How To Add Firebase Authentication To Your Golang Application

How To Add Firebase Authentication To Your Golang Application

In this tutorial, we will walk you through the step-by-step process of securing Golang apps by integrating Firebase authentication providers.


firebase-authentication-golang

Firebase Authentication, part of the Firebase platform by Google, provides a straightforward and secure means of managing user authentication.

Firebase Authentication supports various authentication methods including email/password, social providers such as Google and Facebook, and more.

Firebase also offers an Admin SDK designed for Golang apps, streamlining authentication integration. The Admin SDK handles security complexities like password hashing, allowing you to concentrate on developing your application's core features.

In this article, you will learn how to connect firebase authentication with your Golang app.

Prerequisites

Before you get into the article, you should have the following:

  1. A basic understanding of Golang and how to set up a basic web server in Go. If you do not have Golang installed on your machine, go to the official Go website and download the version for your operating system.

    Use the following command to check whether Go was installed correctly:

    go version
    

    If Go was installed correctly, you should get the version of Go installed on your machine, which looks like this: go version go1.22.4 windows/amd64.

  2. A Firebase project and knowledge of the Firebase Console. Don't worry too much about this as I will walk you through how to navigate the Firebase Console and set up a Firebase project.

  3. A code editor of your choice.

Now that you've covered the prerequisites, you're all set to begin the project. Let's begin by setting up your Firebase project.

Setting Up Firebase Authentication

Creating a Firebase Project

Follow these steps to set up your Firebase project:

  1. Go to the Firebase Developer Console, sign in with your Gmail address, and click on the Go to Console button at the top right corner to navigate to the console's overview page.

  2. On the overview page, click on Create new project to create a new project and provide a name for your project.

  3. After creating your project, you will be redirected to the overview page of your product. You need to add Firebase to your app to generate your API keys and configuration file.

    To add Firebase to your app, click the web icon (highlighted in the image below), provide the app name, and click on the Register app button.

    1

  4. After registering your Golang app, Firebase will provide your app's configuration code. This configuration code contains your API keys as well as details specific to your app.

    2

    Note: Check the "Use a script tag" since we are going to use plain HTML

    Copy the configuration code as you will need it later when connecting Firebase to your Golang app.

Well done! You have successfully created a new Firebase project and registered a web application within that project.

In the next section, you will learn how to configure Firebase authentication in the Firebase Console.

Configuring Firebase Authentication

After registering your app, the next step is to configure the Firebase Authentication service.

To configure the Firebase Authentication service:

  1. Select the Authentication section in your project's overview page.

3

  1. Click on the Get started button

4

Firebase supports various authentication methods, but for simplicity, we'll focus on email/password authentication. Implementing other methods follows a similar process.

On the Authentication settings page, select the Sign-in method tab and click on the Email/password provider.

5

Toggle the Enable button and click on Save. For this tutorial, we will leave out the Email link feature.

6

After saving the changes, the Email/password authentication method should be Enabled.

You can click on Add provider button to add more authentication methods.

Well done! You have configured the Firebase Authentication service by adding the Email/password provider.

You are now set to dive into creating your Golang application and integrating the Firebase Authentication.

Integrating Firebase with Golang

In this section, you are going to setup your Golang app and the Firebase Admin SDK for Go.

Setting up your Go app

Create a project directory for your project files and navigate to it.

mkdir go-firebase-auth
cd go-firebase-auth

Use the following command to initialize a go.mod file:

go mod init go-firebase-auth

The go.mod file will keep track of your app dependencies.

Setting up the folders and files of your Go app

In your project's working directory, create two folders, static and middleware.

The static folder will contain your HTML pages for interacting with your Golang server.

Inside the static folder, create three HTML files: index.html, signup.html, and premium.html.

The middleware folder will contain a middleware function for verifying tokens sent by the client.

Inside of the middleware folder, create a file: auth.go

Finally, in the root of your app's directory, create a main.go file. This main.go file will be the entry point of your app.

