go-mqtt

Enhanced Golang MQTT client wrapping github.com/eclipse/paho.mqtt.golang with automatic resubscription on reconnect.

CHINESE README

中文说明

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Main Features

🔄 Automatic Resubscription: Solves Paho client's missing auto-resubscribe feature on reconnect ⚡ OnConnect Callbacks: Subscription management via callback pattern 🔁 Repeat Logic: Built-in re-attempt mechanism handling connection operations with backoff ⏱️ Token Helpers: Simplified token status checking with timeout support 🛠️ Mate Ecosystem: Integrated with erero, must, rese to handle errors 📋 Structured Logging: Customizable logging interface with zap integration

Installation

go get github.com/go-xlan/go-mqtt

Requirements:

• Go 1.23.0 and above
• MQTT broker (e.g., EMQX, Mosquitto)

Quick Start

Basic Publish/Subscribe

This example demonstrates the core feature: creating publishing and subscribing clients with automatic resubscription on reconnect.

package main

import (
	"encoding/json"
	"math/rand/v2"
	"time"

	"github.com/go-xlan/go-mqtt/internal/utils"
	"github.com/go-xlan/go-mqtt/mqttgo"
	"github.com/yyle88/must"
	"github.com/yyle88/neatjson/neatjsons"
	"github.com/yyle88/rese"
	"github.com/yyle88/zaplog"
)

func main() {
	const mqttTopic = "mqtt-go-demo1-topic"

	config := &mqttgo.Config{
		BrokerServer: "ws://127.0.0.1:8083/mqtt",
		Username:     "username",
		Password:     "password",
		OrderMatters: false,
	}
	client1 := rese.V1(mqttgo.NewClientWithCallback(config, utils.NewUUID(), mqttgo.NewCallback().
		OnConnect(func(c mqttgo.Client, retryTimes uint64) (mqttgo.CallbackState, error) {
			return mqttgo.CallbackSuccess, nil
		}),
	))
	defer client1.Disconnect(500)

	client2 := rese.V1(mqttgo.NewClientWithCallback(config, utils.NewUUID(), mqttgo.NewCallback().
		OnConnect(func(c mqttgo.Client, retryTimes uint64) (mqttgo.CallbackState, error) {
			token := c.Subscribe(mqttTopic, 1, func(client mqttgo.Client, message mqttgo.Message) {
				zaplog.SUG.Debugln("subscribe-msg:", neatjsons.SxB(message.Payload()))
			})
			must.Same(rese.C1(mqttgo.CheckToken(token, time.Minute)), mqttgo.TokenStateSuccess)
			return mqttgo.CallbackSuccess, nil
		}),
	))
	defer client2.Disconnect(500)

	type MessageType struct {
		A string
		B int
		C float64
	}

	for i := 0; i < 10; i++ {
		msg := &MessageType{
			A: time.Now().String(),
			B: i,
			C: rand.Float64(),
		}
		contentBytes := rese.A1(json.Marshal(msg))

		zaplog.SUG.Debugln("publish-msg:", neatjsons.SxB(contentBytes))

		token := client1.Publish(mqttTopic, 1, false, contentBytes)
		must.Same(rese.C1(mqttgo.CheckToken(token, time.Second*3)), mqttgo.TokenStateSuccess)
		time.Sleep(time.Second)
	}
}

⬆️ Source: demo1x/main.go

With Repeat Logic

This example shows how to use callback states to manage re-attempt patterns on subscription issues.

package main

import (
	"encoding/json"
	"math/rand/v2"
	"time"

	"github.com/go-xlan/go-mqtt/internal/utils"
	"github.com/go-xlan/go-mqtt/mqttgo"
	"github.com/pkg/errors"
	"github.com/yyle88/erero"
	"github.com/yyle88/must"
	"github.com/yyle88/neatjson/neatjsons"
	"github.com/yyle88/rese"
	"github.com/yyle88/zaplog"
)

func main() {
	const mqttTopic = "mqtt-go-demo2-topic"

	config := &mqttgo.Config{
		BrokerServer: "ws://127.0.0.1:8083/mqtt",
		Username:     "username",
		Password:     "password",
		OrderMatters: false,
	}

