Lua

Get Google API Access Token using JSON Private Key using NIST Time Server Date/Time

Demonstrates how to get a Google API access token using a JSON service account private key, using the NIST time server date/time rather than the local system date/time. Lua

local chilkat = require("chilkat")

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

-- First, let's get the current date/time from time-c.nist.gov
local socket = chilkat.Socket.new()

-- Connect to an NIST time server and read the current date/time
local maxWaitMs = 8000
local useTls = false
local success = socket:connect("time-c.nist.gov", 37, useTls, maxWaitMs)
if not success then
    print(socket.last_error_text)
    return
end

-- The time server will send a big-endian 32-bit integer representing
-- the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
-- The ReceiveInt32 method will receive a 4-byte integer, but returns
-- true or false to indicate success.  If successful, the integer
-- is obtained via the ReceivedInt property.
local bigEndian = true
success = socket:receive_int32(bigEndian)
if not success then
    print(socket.last_error_text)
    return
end

local dt = chilkat.DateTime.new()
dt:set_from_ntp_time(socket.received_int)

-- Show the current local date/time
local bLocalTime = true
print("Current local date/time: " .. dt:get_as_rfc822(bLocalTime))

maxWaitMs = 10
socket:close(maxWaitMs)

-- ------------------------------------------------------------------------
-- OK, we have the current date/time.  We'll use it to set the IAT property
-- in the code below.

-- First load the JSON key into a string.
local fac = chilkat.FileAccess.new()
local jsonKey = fac:read_entire_text_file("qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json", "utf-8")
if not fac.last_method_success then
    print(fac.last_error_text)
    return
end

-- A JSON private key should look 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"
--     }

local gAuth = chilkat.AuthGoogle.new()
gAuth.json_key = jsonKey

-- Choose a scope.
gAuth.scope = "https://www.googleapis.com/auth/cloud-platform"

-- Request an access token that is valid for this many seconds.
gAuth.expire_num_seconds = 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.sub_email_address = ""

-- ------------------------------------------------------------------------
-- Set the IAT using the date/time from the NIST time server.
local unixTime = dt:get_as_unix_time(false)
print("unixTime = " .. unixTime)
gAuth.iat = unixTime

-- 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.
local tlsSock = chilkat.Socket.new()
success = tlsSock:connect("www.googleapis.com", 443, true, 5000)
if not success then
    print(tlsSock.last_error_text)
    return
end

-- Send the request to obtain the access token.
success = gAuth:obtain_access_token(tlsSock)
if not success then
    print(gAuth.last_error_text)
    return
end

-- Examine the access token:
print("Access Token: " .. gAuth.access_token)