(Ruby) Get GMail SMTP OAuth2 Access Token for Desktop App

See more OAuth2 Examples

Note: This example requires Chilkat v10.1.2 or greater.

Chilkat Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

# To further clarify, see OAuth 2.0 Authorization Flow

oauth2 = Chilkat::CkOAuth2.new()

# For Google OAuth2, set the listen port equal to the port used
# in the Authorized Redirect URL for the Client ID.
# For example, in this case the Authorized Redirect URL would be http://localhost:55568/
# Your app should choose a port not likely not used by any other application.
oauth2.put_ListenPort(55568)

oauth2.put_AuthorizationEndpoint("https://accounts.google.com/o/oauth2/v2/auth")
oauth2.put_TokenEndpoint("https://www.googleapis.com/oauth2/v4/token")

# Replace these with actual values.
oauth2.put_ClientId("GOOGLE-CLIENT-ID")
oauth2.put_ClientSecret("GOOGLE-CLIENT-SECRET")

# To use Gmail's OAuth2 for sending emails via the SMTP protocol, you need to request the https://mail.google.com/ scope. 
# See About GMail SMTP OAuth2 Scopes
oauth2.put_Scope("https://mail.google.com/")

# Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
url = oauth2.startAuth()
if (oauth2.get_LastMethodSuccess() != true)
    print oauth2.lastErrorText() + "\n";
    exit
end

# Launch the default browser on the system and navigate to the url.
# The LaunchBrowser method was added in Chilkat v10.1.2.
success = oauth2.LaunchBrowser(url)
if (success == false)
    print oauth2.lastErrorText() + "\n";
    exit
end

# Wait for the user to approve or deny authorization in the browser.
numMsWaited = 0
while (numMsWaited < 90000) and (oauth2.get_AuthFlowState() < 3)
    oauth2.SleepMs(100)
    numMsWaited = numMsWaited + 100
end

# If the browser does not respond within the specified time, AuthFlowState will be:
# 
# 1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
# 2: Waiting for Final Response – The thread is awaiting the final access token response.
# In either case, cancel the background task initiated by StartAuth.

if (oauth2.get_AuthFlowState() < 3)
    oauth2.Cancel()
    print "No response from the browser!" + "\n";
    exit
end

# Check AuthFlowState to determine if authorization was granted, denied, or failed:
# 
# 3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
# 4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
# 5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

if (oauth2.get_AuthFlowState() == 5)
    print "OAuth2 failed to complete." + "\n";
    print oauth2.failureInfo() + "\n";
    exit
end

if (oauth2.get_AuthFlowState() == 4)
    print "OAuth2 authorization was denied." + "\n";
    print oauth2.accessTokenResponse() + "\n";
    exit
end

if (oauth2.get_AuthFlowState() != 3)
    print "Unexpected AuthFlowState:" + oauth2.get_AuthFlowState().to_s() + "\n";
    exit
end

# Save the full JSON access token response to a file.
sbJson = Chilkat::CkStringBuilder.new()
sbJson.Append(oauth2.accessTokenResponse())
sbJson.WriteFile("qa_data/tokens/_gmailSmtp.json","utf-8",false)

# The saved JSON response looks like this:

# 	{
# 	 "access_token": "ya39.Ci-XA_C5bGgRDC3UaD-h0_NeL-DVIQnI2gHtBBBHkZzrwlARkwX6R3O0PCDEzRlfaQ",
# 	 "token_type": "Bearer",
# 	 "expires_in": 3600,
# 	 "refresh_token": "1/r_2c_7jddspcdfesrrfKqfXtqo08D6Q-gUU0DsdfVMsx0c"
# 	}
# 
print "OAuth2 authorization granted!" + "\n";
print "Access Token = " + oauth2.accessToken() + "\n";