        service := micro.New("helloworld")

        // register handler
        service.Handle(new(Say))

        // run the service
        service.Run()
}
```

Set a fixed address

```go
service := micro.New("helloworld", micro.Address(":8080"))
```

Call it via curl

```bash
curl -XPOST \
     -H 'Content-Type: application/json' \
     -H 'Micro-Endpoint: Say.Hello' \
     -d '{"name": "alice"}' \
      http://localhost:8080
```

## MCP & AI Agents

Go Micro is designed for an **agent-first** workflow. Every service you build automatically becomes a tool that AI agents can discover and use via the [Model Context Protocol (MCP)](https://modelcontextprotocol.io/).

- **[🤖 Agent Playground](https://go-micro.dev/docs/mcp.html)** — Chat with your services through an interactive AI agent at `/agent`
- **[🔧 MCP Tools Registry](https://go-micro.dev/docs/mcp.html)** — Browse all services exposed as AI-callable tools at `/api/mcp/tools`
- **[📖 MCP Documentation](https://go-micro.dev/docs/mcp.html)** — Full guide to MCP integration, auth, and scopes

### Services as Tools

Write a normal Go Micro service and it's instantly available as an MCP tool:

```go
// SayHello greets a person by name.
// @example {"name": "Alice"}
func (g *GreeterService) SayHello(ctx context.Context, req *HelloRequest, rsp *HelloResponse) error {
    rsp.Message = "Hello " + req.Name
    return nil
}
```

Run with `micro run` and the agent playground and MCP tools registry are ready:

```bash
micro run
# Agent Playground:  http://localhost:8080/agent
# MCP Tools:         http://localhost:8080/api/mcp/tools
```

Use `micro mcp serve` for local AI tools like Claude Code, or connect any MCP-compatible agent to the HTTP endpoint.

See the [MCP guide](https://go-micro.dev/docs/mcp.html) for authentication, scopes, and advanced usage.

## Multi-Service Binaries

Run multiple services in a single binary — start as a modular monolith, split into separate deployments later when you actually need to.

```go
users := micro.New("users", micro.Address(":9001"))
orders := micro.New("orders", micro.Address(":9002"))

users.Handle(new(Users))
orders.Handle(new(Orders))

// Run all services together with shared lifecycle
g := micro.NewGroup(users, orders)
g.Run()
```

Each service gets its own server, client, store, and cache while sharing the registry, broker, and transport — so they can discover and call each other within the same process.

See the [multi-service example](examples/multi-service/) for a working demo.

## Data Model

Go Micro includes a typed data model layer for persistence. Define a struct, tag a key field, and get type-safe CRUD and query operations backed by memory, SQLite, or Postgres.

```go
import (
        "go-micro.dev/v5/model"
        "go-micro.dev/v5/model/sqlite"
)

// Define your data type
type User struct {
        ID    string `json:"id" model:"key"`
        Name  string `json:"name"`
        Email string `json:"email" model:"index"`
        Age   int    `json:"age"`
}
```

Register your types and use the model:

```go
service := micro.New("users")

// Register and use the service's model backend
db := service.Model()
db.Register(&User{})

// CRUD operations
db.Create(ctx, &User{ID: "1", Name: "Alice", Email: "alice@example.com", Age: 30})

user := &User{}
db.Read(ctx, "1", user)

user.Name = "Alice Smith"
db.Update(ctx, user)

db.Delete(ctx, "1", &User{})
```

Query with filters, ordering, and pagination:

```go
var results []*User

// Find users by field
db.List(ctx, &results, model.Where("email", "alice@example.com"))

// Complex queries
db.List(ctx, &results,
        model.WhereOp("age", ">=", 18),
        model.OrderDesc("name"),
        model.Limit(10),
        model.Offset(20),
)

count, _ := users.Count(ctx, model.Where("age", 30))
```

Swap backends with an option:

```go
// Development: in-memory (default)
service := micro.New("users")

// Production: SQLite or Postgres
db, _ := sqlite.New(model.WithDSN("file:app.db"))
service := micro.New("users", micro.Model(db))
```

Every service gets `Client()`, `Server()`, and `Model()` — call services, handle requests, and save data all from the same interface.

## Examples

Check out [/examples](examples/) for runnable code:
- [hello-world](examples/hello-world/) - Basic RPC service
- [web-service](examples/web-service/) - HTTP REST API
- [multi-service](examples/multi-service/) - Multiple services in one binary
- [mcp](examples/mcp/) - MCP integration with AI agents

See [all examples](examples/README.md) for more.

## Protobuf

Install the code generator and see usage in the docs:

