Introduction
This tutorial demonstrates how to build a "Login with GitHub" button for a website. The website will use a GitHub App to generate a user access token via the web application flow. Then, the website uses the user access token to make API requests on behalf of the authenticated user.
This tutorial uses Ruby, but you can use the web application flow with any programming language that is used for web development.
About web application flow and user access tokens
Your app should use a user access token if you want to attribute the app's actions to a user. For more information, see "Authenticating with a GitHub App on behalf of a user."
There are two ways to generate a user access token for a GitHub App: web application flow and device flow. If your app has access to a web interface, you should use web application flow. If your app does not have access to a web interface, you should use device flow instead. For more information, see "Generating a user access token for a GitHub App" and "Building a CLI with a GitHub App."
Prerequisites
This tutorial assumes that you have already registered a GitHub App. For more information about registering a GitHub App, see "Registering a GitHub App."
Before following this tutorial, you must set a callback URL for your app. This tutorial uses a local Sinatra server with the default URL of http://localhost:4567
. For example, to work with the default URL for a local Sinatra application, your callback URL can be http://localhost:4567/github/callback
. Once you are ready to deploy your app, you can change the callback URL to use your live server address. For more information about updating the callback URL for your app, see "Modifying a GitHub App registration" and "About the user authorization callback URL."
This tutorial assumes that you have a basic understanding of Ruby and of the Ruby template system, ERB. For more information, see Ruby and ERB.
Install dependencies
This tutorial uses the Ruby gem, Sinatra, to create a web application with Ruby. For more information, see the Sinatra README.
This tutorial uses the Ruby gem, dotenv, to access values stored in a .env
file. For more information, see the dotenv README.
To follow this tutorial, you must install the Sinatra and dotenv gems in your Ruby project. For example, you can do this with Bundler:
-
If you don't already have Bundler installed, run the following command in your terminal:
gem install bundler
-
If you don't already have a Gemfile for your app, run the following command in your terminal:
bundle init
-
If you don't already have a Gemfile.lock for your app, run the following command in your terminal:
bundle install
-
Install the gems by running the following commands in your terminal:
bundle add sinatra
bundle add dotenv
Store the client ID and client secret
This tutorial will show you how to store the client ID and client secret in environment variables and access them with ENV.fetch
. When you deploy your app, you will want to change how you store the client ID and client secret. For more information, see "Securely store your client secret."
-
In the upper-right corner of any page on GitHub, click your profile photo.
-
Navigate to your account settings.
- For an app owned by a personal account, click Settings.
- For an app owned by an organization:
- Click Your organizations.
- To the right of the organization, click Settings.
-
In the left sidebar, click Developer settings.
-
In the left sidebar, click GitHub Apps.
-
Next to the GitHub App that you want to work with, click Edit.
-
On the app's settings page, find the client ID for your app. You will add it to a
.env
file in a following step. Note that the client ID is different from the app ID. -
On the app's settings page, click Generate a new client secret. You will add the client secret to a
.env
file in a following step. -
Create a file called
.env
at the same level as yourGemfile
. -
If your project doesn't already have a
.gitignore
file, create a.gitignore
file at the same level as yourGemfile
. -
Add
.env
to your.gitignore
file. This will prevent you from accidentally committing your client secret. For more information about.gitignore
files, see "Ignoring files." -
Add the following contents to your
.env
file. ReplaceYOUR_CLIENT_ID
with the client ID of your app. ReplaceYOUR_CLIENT_SECRET
with the client secret for your app.CLIENT_ID="YOUR_CLIENT_ID" CLIENT_SECRET="YOUR_CLIENT_SECRET"
Add code to generate a user access token
To get a user access token, you first need to prompt the user to authorize your app. When a user authorizes your app, they are redirected to the callback URL for your app. The request to the callback URL includes a code
query parameter. When your app gets a request to serve that callback URL, you can exchange the code
parameter for a user access token.
These steps lead you through writing code to generate a user access token. To skip ahead to the final code, see "Full code example."
