{"componentChunkName":"component---src-pages-markdown-remark-fields-slug-js","path":"/engineering/google-authentication-with-golang-and-goth/","result":{"data":{"markdownRemark":{"id":"3e648e6e-dd61-5188-8294-809a2a6a11cd","excerpt":"In this blog, we’ll be implementing authentication via Google in a Go web application. For this, we’ll be using Goth - Multi-Provider Authentication Package for…","html":"

In this blog, we’ll be implementing authentication via Google in a Go web application. For this, we’ll be using Goth - Multi-Provider Authentication Package for Go

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Before You Get Started

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This tutorial assumes you have:

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Step 1: Create a Google client ID and client secret

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We can create a client ID and client secret using its Google API Console. You need to follow below steps once you open Google API Console

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Note: If Google doesn't support http://localhost:3000, then use http://127.0.0.1:3000

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Step 2: Initialize a Go project using Go modules

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First in an empty folder run the below command

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go mod init googleauth
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go mod init creates a new go.mod file and automatically imports dependencies when you will run go program

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Step 3: Writing golang server code to accept web requests

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Create a file main.go in the root folder of your app and add the following code:

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A small description for packages used in below code

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package main\n\nimport (\n  "fmt"\n  "html/template"\n  "net/http"\n  \n\n  "log"\n\n  "github.com/gorilla/pat"\n  "github.com/markbates/goth"\n  "github.com/markbates/goth/gothic"\n  "github.com/markbates/goth/providers/google"\n  "github.com/gorilla/sessions"\n)\n\n\nfunc main() {\n  \n  key := "Secret-session-key"  // Replace with your SESSION_SECRET or similar\n  maxAge := 86400 * 30  // 30 days\n  isProd := false       // Set to true when serving over https\n\n  store := sessions.NewCookieStore([]byte(key))\n  store.MaxAge(maxAge)\n  store.Options.Path = "/"\n  store.Options.HttpOnly = true   // HttpOnly should always be enabled\n  store.Options.Secure = isProd\n\n  gothic.Store = store\n\n  goth.UseProviders(\n    google.New("our-google-client-id", "our-google-client-secret", "http://localhost:3000/auth/google/callback", "email", "profile"),\n  )\n\n  p := pat.New()\n  p.Get("/auth/{provider}/callback", func(res http.ResponseWriter, req *http.Request) {\n\n    user, err := gothic.CompleteUserAuth(res, req)\n    if err != nil {\n      fmt.Fprintln(res, err)\n      return\n    }\n    t, _ := template.ParseFiles("templates/success.html")\n    t.Execute(res, user)\n  })\n\n  p.Get("/auth/{provider}", func(res http.ResponseWriter, req *http.Request) {\n    gothic.BeginAuthHandler(res, req)\n  })\n\n  p.Get("/", func(res http.ResponseWriter, req *http.Request) {\n    t, _ := template.ParseFiles("templates/index.html")\n    t.Execute(res, false)\n  })\n  log.Println("listening on localhost:3000")\n  log.Fatal(http.ListenAndServe(":3000", p))\n}
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Note: The callback URL in google.New should be the same as used in the google app configuration.

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If it is hard to understand the code, Here is the description of all the routes used in the code mentioned above

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Step 4: Creating a Login and Profile page

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Create an html file under path templates/index.html, it will render into a nice looking social login page:

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<!-- templates/index.html -->\n<!doctype html>\n<html>\n<head>\n    <title>Google SignIn</title>\n    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css"> <!-- load bulma css -->\n    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css"> <!-- load fontawesome -->\n    <style>\n        body        { padding-top:70px; }\n    </style>\n</head>\n<body>\n<div class="container">\n    <div class="jumbotron text-center text-success">\n        <h1><span class="fa fa-lock"></span> Social Authentication</h1>\n        <p>Login or Register with:</p>\n        <a href="/auth/google" class="btn btn-danger"><span class="fa fa-google"></span> SignIn with Google</a>\n    </div>\n</div>\n</body>\n</html>
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After it we will create an Html file under path templates/success.html, it will be used to show the user profile information we will get after authenticated by google

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<!-- templates/success.html -->\n<!doctype html>\n<html>\n  <head>\n    <title>Google SignIn</title>\n    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css"> <!-- load bulma css -->\n    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css"> <!-- load fontawesome -->\n      <style>\n          body        { padding-top:70px; }\n      </style>\n  </head>\n  <body>\n    <div class="container">\n      <div class="jumbotron">\n          <h1 class="text-success  text-center"><span class="fa fa-user"></span> Profile Information</h1>\n          <div class="row">\n            <div class="col-sm-6">\n                <div class="well">\n                        <p>\n                            <strong>Id</strong>: {{.UserID}}<br>\n                            <strong>Email</strong>: {{.Email}}<br>\n                            <strong>Name</strong>: {{.Name}}\n                        </p>\n                </div>\n            </div>\n        </div>\n      </div>\n    </div>\n  </body>\n</html>
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Note: Here we are also using bootstrap and font-awesome css to make our web pages look good.

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We have finished building our social login page, let's run the application by below command

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go run main.go
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Once our server is running, we can see our social login page on http://localhost:3000/

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\"Social

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We need to click on SignIn with Google button, which will redirect us to the google login page.

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\"Google

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After login with our google credentials, it will redirect back to our application and on the success page, we can see the details of the logged-in user and can save this detail in a database for future use also.

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\"Social

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As we have seen it is fairly easy to build a google social authentication system with Go language and Goth package, You can found the complete code used in this tutorial on our Github Repo

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