Go - Noorle

Build WebAssembly plugins using Go. Noorle uses TinyGo to compile Go to WASI Preview 2 WebAssembly.

Setup

Install TinyGo

# Install TinyGo (required for Go plugins)
wget https://github.com/tinygo-org/tinygo/releases/download/v0.30.0/tinygo_0.30.0_amd64.deb
sudo dpkg -i tinygo_0.30.0_amd64.deb

# Or on macOS
brew install tinygo

# Create a new Go plugin
noorle plugin new my-go-plugin --lang go
cd my-go-plugin

Project Structure

my-go-plugin/
├── main.go               # Entry point and tools
├── tools/
│   └── process.go        # Tool implementations
├── go.mod                # Module definition
├── go.sum                # Dependencies
├── noorle.yaml           # Plugin config
├── world.wit             # Component interface
├── .env
└── Makefile

Define Tools

Export functions as plugin tools.

Simple Functions

// main.go
package main

// Greet returns a greeting
func Greet(name string) string {
    return "Hello, " + name + "!"
}

// Add returns the sum of two numbers
func Add(a, b float64) float64 {
    return a + b
}

// Multiply returns the product
func Multiply(a, b float64) float64 {
    return a * b
}

Complex Types

package main

type Item struct {
    ID    string `json:"id"`
    Name  string `json:"name"`
    Count int    `json:"count"`
}

type Config map[string]string

type Result struct {
    Success bool   `json:"success"`
    Data    string `json:"data"`
    Error   string `json:"error,omitempty"`
}

// ProcessItems transforms items with config
func ProcessItems(items []Item, config Config) []Item {
    result := make([]Item, len(items))
    prefix, ok := config["prefix"]
    if !ok {
        prefix = ""
    }

    for i, item := range items {
        result[i] = Item{
            ID:    item.ID,
            Name:  prefix + item.Name,
            Count: item.Count,
        }
    }
    return result
}

// SearchItems returns matching items
func SearchItems(query string, limit int) []Item {
    if limit <= 0 {
        limit = 10
    }
    if limit > 100 {
        limit = 100
    }

    result := make([]Item, limit)
    for i := 0; i < limit; i++ {
        result[i] = Item{
            ID:    string(rune(i)),
            Name:  query + "_" + string(rune(i)),
            Count: i + 1,
        }
    }
    return result
}

File I/O

Access filesystem via standard library.

package main

import (
    "os"
    "path/filepath"
)

func ReadConfig() (string, error) {
    data, err := os.ReadFile("/allowed/path/config.json")
    if err != nil {
        return "", err
    }
    return string(data), nil
}

func WriteCache(key, value string) (bool, error) {
    cacheDir := os.Getenv("CACHE_DIR")
    if cacheDir == "" {
        cacheDir = "/cache"
    }

    filePath := filepath.Join(cacheDir, key+".txt")
    err := os.WriteFile(filePath, []byte(value), 0644)
    return err == nil, err
}

func ListFiles(directory string) ([]string, error) {
    entries, err := os.ReadDir(directory)
    if err != nil {
        return nil, err
    }

    var files []string
    for _, entry := range entries {
        if !entry.IsDir() {
            files = append(files, entry.Name())
        }
    }
    return files, nil
}

Configure Permissions

In noorle.yaml:

permissions:
  filesystem:
    allow:
      - uri: "fs://cache/**"
        access: [read, write]
      - uri: "fs://config/**"
        access: [read]

  environment:
    allow:
      - key: "CACHE_DIR"

Environment Variables

Access configuration via os.Getenv().

package main

func GetApiCredentials() map[string]string {
    return map[string]string{
        "api_key":    os.Getenv("API_KEY"),
        "api_secret": os.Getenv("API_SECRET"),
    }
}

func GetDatabaseUrl() string {
    url := os.Getenv("DATABASE_URL")
    if url == "" {
        return "sqlite:///:memory:"
    }
    return url
}

func GetConfig() map[string]string {
    return map[string]string{
        "debug":      os.Getenv("DEBUG"),
        "log_level":  os.Getenv("LOG_LEVEL"),
        "timeout":    os.Getenv("TIMEOUT"),
    }
}

Configure in .env:

API_KEY=sk-1234567890
API_SECRET=secret-value
DATABASE_URL=postgres://localhost/mydb
DEBUG=true
LOG_LEVEL=debug

Network Access

Make HTTP requests via standard library.

package main

import (
    "io"
    "net/http"
)

func FetchData(url string) (string, error) {
    resp, err := http.Get(url)
    if err != nil {
        return "", err
    }
    defer resp.Body.Close()

    data, err := io.ReadAll(resp.Body)
    return string(data), err
}

func PostJSON(url string, jsonData string) (string, error) {
    resp, err := http.Post(
        url,
        "application/json",
        strings.NewReader(jsonData),
    )
    if err != nil {
        return "", err
    }
    defer resp.Body.Close()

    data, err := io.ReadAll(resp.Body)
    return string(data), err
}

func CallApi(endpoint string, params map[string]string) (string, error) {
    url := "https://api.example.com/" + endpoint + "?"
    first := true
    for k, v := range params {
        if !first {
            url += "&"
        }
        url += k + "=" + url.QueryEscape(v)
        first = false
    }

    resp, err := http.Get(url)
    if err != nil {
        return "", err
    }
    defer resp.Body.Close()

    data, err := io.ReadAll(resp.Body)
    return string(data), err
}

Configure network permissions:

permissions:
  network:
    allow:
      - host: "api.example.com"
      - host: "*.github.com"

Error Handling

Return errors as structured responses.

