go-fcm

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Forked from github.com/edganiukov/fcm
Firebase Cloud Messaging Official Documentation

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Table of Contents

• go-fcm
  • Table of Contents
  • Features
  • Supported Message Types
  • Quick Start
  • Authentication and Credentials
  • Usage Example
  • Advanced Configuration
    • Custom HTTP Client
    • Proxy Support
    • Unit Testing and Mock
  • Best Practices
  • Troubleshooting
  • Architecture Diagram
  • FAQ
  • License

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Features

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Supported Message Types

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Quick Start

Install go-fcm:

go get github.com/appleboy/go-fcm

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Authentication and Credentials

It is recommended to use Google Application Default Credentials (ADC) for authentication.
Download the JSON key from Firebase Console > Settings > Service Accounts and set the environment variable:

export GOOGLE_APPLICATION_CREDENTIALS="/path/to/serviceAccountKey.json"

Alternatively, specify the key path directly in your code.

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Usage Example

package main

import (
  "context"
  "fmt"
  "log"

  "firebase.google.com/go/v4/messaging"
  fcm "github.com/appleboy/go-fcm"
)

func main() {
  ctx := context.Background()
  client, err := fcm.NewClient(
    ctx,
    fcm.WithCredentialsFile("path/to/serviceAccountKey.json"),
    // fcm.WithServiceAccount("my-client-id@my-project-id.iam.gserviceaccount.com"),
  )
  if err != nil {
    log.Fatal(err)
  }

  // Send to a single device
  token := "YOUR_DEVICE_TOKEN"
  resp, err := client.Send(
    ctx,
    &messaging.Message{
      Token: token,
      Data: map[string]string{
        "foo": "bar",
      },
    },
  )
  if err != nil {
    log.Fatal(err)
  }
  fmt.Println("Success:", resp.SuccessCount, "Failure:", resp.FailureCount)

  // Send to a topic
  resp, err = client.Send(
    ctx,
    &messaging.Message{
      Data: map[string]string{
        "foo": "bar",
      },
      Topic: "highScores",
    },
  )
  if err != nil {
    log.Fatal(err)
  }

  // Send with condition
  condition := "'stock-GOOG' in topics || 'industry-tech' in topics"
  message := &messaging.Message{
    Data: map[string]string{
      "score": "850",
      "time":  "2:45",
    },
    Condition: condition,
  }
  resp, err = client.Send(ctx, message)
  if err != nil {
    log.Fatal(err)
  }

  // Send to multiple devices
  registrationToken := "YOUR_REGISTRATION_TOKEN"
  messages := []*messaging.Message{
    {
      Notification: &messaging.Notification{
        Title: "Price drop",
        Body:  "5% off all electronics",
      },
      Token: registrationToken,
    },
    {
      Notification: &messaging.Notification{
        Title: "Price drop",
        Body:  "2% off all books",
      },
      Topic: "readers-club",
    },
  }
  resp, err = client.Send(ctx, messages...)
  if err != nil {
    log.Fatal(err)
  }

  // Multicast messaging
  registrationTokens := []string{
    "YOUR_REGISTRATION_TOKEN_1",
    "YOUR_REGISTRATION_TOKEN_2",
    // ...
  }
  msg := &messaging.MulticastMessage{
    Data: map[string]string{
      "score": "850",
      "time":  "2:45",
    },
    Tokens: registrationTokens,
  }
  resp, err = client.SendMulticast(ctx, msg)
  if err != nil {
    log.Fatal(err)
  }
  fmt.Printf("%d messages were sent successfully\n", resp.SuccessCount)
  if resp.FailureCount > 0 {
    var failedTokens []string
    for idx, resp := range resp.Responses {
      if !resp.Success {
        failedTokens = append(failedTokens, registrationTokens[idx])
      }
    }
    fmt.Printf("List of tokens that caused failures: %v\n", failedTokens)
  }
}

---

Advanced Configuration

Custom HTTP Client

import (
  "crypto/tls"
  "net"
  "net/http"
  "time"
  "golang.org/x/net/http2"
)

func main() {
  httpTimeout := 5 * time.Second
  tlsTimeout := 5 * time.Second

  transport := &http2.Transport{
    DialTLS: func(network, addr string, cfg *tls.Config) (net.Conn, error) {
      return tls.DialWithDialer(&net.Dialer{Timeout: tlsTimeout}, network, addr, cfg)
    },
  }

  httpClient := &http.Client{
    Transport: transport,
    Timeout:   httpTimeout,
  }

  ctx := context.Background()
  client, err := fcm.NewClient(
    ctx,
    fcm.WithCredentialsFile("path/to/serviceAccountKey.json"),
    fcm.WithHTTPClient(httpClient),
  )
}

Proxy Support

func main() {
  ctx := context.Background()
  client, err := fcm.NewClient(
    ctx,
    fcm.WithCredentialsFile("path/to/serviceAccountKey.json"),
    fcm.WithHTTPProxy("http://localhost:8088"),
  )
}

Unit Testing and Mock

import (
  "context"
  "net/http"
  "net/http/httptest"
  "testing"

  "firebase.google.com/go/v4/messaging"
  fcm "github.com/appleboy/go-fcm"
  "google.golang.org/api/option"
)

func TestMockClient(t *testing.T) {
  server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    w.WriteHeader(http.StatusOK)
    w.Header().Set("Content-Type", "application/json")
    _, _ = w.Write([]byte(`{"name": "q1w2e3r4"}`))
  }))
  defer server.Close()

  client, err := fcm.NewClient(
    context.Background(),
    fcm.WithEndpoint(server.URL),
    fcm.WithProjectID("test"),
    fcm.WithCustomClientOption(option.WithoutAuthentication()),
  )
  if err != nil {
    t.Fatalf("unexpected error: %v", err)
  }
  resp, err := client.Send(
    context.Background(),
    &messaging.Message{
      Token: "test",
      Data: map[string]string{
        "foo": "bar",
      },
    })
  if err != nil {
    t.Fatalf("unexpected error: %v", err)
  }
  // Check response
  if resp.SuccessCount != 1 {
    t.Fatalf("expected 1 successes, got: %d", resp.SuccessCount)
  }
  if resp.FailureCount != 0 {
    t.Fatalf("expected 0 failures, got: %d", resp.FailureCount)
  }
}

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Best Practices

[!TIP]

• For batch messaging, limit each batch to no more than 500 tokens.
• Prefer using Topics to manage device groups instead of direct token management.
• Set your credentials file as read-only and store it securely.

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Troubleshooting

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Architecture Diagram

flowchart TD
    A[Your Go Server] -->|go-fcm| B[FCM API]
    B --> C[Android/iOS/Web Device]
    B -.-> D[Topic/Condition Routing]

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FAQ

• Q: How do I obtain an FCM device token?
• Q: How do I set up multi-language notifications?
• Q: How do I track message delivery status?

For more, see the Firebase Official FAQ

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License

This project is licensed under the MIT License.

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