-
In the same directory as your
.env
file, create a Ruby file to hold the code that will generate a user access token. This tutorial will name the fileapp.rb
. -
At the top of
app.rb
, add these dependencies:Ruby require "sinatra" require "dotenv/load" require "net/http" require "json"
require "sinatra" require "dotenv/load" require "net/http" require "json"
The
sinatra
anddotenv/load
dependencies use the gems that you installed earlier.net/http
andjson
are part of the Ruby standard library. -
Add the following code to
app.rb
, to get your app's client ID and client secret from your.env
file.Ruby CLIENT_ID = ENV.fetch("CLIENT_ID") CLIENT_SECRET = ENV.fetch("CLIENT_SECRET")
CLIENT_ID = ENV.fetch("CLIENT_ID") CLIENT_SECRET = ENV.fetch("CLIENT_SECRET")
-
Add the following code to
app.rb
to display a link that will prompt users to authenticate your app.Ruby get "/" do link = '<a href="https://github.com/login/oauth/authorize?client_id=<%= CLIENT_ID %>">Login with GitHub</a>' erb link end
get "/" do link = '<a href="https://github.com/login/oauth/authorize?client_id=<%= CLIENT_ID %>">Login with GitHub</a>' erb link end
-
Add the following code to
app.rb
to handle requests to your app's callback URL and get thecode
parameter from the request. ReplaceCALLBACK_URL
with the callback URL for your app, minus the domain. For example, if your callback URL ishttp://localhost:4567/github/callback
, replaceCALLBACK_URL
with/github/callback
.Ruby get "CALLBACK_URL" do code = params["code"] render = "Successfully authorized! Got code #{code}." erb render end
get "CALLBACK_URL" do code = params["code"] render = "Successfully authorized! Got code #{code}." erb render end
Currently, the code just renders a message along with the
code
parameter. The following steps will expand this code block. -
Optionally, check your progress:
app.rb
now looks like this, whereCALLBACK_URL
is the callback URL for your app, minus the domain:Ruby require "sinatra" require "dotenv/load" require "net/http" require "json" CLIENT_ID = ENV.fetch("CLIENT_ID") CLIENT_SECRET = ENV.fetch("CLIENT_SECRET") get "/" do link = '<a href="https://github.com/login/oauth/authorize?client_id=<%= CLIENT_ID %>">Login with GitHub</a>' erb link end get "CALLBACK_URL" do code = params["code"] render = "Successfully authorized! Got code #{code}." erb render end
require "sinatra" require "dotenv/load" require "net/http" require "json" CLIENT_ID = ENV.fetch("CLIENT_ID") CLIENT_SECRET = ENV.fetch("CLIENT_SECRET") get "/" do link = '<a href="https://github.com/login/oauth/authorize?client_id=<%= CLIENT_ID %>">Login with GitHub</a>' erb link end get "CALLBACK_URL" do code = params["code"] render = "Successfully authorized! Got code #{code}." erb render end
-
In your terminal, from the directory where
app.rb
is stored, runruby app.rb
. A local Sinatra server should start. -
In your browser, navigate to
http://localhost:4567
. You should see a link with the text "Login with GitHub". -
Click on the "Login with GitHub" link.
If you have not authorized the app, clicking on the link should take you to
https://github.com/login/oauth/authorize?client_id=CLIENT_ID
, whereCLIENT_ID
is the client ID of your app. This is a GitHub page that prompts users to authorize your app. If you click the button to authorize your app, you will go to the callback URL for your app.If you previously authorized your app and the authorization has not been revoked, you will skip the authorization prompt and go directly to the callback URL instead. You can revoke your previous authorization if you want to see the authorization prompt. For more information, see "Reviewing and revoking authorization of GitHub Apps."
-
The callback URL page, reached by clicking the "Login with GitHub" link and then authorizing the app if prompted to do so, should display the text similar to "Successfully authorized! Got code agc622abb6135be5d1f2."
-
In your terminal where Sinatra is running, stop the server by entering Ctrl+C.