package main

type Response struct {
    Success bool        `json:"success"`
    Data    interface{} `json:"data,omitempty"`
    Error   string      `json:"error,omitempty"`
}

func SafeOperation(input string) Response {
    if input == "" {
        return Response{
            Success: false,
            Error:   "Empty input",
        }
    }

    result, err := process(input)
    if err != nil {
        return Response{
            Success: false,
            Error:   err.Error(),
        }
    }

    return Response{
        Success: true,
        Data:    result,
    }
}

func process(input string) (string, error) {
    if input == "" {
        return "", errors.New("invalid input")
    }
    return strings.ToUpper(input), nil
}

Dependencies

go.mod

module my-go-plugin

go 1.21

require (
    github.com/google/uuid v1.5.0
)

Add Dependencies

go get github.com/google/uuid
noorle plugin build

Size Optimization

Go WASM is typically 1-3MB. Minimize with:

# Build with optimizations
GOOS=js GOARCH=wasm go build -ldflags="-s -w"

Testing

Test locally before uploading.

// main_test.go
package main

import (
    "testing"
)

func TestGreet(t *testing.T) {
    result := Greet("Alice")
    expected := "Hello, Alice!"
    if result != expected {
        t.Errorf("Expected %q, got %q", expected, result)
    }
}

func TestAdd(t *testing.T) {
    if Add(2, 3) != 5 {
        t.Fail()
    }
}

Run tests:

go test ./...

Building and Deploying

Build

noorle plugin build

# Output:
# ✓ Building plugin...
# ✓ Compiling Go to WebAssembly
# ✓ Creating my-go-plugin.npack (1.2MB)

Upload

noorle plugin push --api-key YOUR_KEY

# Output:
# ✓ Uploading plugin...
# ✓ Plugin ID: 550e8400-e29b-41d4-a716-446655440000
# ✓ Active version: v1
# ✓ Tools: Greet, Add, ProcessItems

Best Practices

Input Validation

func ValidateEmail(email string) map[string]interface{} {
    errors := []string{}

    if email == "" {
        errors = append(errors, "Email cannot be empty")
    }

    if !strings.Contains(email, "@") {
        errors = append(errors, "Email must contain @")
    }

    if len(email) > 255 {
        errors = append(errors, "Email too long")
    }

    if len(errors) > 0 {
        return map[string]interface{}{
            "valid":  false,
            "errors": errors,
        }
    }

    return map[string]interface{}{
        "valid": true,
    }
}

Logging

import "log"

func LogInfo(msg string) {
    log.Printf("[INFO] %s\n", msg)
}

func MyTool(input string) string {
    LogInfo("Processing: " + input)
    result := process(input)
    LogInfo("Completed")
    return result
}

Documentation

// ProcessWeatherData processes raw weather data
// and returns formatted results.
//
// city: The city name
// units: Temperature units (celsius or fahrenheit)
//
// Returns: Weather summary or error
func GetWeather(city, units string) (string, error) {
    // Implementation
}

Example: Complete Plugin

// main.go
package main

import (
    "encoding/json"
    "io"
    "net/http"
    "os"
)

type Weather struct {
    City        string `json:"city"`
    Temp        float64 `json:"temp"`
    Description string `json:"description"`
}

func GetWeather(city, units string) (Weather, error) {
    apiKey := os.Getenv("OPENWEATHER_API_KEY")
    if apiKey == "" {
        return Weather{}, errors.New("API key not configured")
    }

    url := "https://api.openweathermap.org/data/2.5/weather?q=" +
        city + "&appid=" + apiKey + "&units=" + units

    resp, err := http.Get(url)
    if err != nil {
        return Weather{}, err
    }
    defer resp.Body.Close()

    var data map[string]interface{}
    body, _ := io.ReadAll(resp.Body)
    json.Unmarshal(body, &data)

    main := data["main"].(map[string]interface{})
    weather := data["weather"].([]interface{})[0].(map[string]interface{})

    return Weather{
        City:        data["name"].(string),
        Temp:        main["temp"].(float64),
        Description: weather["description"].(string),
    }, nil
}

Troubleshooting

Build fails - “TinyGo not found”:

# Install TinyGo
brew install tinygo
# or from source
git clone https://github.com/tinygo-org/tinygo
cd tinygo && make

Plugin too large (>5MB):

Remove unnecessary dependencies
Use go mod tidy to clean up
Enable -s -w in LDFLAGS

Runtime issues with dependencies:

Ensure go.mod is correct
Use go get to fetch versions
Rebuild after dependency changes

Getting Started

Plugin Development

Language Guides

Deployment

Go

Setup

Install TinyGo

Project Structure

Define Tools

Simple Functions

Complex Types

File I/O

Configure Permissions

Environment Variables

Network Access

Error Handling

Dependencies

go.mod

Add Dependencies

Size Optimization

Testing

Building and Deploying

Build

Upload

Best Practices

Input Validation

Logging

Documentation

Example: Complete Plugin

Troubleshooting

Next Steps

​Setup

​Install TinyGo

​Project Structure

​Define Tools

​Simple Functions

​Complex Types

​File I/O

​Configure Permissions

​Environment Variables

​Network Access

​Error Handling

​Dependencies

​go.mod

​Add Dependencies

​Size Optimization

​Testing

​Building and Deploying

​Build

​Upload

​Best Practices

​Input Validation

​Logging

​Documentation

​Example: Complete Plugin

​Troubleshooting

​Next Steps

Setup

Install TinyGo

Project Structure

Define Tools

Simple Functions

Complex Types

File I/O

Configure Permissions

Environment Variables

Network Access

Error Handling

Dependencies

go.mod

Add Dependencies

Size Optimization

Testing

Building and Deploying

Build

Upload

Best Practices

Input Validation

Logging

Documentation

Example: Complete Plugin

Troubleshooting

Next Steps