If you followed the steps correctly, your Go app folder structure should look like this:

7

Installing Firebase Admin SDK for Go

The Firebase Admin SDK for Go allows you to interact with Firebase features, such as Authentication, from your Golang app.

Run the following code in your terminal to install the Firebase Admin Go SDK:

    go get firebase.google.com/go/v4@latest

Setting Up the Firebase Admin SDK

To interact with the Firebase Admin Go SDK, you need to generate your service account key in the Firebase Developer Console.

In your project's overview page, click on the settings icon (highlighted below) and select Project settings. Then select the Service account tab.

8

Scroll down and click on Generate new private key to download your JSON credential file. Save the JSON credential file in the root of your project's directory as you will be using the file to initialize Firebase in your Golang app.

9

Authentication Flow

Before we go into building out the application, it's important understand the flow of our application.

Here's a breakdown of our application's flow:

When a user signs in/up in the client-side of our application, we will get the ID token of the user using the getIdToken function property on the user object. The user is then redirected to the Premium page, with the ID token added as a query parameter.

In the Go backend, we will retrieve and verify the ID Token from the query parameter in the client's request. If the verification is successful, the user is allowed access to the Premium page. Else, the user is denied access to the Premium page.

Now you have an understanding of our application flow, let's get started with the implementation.

Setting up the client of the application

In this section, you will set up the client-side of the application you will use to communicate your Golang app.

In the index.html file, paste the following code:

<!-- index.html -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Home page</title>
  </head>
  <body>
    <h1>Welcome to Firebase Authentication with Golang</h1>
    <h2>Login to access premium content</h2>
    <form action="">
      <label for="email">Email</label>
      <input type="email" name="email" id="email" />
      <label for="password">Password</label>
      <input type="password" name="password" id="password" />
      <button type="submit" id="signin">Sign In</button>
    </form>
    <p>Or <a href="signup.html">Sign up</a></p>
    <script type="module">
      // Import the functions you need from the SDKs you need
      import { initializeApp } from "https://www.gstatic.com/firebasejs/10.12.2/firebase-app.js";
      import {
        getAuth,
        signInWithEmailAndPassword,
        signInAnonymously,
        onAuthStateChanged,
      } from "https://www.gstatic.com/firebasejs/10.12.2/firebase-auth.js";
      // TODO: Add SDKs for Firebase products that you want to use
      // https://firebase.google.com/docs/web/setup#available-libraries

      // Your web app's Firebase configuration
      const firebaseConfig = {
        apiKey: "YOUR API KEY",
        authDomain: "YOUR AUTH DOMAIN",
        projectId: "PROJECT ID",
        storageBucket: "YOUR STORAGE BUCKET",
        messagingSenderId: "YOUR SENDER ID",
        appId: "YOUR APP ID",
      };

      // Initialize Firebase
      const app = initializeApp(firebaseConfig);
      const auth = getAuth(app);

      function login(e) {
        e.preventDefault();
        const email = document.querySelector("#email").value;
        const password = document.querySelector("#password").value;
        signInWithEmailAndPassword(auth, email, password)
          .then((userCredential) => {
            const user = userCredential.user;
            user
              .getIdToken()
              .then((idToken) => {
                // redirect to the premium page
                window.location.href = `http://localhost:8080/premium?auth-token=${idToken}`;
              })
              .catch((err) => {
                alert("Failed to authorize token");
                window.location.href = 'http://localhost:8080/';
                console.error("Token error: ", err);
              });
          })
          .catch((err) => {
            console.log("Sign-in error: ", err);
          });

        clearForm();
      }

      function clearForm() {
        document.querySelector("#email").value = "";
        document.querySelector("#password").value = "";
      }

      document.getElementById("signin").onclick = login;

      // checking if the user is logged in
      onAuthStateChanged(auth, (user) => {
        if (user) {
          console.log(user);
        } else {
          console.log("No user signed in");
        }
      });
    </script>
  </body>
</html>

Let's understand the above code in detail:

The HTML structure sets up a basic web page with a form for a user to login.