-
-
Replace the content of
app.rb
with the following code, whereCALLBACK_URL
is the callback URL for your app, minus the domain.This code adds logic to exchange the
code
parameter for a user access token:- The
parse_response
function parses the response from the GitHub API. - The
exchange_code
function exchanges thecode
parameter for a user access token. - The handler for the callback URL request now calls
exchange_code
to exchange the code parameter for a user access token. - The callback page now shows text to indicate that a token was generated. If the token generation was not successful, the page will indicate that failure.
Ruby require "sinatra" require "dotenv/load" require "net/http" require "json" CLIENT_ID = ENV.fetch("CLIENT_ID") CLIENT_SECRET = ENV.fetch("CLIENT_SECRET") def parse_response(response) case response when Net::HTTPOK JSON.parse(response.body) else puts response puts response.body {} end end def exchange_code(code) params = { "client_id" => CLIENT_ID, "client_secret" => CLIENT_SECRET, "code" => code } result = Net::HTTP.post( URI("https://github.com/login/oauth/access_token"), URI.encode_www_form(params), {"Accept" => "application/json"} ) parse_response(result) end get "/" do link = '<a href="https://github.com/login/oauth/authorize?client_id=<%= CLIENT_ID %>">Login with GitHub</a>' erb link end get "CALLBACK_URL" do code = params["code"] token_data = exchange_code(code) if token_data.key?("access_token") token = token_data["access_token"] render = "Successfully authorized! Got code #{code} and exchanged it for a user access token ending in #{token[-9..-1]}." erb render else render = "Authorized, but unable to exchange code #{code} for token." erb render end end
require "sinatra" require "dotenv/load" require "net/http" require "json" CLIENT_ID = ENV.fetch("CLIENT_ID") CLIENT_SECRET = ENV.fetch("CLIENT_SECRET") def parse_response(response) case response when Net::HTTPOK JSON.parse(response.body) else puts response puts response.body {} end end def exchange_code(code) params = { "client_id" => CLIENT_ID, "client_secret" => CLIENT_SECRET, "code" => code } result = Net::HTTP.post( URI("https://github.com/login/oauth/access_token"), URI.encode_www_form(params), {"Accept" => "application/json"} ) parse_response(result) end get "/" do link = '<a href="https://github.com/login/oauth/authorize?client_id=<%= CLIENT_ID %>">Login with GitHub</a>' erb link end get "CALLBACK_URL" do code = params["code"] token_data = exchange_code(code) if token_data.key?("access_token") token = token_data["access_token"] render = "Successfully authorized! Got code #{code} and exchanged it for a user access token ending in #{token[-9..-1]}." erb render else render = "Authorized, but unable to exchange code #{code} for token." erb render end end
- The
-
Optionally, check your progress:
- In your terminal, from the directory where
app.rb
is stored, runruby app.rb
. A local Sinatra server should start. - In your browser, navigate to
http://localhost:4567
. You should see a link with the text "Login with GitHub". - Click on the "Login with GitHub" link.
- If prompted to do so, authorize your app.
- The callback URL page, reached by clicking the "Login with GitHub" link and then authorizing the app if prompted to do so, should display the text similar to "Successfully authorized! Got code 4acd44861aeda86dacce and exchanged it for a user access token ending in 2zU5kQziE."
- In your terminal where Sinatra is running, stop the server by entering Ctrl+C.
