(Ruby) Get Google Cloud SQL Access Token using Service Account JSON Private Key

Demonstrates how to get a Google Cloud SQL access token using a JSON service account private key. Obtaining an access token for a service account requires no user interaction (it does not require a browser, nor callback URI's, etc.).

When an access token expires, an application can be (and should be) designed to automatically fetch a new access token.

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

require 'chilkat'

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

# First load the JSON key into a string.
fac = Chilkat::CkFileAccess.new()
jsonKey = fac.readEntireTextFile("qa_data/googleApi/ChilkatCloud-13a07a2e8b3f.json","utf-8")
if (fac.get_LastMethodSuccess() != true)
    print fac.lastErrorText() + "\n";
    exit
end

# A JSON private key should look something like this:

# 	{
# 	  "type": "service_account",
# 	  "project_id": "chilkattest-1350",
# 	  "private_key_id": "fa2e36ee26986eab628b59868af8bec1d1c64c38",
# 	  "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIjFa...28N64N2n1E4FYzBZjSdy\n-----END PRIVATE KEY-----\n",
# 	  "client_email": "598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a@developer.gserviceaccount.com",
# 	  "client_id": "598922945226-00rb0ppfg0snd9jo7bhvd4v17jtj2d3a.apps.googleusercontent.com",
# 	  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
# 	  "token_uri": "https://accounts.google.com/o/oauth2/token",
# 	  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
# 	  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a%40developer.gserviceaccount.com"
# 	}

gAuth = Chilkat::CkAuthGoogle.new()
gAuth.put_JsonKey(jsonKey)

# Choose a scope.
# Here's the OAuth 2.0 scope information for the Cloud SQL Admin API:
# https://www.googleapis.com/auth/sqlservice.admin 	(Read/write access to Cloud SQL.)
# https://www.googleapis.com/auth/cloud-platform 	(Instances.import and Instances.export need this additional scope.)
gAuth.put_Scope("https://www.googleapis.com/auth/sqlservice.admin")

# Request an access token that is valid for this many seconds.
gAuth.put_ExpireNumSeconds(3600)

# If the application is requesting delegated access:
# The email address of the user for which the application is requesting delegated access,
# then set the email address here. (Otherwise leave it empty.)
gAuth.put_SubEmailAddress("")

# Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
# The Chilkat socket object is used so that the connection can be established
# through proxies or an SSH tunnel if desired.
tlsSock = Chilkat::CkSocket.new()
success = tlsSock.Connect("www.googleapis.com",443,true,5000)
if (success != true)
    print tlsSock.lastErrorText() + "\n";
    exit
end

# Send the request to obtain the access token.
success = gAuth.ObtainAccessToken(tlsSock)
if (success != true)
    print gAuth.lastErrorText() + "\n";
    exit
end

# Examine the access token:
print "Access Token: " + gAuth.accessToken() + "\n";

# Access token looks like this:  ya29.c.Ko4Bwwe3nG5rUvoBmJwadi ... Br4Ogz0B6qLAjg

# We're going to save this access token to a file to be used
# by other examples.
sbToken = Chilkat::CkStringBuilder.new()
sbToken.Append(gAuth.accessToken())
sbToken.WriteFile("qa_data/tokens/google_cloud_sql_access_token.txt","utf-8",false)