---
id: services
title: 🥡 Services
sidebar_position: 9
---

Services provide external services needed to run the application, stored as dependencies in the application's State Management. They are supposed to be used while developing and testing the application, being started and stopped automatically by the application.

Once you add a service to the configuration of the GoFiber application, it is automatically started when the application starts and stopped when the application shuts down. You can retrieve the service from the application's State using the `GetService` or `MustGetService` functions (see [State Management](../api/state)).

## Service Interface

`Service` is an interface that defines the methods for a service.

### Definition

```go
// Service is an interface that defines the methods for a service.
type Service interface {
    // Start starts the service, returning an error if it fails.
    Start(ctx context.Context) error

    // String returns a string representation of the service.
    // It is used to print a human-readable name of the service in the startup message.
    String() string

    // State returns the current state of the service.
    State(ctx context.Context) (string, error)

    // Terminate terminates the service, returning an error if it fails.
    Terminate(ctx context.Context) error
}
```

## Methods on the Service

### Start

Starts the service, returning an error if it fails. This method is automatically called when the application starts.

```go
func (s *SomeService) Start(ctx context.Context) error
```

### String

Returns a string representation of the service, used to print the service in the startup message.

```go
func (s *SomeService) String() string
```

### State

Returns the current state of the service, used to print the service in the startup message.

```go
func (s *SomeService) State(ctx context.Context) (string, error)
```

### Terminate

Terminate terminates the service after the application shuts down using a post shutdown hook, returning an error if it fails.

```go
func (s *SomeService) Terminate(ctx context.Context) error
```

## Comprehensive Examples

### Example: Adding a service

This example demonstrates how to add a Redis store as a service to the application, backed by the Testcontainers Redis Go module.

```go
package main

import (
    "context"
    "fmt"
    "log"
    "time"

    "github.com/gofiber/fiber/v3"
    "github.com/redis/go-redis/v9"
    tcredis "github.com/testcontainers/testcontainers-go/modules/redis"
)

const redisServiceName = "redis-store"

type redisService struct {
    ctr *tcredis.RedisContainer
}

// Start initializes and starts the service. It implements the [fiber.Service] interface.
func (s *redisService) Start(ctx context.Context) error {
    // start the service
    c, err := tcredis.Run(ctx, "redis:latest")
    if err != nil {
        return err
    }

    s.ctr = c
    return nil
}

// String returns a string representation of the service.
// It is used to print a human-readable name of the service in the startup message.
// It implements the [fiber.Service] interface.
func (s *redisService) String() string {
    return redisServiceName
}

// State returns the current state of the service.
// It implements the [fiber.Service] interface.
func (s *redisService) State(ctx context.Context) (string, error) {
    state, err := s.ctr.State(ctx)
    if err != nil {
        return "", fmt.Errorf("container state: %w", err)
    }

    return state.Status, nil
}

// Terminate stops and removes the service. It implements the [fiber.Service] interface.
func (s *redisService) Terminate(ctx context.Context) error {
    // stop the service
    return s.ctr.Terminate(ctx)
}

func main() {
    cfg := &fiber.Config{}

    // Initialize service.
    cfg.Services = append(cfg.Services, &redisService{})

    // Define a context provider for the services startup.
    // This is useful to cancel the startup of the services if the context is canceled.
    // Default is context.Background().
    startupCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
    defer cancel()
    cfg.ServicesStartupContextProvider = func() context.Context {
        return startupCtx
    }

    // Define a context provider for the services shutdown.
    // This is useful to cancel the shutdown of the services if the context is canceled.
    // Default is context.Background().
    shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
    defer cancel()
    cfg.ServicesShutdownContextProvider = func() context.Context {
        return shutdownCtx
    }

    app := fiber.New(*cfg)

    ctx := context.Background()

    // Obtain the Redis service from the application's State.
    redisSrv, ok := fiber.GetService[*redisService](app.State(), redisServiceName)
    if !ok || redisSrv == nil {
        log.Printf("Redis service not found")
        return
    }

    // Obtain the connection string from the service.
    connString, err := redisSrv.ctr.ConnectionString(ctx)
    if err != nil {
        log.Printf("Could not get connection string: %v", err)
        return
    }

    // Parse the connection string to create a Redis client.
    options, err := redis.ParseURL(connString)
    if err != nil {
        log.Printf("failed to parse connection string: %s", err)
        return
    }

    // Initialize the Redis client.
    rdb := redis.NewClient(options)

    // Check the Redis connection.
    if err := rdb.Ping(ctx).Err(); err != nil {
        log.Fatalf("Could not connect to Redis: %v", err)
    }

    app.Listen(":3000")
}

