(SQL Server) OAuth2 for a GMail using a JSON Service Account Key

This example shows how to obtain an OAuth2 access token for Gmail using a Google Service Account and a JSON private key. Once acquired, the access token can be used to send emails. Remember, upon token expiration, this process needs to be repeated to obtain a new token. Note: This procedure is specific to OAuth2 with Google Service Account keys.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    -- This example requires the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    -- --------------------------------------------------------------------------------
    -- For a step-by-step guide for setting up your Google Workspace service account,
    -- see Setup Google Workspace Account for Sending SMTP GMail from a Service Account
    -- --------------------------------------------------------------------------------

    -- First load the JSON key into a string.
    DECLARE @fac int
    EXEC @hr = sp_OACreate 'Chilkat.FileAccess', @fac OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @jsonKey nvarchar(4000)
    EXEC sp_OAMethod @fac, 'ReadEntireTextFile', @jsonKey OUT, 'qa_data/googleApi/chilkat25-b4214220e565.json', 'utf-8'
    EXEC sp_OAGetProperty @fac, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 <> 1
      BEGIN
        EXEC sp_OAGetProperty @fac, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @fac
        RETURN
      END

    -- A Google service account JSON private key looks like this:

    -- {
    --   "type": "service_account",
    --   "project_id": "chilkat25",
    --   "private_key_id": "b4214220f565881e19eeb97c2699bf5a0d1e3e0b",
    --   "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvQ...NXcM=\n-----END PRIVATE KEY-----\n",
    --   "client_email": "chilkatsvc@chilkat25.iam.gserviceaccount.com",
    --   "client_id": "109122032928932715958",
    --   "auth_uri": "https://accounts.google.com/o/oauth2/auth",
    --   "token_uri": "https://oauth2.googleapis.com/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/chilkatsvc%40chilkat25.iam.gserviceaccount.com",
    --   "universe_domain": "googleapis.com"
    -- }

    DECLARE @gAuth int
    EXEC @hr = sp_OACreate 'Chilkat.AuthGoogle', @gAuth OUT

    EXEC sp_OASetProperty @gAuth, 'JsonKey', @jsonKey

    -- Specify a scope.
    EXEC sp_OASetProperty @gAuth, 'Scope', 'https://mail.google.com/'

    -- Request an access token that is valid for this many seconds.
    EXEC sp_OASetProperty @gAuth, 'ExpireNumSeconds', 3600

    -- When using a Google Workspace account with Gmail APIs, a service account can impersonate a user 
    -- via a process called domain-wide delegation � and the "sub" claim in the JWT is what enables this.
    -- Domain-wide delegation allows a Google Workspace administrator to authorize a service account to 
    -- act on behalf of any user in the domain, without user interaction.

    -- This is required for server-to-server access to user data � such as reading/sending Gmail from a background service.
    -- This is your company email address.
    EXEC sp_OASetProperty @gAuth, 'SubEmailAddress', 'info@chilkat.xyz'

    -- Connect to www.googleapis.com using TLS
    DECLARE @tlsSock int
    EXEC @hr = sp_OACreate 'Chilkat.Socket', @tlsSock OUT

    DECLARE @success int
    EXEC sp_OAMethod @tlsSock, 'Connect', @success OUT, 'www.googleapis.com', 443, 1, 5000
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @tlsSock, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @fac
        EXEC @hr = sp_OADestroy @gAuth
        EXEC @hr = sp_OADestroy @tlsSock
        RETURN
      END

    -- Send the request to obtain the access token.
    EXEC sp_OAMethod @gAuth, 'ObtainAccessToken', @success OUT, @tlsSock
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @gAuth, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @fac
        EXEC @hr = sp_OADestroy @gAuth
        EXEC @hr = sp_OADestroy @tlsSock
        RETURN
      END

    -- Examine the access token:
    DECLARE @accessToken nvarchar(4000)
    EXEC sp_OAGetProperty @gAuth, 'AccessToken', @accessToken OUT

    PRINT 'Access Token: ' + @accessToken

    -- Sample output:
    -- ya29.a0AW4XtxjGTD67Z8 .... IRw0218

    -- The access token allows us to send unlimited emails while it's valid. Once it expires, we must obtain and use a new one.

    -- -----------------------------------------------------------------------
    DECLARE @mailman int
    EXEC @hr = sp_OACreate 'Chilkat.MailMan', @mailman OUT

    -- Set the properties for the GMail SMTP server:
    EXEC sp_OASetProperty @mailman, 'SmtpHost', 'smtp.gmail.com'
    EXEC sp_OASetProperty @mailman, 'SmtpPort', 587
    EXEC sp_OASetProperty @mailman, 'StartTLS', 1

    EXEC sp_OASetProperty @mailman, 'SmtpUsername', 'info@chilkat.xyz'
    EXEC sp_OASetProperty @mailman, 'OAuth2AccessToken', @accessToken

    -- Create a new email object
    DECLARE @email int
    EXEC @hr = sp_OACreate 'Chilkat.Email', @email OUT

    EXEC sp_OASetProperty @email, 'Subject', 'This is a test'
    EXEC sp_OASetProperty @email, 'Body', 'This is a test'
    EXEC sp_OASetProperty @email, 'From', 'Chilkat Test <info@chilkat.xyz>'
    EXEC sp_OAMethod @email, 'AddTo', @success OUT, 'Chilkat Software', 'info@chilkatsoft.com'
    -- To add more recipients, call AddTo, AddCC, or AddBcc once per recipient.

    EXEC sp_OAMethod @mailman, 'SendEmail', @success OUT, @email
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @mailman, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @fac
        EXEC @hr = sp_OADestroy @gAuth
        EXEC @hr = sp_OADestroy @tlsSock
        EXEC @hr = sp_OADestroy @mailman
        EXEC @hr = sp_OADestroy @email
        RETURN
      END

    EXEC sp_OAMethod @mailman, 'CloseSmtpConnection', @success OUT
    IF @success <> 1
      BEGIN

        PRINT 'Connection to SMTP server not closed cleanly.'
      END


    PRINT 'Successfully sent email using Gmail with a service account key.'

    EXEC @hr = sp_OADestroy @fac
    EXEC @hr = sp_OADestroy @gAuth
    EXEC @hr = sp_OADestroy @tlsSock
    EXEC @hr = sp_OADestroy @mailman
    EXEC @hr = sp_OADestroy @email


END
GO