In the script tag, the Firebase SDK modules for app initialization and authentication are imported.

The firebaseConfig object holds the configuration values for the Firebase project, such as the API key, auth domain, project ID, storage bucket, messaging sender ID, and app ID.

The initializeApp function initializes the Firebase application with the configuration values provided in the firebaseConfig object.

The getAuth function initializes and returns the Firebase Authentication instance using the initialized app.

The login function handles the form submission for user login:

  • It prevents the default form submission behavior.
  • It retrieves the email and password input values from the form.
  • It attempts to sign in with the provided email and password using the signInWithEmailAndPassword function.
  • If the sign-in is successful, it retrieves the ID token of the authenticated user.
  • It then redirects the user to a premium content page with the ID token included in the query parameters.
  • If there is an error in retrieving the ID token, it alerts the user and redirects them back to the home page.
  • If there is a sign-in error, it logs the error to the console.
  • It clears the form inputs after submission by calling the clearForm function.

The clearForm function resets the email and password input fields.

The login function is assigned to the onclick event of the Sign in button.

The onAuthStateChanged function listens for changes in the authentication state:

  • If a user is signed in, it logs the user information to the console.
  • If no user is signed in, it logs a message indicating that no user is signed in.

Assuming there's no error in creating the Sign up page, your UI should look like this:

10

In the signup.html file, paste in the following code:

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Sign Up</title>
  </head>
  <body>
    <h1>Welcome to Firebase Authentication with Golang</h1>
    <h2>Register to access premium content</h2>
    <form action="">
      <label for="name">Full Name</label>
      <input type="text" name="name" id="name" />
      <label for="email">Email</label>
      <input type="email" name="email" id="email" />
      <label for="password">Password</label>
      <input type="password" name="password" id="password" />
      <button type="submit" id="signup">Sign up</button>
    </form>
    <p>Already have an account? <a href="index.html">Sign in</a></p>
    <p id="error"></p>
    <script type="module">
      // Import the functions you need from the SDKs you need
      import { initializeApp } from "https://www.gstatic.com/firebasejs/10.12.2/firebase-app.js";
      import {
        getAuth,
        createUserWithEmailAndPassword,
        onAuthStateChanged,
      } from "https://www.gstatic.com/firebasejs/10.12.2/firebase-auth.js";
      // TODO: Add SDKs for Firebase products that you want to use
      // https://firebase.google.com/docs/web/setup#available-libraries

      // Your web app's Firebase configuration
      const firebaseConfig = {
        apiKey: "YOUR API KEY",
        authDomain: "YOUR AUTH DOMAIN",
        projectId: "PROJECT ID",
        storageBucket: "YOUR STORAGE BUCKET",
        messagingSenderId: "YOUR SENDER ID",
        appId: "YOUR APP ID",
      };

      // Initialize Firebase
      const app = initializeApp(firebaseConfig);
      const auth = getAuth(app);

      function signUp(e) {
        e.preventDefault();

        const email = document.querySelector("#email").value;
        const password = document.querySelector("#password").value;

        createUserWithEmailAndPassword(auth, email, password)
          .then((userCredential) => {
            // console.log(userCredential.user);
            const user = userCredential.user;
            console.log(user);
            user
              .getIdToken()
              .then((idToken) => {
                // redirect to premium page
                window.location.href = `http://localhost:8080/premium?auth-token=${idToken}`;
              })
              .catch((err) => {
                document.querySelector(
                  "#error"
                ).textContent = `An error occured: ${err.message}`;
                window.location.href = "http://localhost:8080/signup.html";
                console.error(err.code, err.message);
              });
          })
          .catch((err) => {
            document.querySelector(
              "#error"
            ).textContent = `An error occured: ${err.message}`;
            console.error(err.code, err.message);
          });

        clearForm();
      }

      document.getElementById("signup").onclick = signUp;

      function clearForm() {
        document.querySelector("#email").value = "";
        document.querySelector("#password").value = "";
      }
    </script>
  </body>
</html>

Let's understand the code above in detail:

In this HTML structure, the web page is set up for user registration instead of login.