- In your terminal, from the directory where
-
Now that you have a user access token, you can use the token to make API requests on behalf of the user. For example:
Add this function to
app.rb
to get information about the user with the/user
REST API endpoint:Ruby def user_info(token) uri = URI("https://api.github.com/user") result = Net::HTTP.start(uri.host, uri.port, use_ssl: true) do |http| auth = "Bearer #{token}" headers = {"Accept" => "application/json", "Content-Type" => "application/json", "Authorization" => auth} http.send_request("GET", uri.path, nil, headers) end parse_response(result) end
def user_info(token) uri = URI("https://api.github.com/user") result = Net::HTTP.start(uri.host, uri.port, use_ssl: true) do |http| auth = "Bearer #{token}" headers = {"Accept" => "application/json", "Content-Type" => "application/json", "Authorization" => auth} http.send_request("GET", uri.path, nil, headers) end parse_response(result) end
Update the callback handler to call the
user_info
function and to display the user's name and GitHub login. Remember to replaceCALLBACK_URL
with the callback URL for your app, minus the domain.Ruby get "CALLBACK_URL" do code = params["code"] token_data = exchange_code(code) if token_data.key?("access_token") token = token_data["access_token"] user_info = user_info(token) handle = user_info["login"] name = user_info["name"] render = "Successfully authorized! Welcome, #{name} (#{handle})." erb render else render = "Authorized, but unable to exchange code #{code} for token." erb render end end
get "CALLBACK_URL" do code = params["code"] token_data = exchange_code(code) if token_data.key?("access_token") token = token_data["access_token"] user_info = user_info(token) handle = user_info["login"] name = user_info["name"] render = "Successfully authorized! Welcome, #{name} (#{handle})." erb render else render = "Authorized, but unable to exchange code #{code} for token." erb render end end
-
Check your code against the full code example in the next section. You can test your code by following the steps outlined in the "Testing" section below the full code example.
Full code example
This is the full code example that was outlined in the previous section.
Replace CALLBACK_URL
with the callback URL for your app, minus the domain. For example, if your callback URL is http://localhost:4567/github/callback
, replace CALLBACK_URL
with /github/callback
.
require "sinatra" require "dotenv/load" require "net/http" require "json" CLIENT_ID = ENV.fetch("CLIENT_ID") CLIENT_SECRET = ENV.fetch("CLIENT_SECRET") def parse_response(response) case response when Net::HTTPOK JSON.parse(response.body) else puts response puts response.body {} end end def exchange_code(code) params = { "client_id" => CLIENT_ID, "client_secret" => CLIENT_SECRET, "code" => code } result = Net::HTTP.post( URI("https://github.com/login/oauth/access_token"), URI.encode_www_form(params), {"Accept" => "application/json"} ) parse_response(result) end def user_info(token) uri = URI("https://api.github.com/user") result = Net::HTTP.start(uri.host, uri.port, use_ssl: true) do |http| auth = "Bearer #{token}" headers = {"Accept" => "application/json", "Content-Type" => "application/json", "Authorization" => auth} http.send_request("GET", uri.path, nil, headers) end parse_response(result) end get "/" do link = '<a href="https://github.com/login/oauth/authorize?client_id=<%= CLIENT_ID %>">Login with GitHub</a>' erb link end get "CALLBACK_URL" do code = params["code"] token_data = exchange_code(code) if token_data.key?("access_token") token = token_data["access_token"] user_info = user_info(token) handle = user_info["login"] name = user_info["name"] render = "Successfully authorized! Welcome, #{name} (#{handle})." erb render else render = "Authorized, but unable to exchange code #{code} for token." erb render end end
require "sinatra"
require "dotenv/load"
require "net/http"
require "json"
CLIENT_ID = ENV.fetch("CLIENT_ID")
CLIENT_SECRET = ENV.fetch("CLIENT_SECRET")
def parse_response(response)
case response
when Net::HTTPOK
JSON.parse(response.body)
else
puts response
puts response.body
{}
end
end
def exchange_code(code)
params = {
"client_id" => CLIENT_ID,
"client_secret" => CLIENT_SECRET,
"code" => code
}
result = Net::HTTP.post(
URI("https://github.com/login/oauth/access_token"),
URI.encode_www_form(params),
{"Accept" => "application/json"}
)
parse_response(result)
end
def user_info(token)
uri = URI("https://api.github.com/user")
result = Net::HTTP.start(uri.host, uri.port, use_ssl: true) do |http|
auth = "Bearer #{token}"
headers = {"Accept" => "application/json", "Content-Type" => "application/json", "Authorization" => auth}
http.send_request("GET", uri.path, nil, headers)
end
parse_response(result)
end
get "/" do
link = '<a href="https://github.com/login/oauth/authorize?client_id=<%= CLIENT_ID %>">Login with GitHub</a>'
erb link
end
get "CALLBACK_URL" do
code = params["code"]
token_data = exchange_code(code)
if token_data.key?("access_token")
token = token_data["access_token"]
user_info = user_info(token)
handle = user_info["login"]
name = user_info["name"]
render = "Successfully authorized! Welcome, #{name} (#{handle})."
erb render
else
render = "Authorized, but unable to exchange code #{code} for token."
erb render
end
end
Testing
This tutorial assumes that your app code is stored in a file named app.rb
and that you are using the default URL for a local Sinatra application, http://localhost:4567
.