	client1 := rese.V1(mqttgo.NewClientWithCallback(config, utils.NewUUID(), mqttgo.NewCallback().
		OnConnect(func(c mqttgo.Client, retryTimes uint64) (mqttgo.CallbackState, error) {
			if retryTimes > 10 {
				return mqttgo.CallbackTimeout, nil
			}
			if rand.IntN(100) >= 10 {
				return mqttgo.CallbackUnknown, erero.New("random-rate-not-success")
			}
			return mqttgo.CallbackSuccess, nil
		}),
	))
	defer client1.Disconnect(500)

	client2 := rese.V1(mqttgo.NewClientWithCallback(config, utils.NewUUID(), mqttgo.NewCallback().
		OnConnect(func(c mqttgo.Client, retryTimes uint64) (mqttgo.CallbackState, error) {
			token := c.Subscribe(mqttTopic, 1, func(client mqttgo.Client, message mqttgo.Message) {
				zaplog.SUG.Debugln("subscribe-msg:", neatjsons.SxB(message.Payload()))
			})
			tokenState, err := mqttgo.WaitToken(token)
			if err != nil {
				return mqttgo.CallbackRetries, errors.WithMessage(err, "subscribe-is-wrong")
			}
			must.Same(tokenState, mqttgo.TokenStateSuccess)
			return mqttgo.CallbackSuccess, nil
		}),
	))
	defer client2.Disconnect(500)

	type MessageType struct {
		A string
		B int
		C float64
	}

	for i := 0; i < 100; i++ {
		msg := &MessageType{
			A: time.Now().String(),
			B: i,
			C: rand.Float64(),
		}
		contentBytes := rese.A1(json.Marshal(msg))

		zaplog.SUG.Debugln("publish-msg:", neatjsons.SxB(contentBytes))

		token := client1.Publish(mqttTopic, 1, false, contentBytes)
		must.Same(rese.C1(mqttgo.CheckToken(token, time.Second*3)), mqttgo.TokenStateSuccess)
		time.Sleep(time.Second)
	}
}

⬆️ Source: demo2x/main.go

API Reference

Core Functions

NewClientWithCallback(config *Config, clientID string, callback *Callback) (mqtt.Client, error)

Creates MQTT client with automatic resubscription support via OnConnect callbacks.

Parameters:

• config: MQTT broker configuration
• clientID: Unique client ID
• callback: OnConnect callback handlers managing subscriptions

Returns: Connected MQTT client / error

NewClient(opts *mqtt.ClientOptions) (mqtt.Client, error)

Creates basic MQTT client with given options. Waits on connection success.

NewCallback() *Callback

Creates callback collection handling connection events.

(*Callback).OnConnect(handler func(client mqtt.Client, retryTimes uint64) (CallbackState, error)) *Callback

Registers callback to run on connect/reconnect. Supports chaining multiple handlers.

Token Utilities

CheckToken(token mqtt.Token, timeout time.Duration) (TokenState, error)

Checks token completion with timeout.

Returns:

• TokenStateSuccess: Operation completed
• TokenStateTimeout: Exceeded timeout
• TokenStateUnknown: Error occurred

WaitToken(token mqtt.Token) (TokenState, error)

Waits on token completion without timeout.

Configuration

type Config struct {
    BrokerServer string // MQTT broker URL (tcp:// or ws://)
    Username     string // Authentication username
    Password     string // Authentication password
    OrderMatters bool   // Whether message order matters
}

Callback States

const (
    CallbackSuccess CallbackState = "success" // Operation succeeded
    CallbackRetries CallbackState = "retries" // Retry requested
    CallbackTimeout CallbackState = "timeout" // Stop retrying
    CallbackUnknown CallbackState = "unknown" // Unknown error, retry
)

Examples

TCP Connection

config := &mqttgo.Config{
    BrokerServer: "tcp://localhost:1883",
    Username:     "username",
    Password:     "password",
}

WebSocket Connection

config := &mqttgo.Config{
    BrokerServer: "ws://127.0.0.1:8083/mqtt",
    Username:     "username",
    Password:     "password",
}