In the script tag, we import the Firebase SDK modules for app initialization and authentication, similar to the previous snippet, but with a focus on user creation.

The createUserWithEmailAndPassword function is imported and used to handle user sign-up.

The signUp function handles the form submission for user registration:

  • It prevents the default form submission behavior.
  • It retrieves the email and password input values from the form.
  • It attempts to create a new user with the provided email and password using the createUserWithEmailAndPassword function.
  • If the sign-up is successful, it retrieves the ID token of the newly created user.
  • It then redirects the user to a premium content page with the ID token included in the query parameters.
  • If there is an error in retrieving the ID token or during sign-up, it displays the error message in the #error element and logs the error to the console.
  • It clears the form inputs after submission by calling the clearForm function.

The signup button has an onclick event listener attached to it, which triggers the signUp function when the button is clicked.

The clearForm function resets the email and password input fields, similar to the previous snippet.

Assuming there's no error in creating the Sign up page, your UI should look like this:

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:::info Remember to replace the firebaseConfig object with your configuration details obtained during the registration of your app. :::

In the premium.html file, paste in the following code:

<!-- premium.html -->
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Premium Page</title>
</head>
<body>
    <h1>Welcome to the premium page</h1>
    <p>Your token is verified and you are now viewing the premium page</p>
</body>
</html>

This HTML structure sets up a simple web page that serves as a premium content page.

Well done! You have set up your client. In the next section, you will implement authentication in your Golang app.

Implementing Authentication in Golang

In this section, you will create your Golang server and implement Firebase Authentication in the Golang app.

Creating a Golang Server

In the main.go, paste in the code:

// main.go

import (
	"context"
	"fmt"
	"html/template"
	"log"
	"net/http"
)
package main

func main(){
    fileServer := http.FileServer(http.Dir("./static"))
    http.Handle("/", fileServer)

    http.Handle("/premium", premiumHandler)

    fmt.Printf("Starting server at port 8080\n")
    if err := http.ListenAndServe(":8080", nil); err != nil {
	    log.Fatalf("Error creating server: %v\n", err)
    }
}

Let's understand the above code:

The main function sets up an HTTP server to serve static files and handle requests to a premium content page.

The fileServer variable is initialized with a file server that serves static files from the ./static directory.

The http.Handle("/", fileServer) function registers the file server to handle all requests to the root URL (/).

The http.Handle("/premium", premiumHandler) function registers a handler function premiumHandler to handle requests to the /premium URL.

The fmt.Printf("Starting server at port 8080\n") statement prints a message to the console indicating that the server is starting on port 8080.

The http.ListenAndServe(":8080", nil) function starts the HTTP server on port 8080. If the server fails to start, it logs a fatal error and exits using log.Fatalf.

Initializing Firebase in the Golang server

Add the following code to the top most part of the main function in the main.go file.

// main.go

package main

import (
	"context"
	"fmt"
	"html/template"
	"log"
	"net/http"

	firebase "firebase.google.com/go"
	"google.golang.org/api/option"
)

func main() {
	opt := option.WithCredentialsFile("credentials.json")
	app, err := firebase.NewApp(context.Background(), nil, opt)
	if err != nil {
		log.Fatalf("Error initializing app: %v\n", err)
	}
    
	client, err := app.Auth(context.Background())
	if err != nil {
		log.Fatalf("Error creating client: %v\n", err)
	}
    
    // rest of function
}

The opt := option.WithCredentialsFile("credentials.json") line creates an option to use the JSON credentials file, you downloaded earlier, for Firebase. Replace credentials.json with the name of your JSON credentials file.

The app, err := firebase.NewApp(context.Background(), nil, opt) line initializes a new Firebase app with the provided credentials. If there's an error, it logs a fatal error and exits.