-
In your terminal, from the directory where
app.rb
is stored, runruby app.rb
. A local Sinatra server should start. -
In your browser, navigate to
http://localhost:4567
. You should see a link with the text "Login with GitHub". -
Click on the "Login with GitHub" link.
If you have not authorized the app, clicking on the link should take you to
https://github.com/login/oauth/authorize?client_id=CLIENT_ID
, whereCLIENT_ID
is the client ID of your app. This is a GitHub page that prompts users to authorize your app. If you click the button to authorize your app, you will go to the callback URL for your app.If you previously authorized your app and the authorization has not been revoked, you will skip the authorization prompt and go directly to the callback URL instead. You can revoke your previous authorization if you want to see the authorization prompt. For more information, see "Reviewing and revoking authorization of GitHub Apps."
-
The callback URL page, reached by clicking the "Login with GitHub" link and then authorizing the app if prompted to do so, should display the text similar to "Successfully authorized! Welcome, Mona Lisa (octocat)."
-
In your terminal where Sinatra is running, stop the server by entering Ctrl+C.
Next steps
Securely store your client secret
You should never publicize your app's client secret. This tutorial stored the client secret in a gitignored .env
file and accessed the value with ENV.fetch
. When you deploy your app, you should choose a secure way to store the client secret and update your code to get the value accordingly.
For example, you can store the secret in an environment variable on the server where your application is deployed. You can also use a secret management service like Azure Key Vault.
Update the callback URL for deployment
This tutorial used a callback URL starting with http://localhost:4567
. However, http://localhost:4567
is only available locally to your computer when you start the Sinatra server. Before you deploy your app, you should update the callback URL to use the callback URL that you use in production. For more information about updating the callback URL for your app, see "Modifying a GitHub App registration" and "About the user authorization callback URL."
Handle multiple callback URLs
This tutorial used a single callback URL, but your app can have up to 10 callback URLs. If you want to use multiple callback URLs:
- Add the additional callback URLs to your app. For more information about adding callback URLs, see "Modifying a GitHub App registration."
- When you link to
https://github.com/login/oauth/authorize
, use theredirect_uri
query parameter to redirect users to the desired callback URL. For more information, see "Generating a user access token for a GitHub App." - In your app code, handle each callback URL, similar to the code block starting in
get "CALLBACK_URL" do
.
Specify additional parameters
When you link to https://github.com/login/oauth/authorize
, you can pass additional query parameters. For more information, see "Generating a user access token for a GitHub App."
Unlike a traditional OAuth token, the user access token does not use scopes so you cannot specify scopes via the scope
parameter. Instead, it uses fine-grained permissions. A user access token only has permissions that both the user and the app have.
Adjust the code to meet your app's needs
This tutorial demonstrated how to display information about the authenticated user, but you can adjust this code to take other actions. Remember to update your app's permissions if your app needs additional permissions for the API requests that you want to make. For more information, see "Choosing permissions for a GitHub App."
This tutorial stored all of the code into a single file, but you may want to move functions and components into separate files.
Securely store tokens
This tutorial generates a user access token. Unless you opted out of expiration for user access tokens, the user access token will expire after eight hours. You will also receive a refresh token that can regenerate a user access token. For more information, see "Refreshing user access tokens."
If you plan on interacting further with GitHub's APIs, you should store the token for future use. If you choose to store the user access token or refresh token, you must store it securely. You should never publicize the token.
For more information, see "Best practices for creating a GitHub App."
Follow best practices
You should aim to follow best practices with your GitHub App. For more information, see "Best practices for creating a GitHub App."