Multiple Subscription Topics

callback := mqttgo.NewCallback().
    OnConnect(func(c mqttgo.Client, retryTimes uint64) (mqttgo.CallbackState, error) {
        topics := map[string]byte{
            "topic/one":   1,
            "topic/two":   1,
            "topic/three": 2,
        }
        token := c.SubscribeMultiple(topics, messageHandler)
        state, err := mqttgo.WaitToken(token)
        if err != nil || state != mqttgo.TokenStateSuccess {
            return mqttgo.CallbackRetries, err
        }
        return mqttgo.CallbackSuccess, nil
    })

Custom Retry Logic

Timeout past 10 retries:

OnConnect(func(c mqttgo.Client, retryTimes uint64) (mqttgo.CallbackState, error) {
    if retryTimes > 10 {
        return mqttgo.CallbackTimeout, nil
    }
    token := c.Subscribe("topic", 1, handler)
    state, err := mqttgo.CheckToken(token, time.Second*5)
    if err != nil {
        return mqttgo.CallbackRetries, err
    }
    return mqttgo.CallbackSuccess, nil
})

Immediate retry on failures:

OnConnect(func(c mqttgo.Client, retryTimes uint64) (mqttgo.CallbackState, error) {
    token := c.Subscribe("topic", 1, handler)
    if state, err := mqttgo.WaitToken(token); err != nil {
        return mqttgo.CallbackRetries, err
    }
    return mqttgo.CallbackSuccess, nil
})

Custom Logger

type CustomLogger struct{}

func (l *CustomLogger) ErrorLog(msg string, fields ...zap.Field) {
    // Your error logging logic
}

func (l *CustomLogger) DebugLog(msg string, fields ...zap.Field) {
    // Your debug logging logic
}

func main() {
    mqttgo.SetLog(&CustomLogger{})
    // Create clients...
}

What makes go-mqtt different?

The Eclipse Paho MQTT client does not auto-resubscribe to topics following reconnection (Issue #22). This package solves that problem:

1. OnConnect Callbacks: Executes subscription logic on each connect/reconnect
2. Retry Mechanism: Auto retries failed subscriptions with 100ms backoff
3. State Management: Simple callback states to manage retry patterns
4. Mate Integration: Leverages rese, must, erero to write clean code

Running EMQX to Test

See internal/sketches/sketch1/README.md about Docker setup instructions.

Running Embedded MQTT

See internal/sketches/sketch2/README.md about embedded MQTT setup using github.com/mochi-mqtt/server/v2.

📄 License

MIT License. See LICENSE.

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🤝 Contributing

Contributions are welcome! Report bugs, suggest features, and contribute code:

• 🐛 Found a mistake? Open an issue on GitHub with reproduction steps
• 💡 Have a feature idea? Create an issue to discuss the suggestion
• 📖 Documentation confusing? Report it so we can improve
• 🚀 Need new features? Share the use cases to help us understand requirements
• ⚡ Performance issue? Help us optimize through reporting slow operations
• 🔧 Configuration problem? Ask questions about complex setups
• 📢 Follow project progress? Watch the repo to get new releases and features
• 🌟 Success stories? Share how this package improved the workflow
• 💬 Feedback? We welcome suggestions and comments

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🔧 Development

New code contributions, follow this process:

1. Fork: Fork the repo on GitHub (using the webpage UI).
2. Clone: Clone the forked project (git clone https://github.com/yourname/repo-name.git).
3. Navigate: Navigate to the cloned project (cd repo-name)
4. Branch: Create a feature branch (git checkout -b feature/xxx).
5. Code: Implement the changes with comprehensive tests
6. Testing: (Golang project) Ensure tests pass (go test ./...) and follow Go code style conventions
7. Documentation: Update documentation to support client-facing changes and use significant commit messages
8. Stage: Stage changes (git add .)
9. Commit: Commit changes (git commit -m "Add feature xxx") ensuring backward compatible code
10. Push: Push to the branch (git push origin feature/xxx).
11. PR: Open a merge request on GitHub (on the GitHub webpage) with detailed description.

Please ensure tests pass and include relevant documentation updates.

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🌟 Support

Welcome to contribute to this project via submitting merge requests and reporting issues.

Project Support:

• ⭐ Give GitHub stars if this project helps you
• 🤝 Share with teammates and (golang) programming friends
• 📝 Write tech blogs about development tools and workflows - we provide content writing support
• 🌟 Join the ecosystem - committed to supporting open source and the (golang) development scene

Have Fun Coding with this package! 🎉🎉🎉

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