The client, err := app.Auth(context.Background()) line creates a new Firebase Auth client. If there's an error, it logs a fatal error and exits. This Firebase Auth client will be used to verify the ID Token from the incoming request.

Remember to import the necessary packages: firebase firebase.google.com/go and google.golang.org/api/option. If you are using VS Code, the packages will be automatically imported.

Next, your are going to create the premiumHandler function to authenticate and authorize user requests.

Handling Authentication Requests

Just above the http.Handle("/", fileServer) line, add the following code:

// main.go
premiumHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

		token := r.Context().Value("verifiedToken")
		if token == "" {
			http.Error(w, "Unauthorized", http.StatusUnauthorized)
			return
		}

		tmpl, err := template.ParseFiles("static/premium.html")
		if err != nil {
			http.Error(w, "Internal Server Error", http.StatusInternalServerError)
			log.Printf("Error parsing templates: %v\n", err)
			return
		}

		data := map[string]interface{}{
			"Token": token,
		}

		tmpl.Execute(w, data)

Let's understand the above code in detail:

You defined the premiumHandler function to handle requests to the /premium URL.

The token := r.Context().Value("verifiedToken") line retrieves the verifiedToken from the request context.

The if token == "" { http.Error(w, "Unauthorized", http.StatusUnauthorized); return } block checks if the token is empty. If the token is empty, it responds with an "Unauthorized" error and stops further execution.

The tmpl, err := template.ParseFiles("static/premium.html") line parses the premium.html template file from the static directory.

The if err != nil { http.Error(w, "Internal Server Error", http.StatusInternalServerError); log.Printf("Error parsing templates: %v\n", err); return } block checks for errors in parsing the template. If there is an error, it responds with an "Internal Server Error" and logs the error.

The data := map[string]interface{}{"Token": token} line prepares data to be passed to the template, in this case, the verified token.

The tmpl.Execute(w, data) line executes the template with the provided data and writes the result to the response.

With this change, your main.go file should look this:

// main.go
package main

import (
	"context"
	"fmt"
	"html/template"
	"log"
	"net/http"

	firebase "firebase.google.com/go"
	"google.golang.org/api/option"
)

func main() {
	opt := option.WithCredentialsFile("credentials.json")
	app, err := firebase.NewApp(context.Background(), nil, opt)
	if err != nil {
		log.Fatalf("Error initializing app: %v\n", err)
	}

	client, err := app.Auth(context.Background())
	if err != nil {
		log.Fatalf("Error creating client: %v\n", err)
	}

	premiumHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

		token := r.Context().Value("verifiedToken")
		if token == "" {
			http.Error(w, "Unauthorized", http.StatusUnauthorized)
			return
		}

		tmpl, err := template.ParseFiles("static/premium.html")
		if err != nil {
			http.Error(w, "Internal Server Error", http.StatusInternalServerError)
			log.Printf("Error parsing templates: %v\n", err)
			return
		}

		data := map[string]interface{}{
			"Token": token,
		}

		tmpl.Execute(w, data)

	fileServer := http.FileServer(http.Dir("./static"))
	http.Handle("/", fileServer)

	http.Handle("/premium", premiumHandler)

	fmt.Printf("Starting server at port 8080\n")
	if err := http.ListenAndServe(":8080", nil); err != nil {
		log.Fatalf("Error creating server: %v\n", err)
	}
}

Now you have you created the premiumHandler function, the next step is to create a middleware.

Creating middleware

Middleware is a function that intercepts HTTP requests and responses in a web application, allowing you to perform common tasks such as logging, authentication, and authorization before the request reaches the final handler.

In the context of our Go application with Firebase Authentication, middleware will be used to verify the user's authentication token before granting access to premium content. The middleware function will extract the token from the request, validate it using the Firebase Auth client, and then pass the verified token to the request context.