```bash
go install go-micro.dev/v5/cmd/protoc-gen-micro@v5.16.0
```

> **Note:** Use a specific version instead of `@latest` to avoid module path conflicts. See [releases](https://github.com/micro/go-micro/releases) for the latest version.

Docs: [`internal/website/docs/getting-started.md`](internal/website/docs/getting-started.md)

## Command Line

Install the CLI:

```
go install go-micro.dev/v5/cmd/micro@v5.16.0
```

> **Note:** Use a specific version instead of `@latest` to avoid module path conflicts. See [releases](https://github.com/micro/go-micro/releases) for the latest version.

### Quick Start

```bash
micro new helloworld   # Create a new service
cd helloworld
micro run              # Run with API gateway and hot reload
```

Then open http://localhost:8080 to see your service and call it from the browser.

### Development Workflow

| Stage | Command | Purpose |
|-------|---------|---------|
| **Develop** | `micro run` | Local dev with hot reload and API gateway |
| **Build** | `micro build` | Compile production binaries |
| **Deploy** | `micro deploy` | Push to a remote Linux server via SSH + systemd |
| **Dashboard** | `micro server` | Optional production web UI with JWT auth |

### micro run

`micro run` starts your services with:
- **Web Dashboard** - Browse and call services at `/`
- **Agent Playground** - AI chat with MCP tools at `/agent`
- **API Explorer** - Browse endpoints and schemas at `/api`
- **API Gateway** - HTTP to RPC proxy at `/api/{service}/{method}` (no auth in dev mode)
- **MCP Tools** - Services as AI tools at `/api/mcp/tools`
- **Health Checks** - Aggregated health at `/health`
- **Hot Reload** - Auto-rebuild on file changes

> **Note:** `micro run` and `micro server` use a unified gateway architecture. See [Gateway Architecture](cmd/micro/README.md#gateway-architecture) for details.

```bash
micro run                    # Gateway on :8080
micro run --address :3000    # Custom gateway port
micro run --no-gateway       # Services only
micro run --env production   # Use production environment
```

### Configuration

For multi-service projects, create a `micro.mu` file:

```
service users
    path ./users
    port 8081

service posts
    path ./posts
    port 8082
    depends users

env development
    DATABASE_URL sqlite://./dev.db
```

The gateway runs on :8080 by default, so services should use other ports.

### Deployment

Deploy to any Linux server with systemd:

```bash
# On your server (one-time setup)
curl -fsSL https://go-micro.dev/install.sh | sh
sudo micro init --server

# From your laptop
micro deploy user@your-server
```

The deploy command:
1. Builds binaries for Linux
2. Copies via SSH to the server
3. Sets up systemd services
4. Verifies services are healthy

Optionally run `micro server` on the deployed machine for a production web dashboard with JWT auth, user management, and API explorer.

Manage deployed services:
```bash
micro status --remote user@server    # Check status
micro logs --remote user@server      # View logs
micro logs myservice --remote user@server -f  # Follow specific service
```

No Docker required. No Kubernetes. Just systemd.

See [internal/website/docs/deployment.md](internal/website/docs/deployment.md) for full deployment guide.

See [cmd/micro/README.md](cmd/micro/README.md) for full CLI documentation.

Docs: [`internal/website/docs`](internal/website/docs)

Package reference: https://pkg.go.dev/go-micro.dev/v5

**User Guides:**
- [Getting Started](internal/website/docs/getting-started.md)
- [Data Model](internal/website/docs/model.md)
- [MCP & AI Agents](internal/website/docs/mcp.md)
- [Plugins Overview](internal/website/docs/plugins.md)
- [Learn by Example](internal/website/docs/examples/index.md)
- [Deployment Guide](internal/website/docs/deployment.md)

**Architecture & Performance:**
- [Performance Considerations](internal/website/docs/performance.md)
- [Reflection Usage & Philosophy](internal/website/docs/REFLECTION-EVALUATION-SUMMARY.md)

**Security:**
- [TLS Security Migration](internal/website/docs/TLS_SECURITY_UPDATE.md)
- [Security Migration Guide](internal/website/docs/SECURITY_MIGRATION.md)

## Adopters

- [Sourse](https://sourse.eu) - Work in the field of earth observation, including embedded Kubernetes running onboard aircraft, and we’ve built a mission management SaaS platform using Go Micro.