```

### Example: Adding a service with a Store Middleware

This example demonstrates how to use Services with the Store Middleware for dependency injection in a Fiber application. It uses a Redis store, backed by the Testcontainers Redis Go module.

```go
package main

import (
    "context"
    "encoding/json"
    "fmt"
    "log"
    "time"

    "github.com/gofiber/fiber/v3"
    "github.com/gofiber/fiber/v3/middleware/logger"
    redisStore "github.com/gofiber/storage/redis/v3"
    "github.com/redis/go-redis/v9"
    tcredis "github.com/testcontainers/testcontainers-go/modules/redis"
)

const (
    redisServiceName = "redis-store"
)

type User struct {
    ID    int    `json:"id"`
    Name  string `json:"name"`
    Email string `json:"email"`
}

type redisService struct {
    ctr *tcredis.RedisContainer
}

// Start initializes and starts the service. It implements the [fiber.Service] interface.
func (s *redisService) Start(ctx context.Context) error {
    // start the service
    c, err := tcredis.Run(ctx, "redis:latest")
    if err != nil {
        return err
    }

    s.ctr = c
    return nil
}

// String returns a string representation of the service.
// It is used to print a human-readable name of the service in the startup message.
// It implements the [fiber.Service] interface.
func (s *redisService) String() string {
    return redisServiceName
}

// State returns the current state of the service.
// It implements the [fiber.Service] interface.
func (s *redisService) State(ctx context.Context) (string, error) {
    state, err := s.ctr.State(ctx)
    if err != nil {
        return "", fmt.Errorf("container state: %w", err)
    }

    return state.Status, nil
}

// Terminate stops and removes the service. It implements the [fiber.Service] interface.
func (s *redisService) Terminate(ctx context.Context) error {
    // stop the service
    return s.ctr.Terminate(ctx)
}

func main() {
    cfg := &fiber.Config{}

    // Initialize service.
    cfg.Services = append(cfg.Services, &redisService{})

    // Define a context provider for the services startup.
    // This is useful to cancel the startup of the services if the context is canceled.
    // Default is context.Background().
    startupCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
    defer cancel()
    cfg.ServicesStartupContextProvider = func() context.Context {
        return startupCtx
    }

    // Define a context provider for the services shutdown.
    // This is useful to cancel the shutdown of the services if the context is canceled.
    // Default is context.Background().
    shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
    defer cancel()
    cfg.ServicesShutdownContextProvider = func() context.Context {
        return shutdownCtx
    }

    app := fiber.New(*cfg)

    // Initialize default config
    app.Use(logger.New())

    ctx := context.Background()

    // Obtain the Redis service from the application's State.
    redisSrv, ok := fiber.GetService[*redisService](app.State(), redisServiceName)
    if !ok || redisSrv == nil {
        log.Printf("Redis service not found")
        return
    }

    // Obtain the connection string from the service.
    connString, err := redisSrv.ctr.ConnectionString(ctx)
    if err != nil {
        log.Printf("Could not get connection string: %v", err)
        return
    }

    // define a GoFiber session store, backed by the Redis service
    store := redisStore.New(redisStore.Config{
        URL: connString,
    })

    app.Post("/user/create", func(c fiber.Ctx) error {
        var user User
        if err := c.Bind().JSON(&user); err != nil {
            return c.Status(fiber.StatusBadRequest).SendString(err.Error())
        }

        json, err := json.Marshal(user)
        if err != nil {
            return c.Status(fiber.StatusInternalServerError).SendString(err.Error())
        }

        // Save the user to the database.
        err = store.Set(user.Email, json, time.Hour*24)
        if err != nil {
            return c.Status(fiber.StatusInternalServerError).SendString(err.Error())
        }

        return c.JSON(user)
    })

    app.Get("/user/:id", func(c fiber.Ctx) error {
        id := c.Params("id")

        user, err := store.Get(id)
        if err == redis.Nil {
            return c.Status(fiber.StatusNotFound).SendString("User not found")
        } else if err != nil {
            return c.Status(fiber.StatusInternalServerError).SendString(err.Error())
        }

        return c.JSON(string(user))
    })

    app.Listen(":3000")
}

```