Navigate to the auth.go file in the middleware and paste the following code:

// middleware/auth.go
package middleware

import (
	"context"
	"log"
	"net/http"
	"net/url"

	"firebase.google.com/go/auth"
)

func AuthMiddleWare(client *auth.Client) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			// parse Query parameters
			params, err := url.ParseQuery(r.URL.RawQuery)
			if err != nil {
				http.Error(w, "Bad Request", http.StatusBadRequest)
				// log.Fatalf("")
				return
			}

			idToken := params.Get("auth-token")
			if idToken == "" {
				http.Error(w, "Unauthorized", http.StatusUnauthorized)
				return
			}

			// verify ID token
			verifiedToken, err := client.VerifyIDToken(context.Background(), idToken)
			if err != nil {
				http.Error(w, "Unauthorized", http.StatusUnauthorized)
				log.Printf("Error verifying token: %v\n", err)
			}

			// Add token to the request context
			ctx := context.WithValue(r.Context(), "verifiedToken", verifiedToken)
			next.ServeHTTP(w, r.WithContext(ctx))
		})
	}
}

Let's understand the above code in detail:

The AuthMiddleWare function is defined to intercept incoming HTTP requests, verify the Firebase authentication token, and pass the verified token in the request context to the next handler.

The func AuthMiddleWare(client *auth.Client) func(http.Handler) http.Handler line declares the middleware function, which takes a Firebase Auth client as a parameter and returns a middleware handler function.

The return func(next http.Handler) http.Handler line returns a handler function that wraps the next handler.

The return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { ... }) line creates and returns an HTTP handler function to process each request.

Query Parameter Parsing: params, err := url.ParseQuery(r.URL.RawQuery) parses the query parameters from the URL.

if err != nil { http.Error(w, "Bad Request", http.StatusBadRequest); return } checks for parsing errors and responds with a "Bad Request" error if any.

Token Extraction: idToken := params.Get("auth-token") retrieves the auth-token parameter from the query string.

if idToken == "" { http.Error(w, "Unauthorized", http.StatusUnauthorized); return } checks if the token is missing and responds with an "Unauthorized" error if the token is missing.

Token Verification: verifiedToken, err := client.VerifyIDToken(context.Background(), idToken) verifies the ID token using the Firebase Auth client.

if err != nil { http.Error(w, "Unauthorized", http.StatusUnauthorized); log.Printf("Error verifying token: %v\n", err); return } handles verification errors, responds with an "Unauthorized" error, and logs the error.

Context Update: ctx := context.WithValue(r.Context(), "verifiedToken", verifiedToken) adds the verified token to the request context.

next.ServeHTTP(w, r.WithContext(ctx)) passes the request with the updated context to the next handler.

After creating the middleware function, import and use the middleware function in the main.go file.

package main
package main

import (
	"app/middleware"
	"context"
	"fmt"
	"html/template"
	"log"
	"net/http"

	firebase "firebase.google.com/go"
	"google.golang.org/api/option"
)

func main() {
	opt := option.WithCredentialsFile("credentials.json")
	app, err := firebase.NewApp(context.Background(), nil, opt)
	if err != nil {
		log.Fatalf("Error initializing app: %v\n", err)
	}

	client, err := app.Auth(context.Background())
	if err != nil {
		log.Fatalf("Error creating client: %v\n", err)
	}

	premiumHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

		token := r.Context().Value("verifiedToken")
		if token == "" {
			http.Error(w, "Unauthorized", http.StatusUnauthorized)
			return
		}

		tmpl, err := template.ParseFiles("static/premium.html")
		if err != nil {
			http.Error(w, "Internal Server Error", http.StatusInternalServerError)
			log.Printf("Error parsing templates: %v\n", err)
			return
		}

		data := map[string]interface{}{
			"Token": token,
		}

		tmpl.Execute(w, data)

	fileServer := http.FileServer(http.Dir("./static"))
	http.Handle("/", fileServer)

	http.Handle("/premium", middleware.AuthMiddleWare(client)(premiumHandler))

	fmt.Printf("Starting server at port 8080\n")
	if err := http.ListenAndServe(":8080", nil); err != nil {
		log.Fatalf("Error creating server: %v\n", err)
	}
}

The middleware package is imported to access the AuthMiddleWare function.

The /premium route is protected by wrapping the premiumHandler with the AuthMiddleWare function, ensuring that only requests with a verified token can access this route.

Testing the app

In this section, you are going to test your application.

In your terminal, run the following command to start up the server:

go run main.go

After running the command, you server will be started at port 8080

Starting server at port 8080

In your web browser, type in the URL: localhost:8080. You should be met with the index.html page:

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Since you don't have a user, navigate to the Sign up page by clicking on the sign up link. You will redirected to the Sign up page.

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Input the necessary details and click on the Sign up button. After registering the user, the user is automatically redirected to the Premium page. This is because, Firebase automatically signs in users after their creation.

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To test that the login page is working, navigate to the home page and refresh the page. Then, input the email and password of the user you previously created.

After clicking on the Sign in button, you should be redirected to the Premium page.

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Congratulations! You have implemented Firebase Authentication in your Golang app.

Troubleshooting

When integrating Firebase Authentication with your Golang application, you may encounter several common issues. Below are some troubleshooting tips to help you resolve these issues effectively:

  1. Firebase Configuration Issues:

    • Credentials File: Ensure that your JSON credentials file is correctly placed and accessible by your application. Verify that the path provided in option.WithCredentialsFile("credentials.json") matches the actual file location.

    • Firebase Project Configuration: Double-check that your Firebase project configuration (API key, project ID, etc.) in firebaseConfig matches the settings in your Firebase project console.

  2. Middleware and Authentication Errors:

    • Token Verification: If users are experiencing frequent "Unauthorized" errors even with valid tokens, check the token verification process in your middleware (AuthMiddleWare function). Ensure that tokens are correctly extracted and verified using Firebase's VerifyIDToken method.

    • Error Logging: Implement comprehensive error logging within your middleware and handlers (premiumHandler) to capture and diagnose token verification failures or other authentication-related issues.

  3. HTTP Handler and Template Errors:

    • Template Parsing: If your application fails to parse or render templates (template.ParseFiles), verify the file path and ensure that the template files (premium.html, etc.) exist in the specified directory (static directory in this case).

    • HTTP Response Handling: Use appropriate HTTP error codes (http.StatusInternalServerError, http.StatusBadRequest, etc.) and error messages (http.Error) to provide meaningful feedback to users and debug errors effectively.

  4. Firebase SDK and API Compatibility:

    • SDK Versions: Ensure that the Firebase SDK versions (firebase.google.com/go and related libraries) in your application are compatible with each other and with the Firebase services you are using (Authentication). Check for updates and compatibility issues regularly.
  5. Network and Connectivity Issues:

    • Local Development Environment: If running into issues during local development (http.ListenAndServe(":8080")), ensure that your local server environment (ports, network settings) is correctly configured and not blocked by firewalls or network restrictions.
  6. Logging and Debugging:

    • Verbose Logging: Increase verbosity in your logging (log.Printf, log.Fatalf) during development and testing phases to capture detailed information about each request, authentication attempt, and potential errors.

    • Debugging Tools: Use debugging tools and techniques (such as Go's fmt.Printf statements, log package, or third-party debugging tools) to inspect variables, trace code execution, and pinpoint the root cause of issues.

Conclusion

In this article, you learned the essential steps to connect Firebase Authentication to a Golang application, covering the implementation of user registration and login using the Firebase Admin Go SDK.

If you are interested in learning more about Firebase Authentication with Go, I recommend these resources:

You can find this projects' code in this GitHub repository.

Firebase Authentication is just one among the suite of services offered by Firebase. Other services include: Cloud Firestore, Cloud Functions, Realtime Databases, Gemini integration, etc.. You are welcome to try out these services to build scalable, secure, performant, and feature-rich applications.