Pascal (Lazarus/Delphi)

Get Google Cloud Storage Access Token using Service Account JSON Private Key

See more Google Cloud Storage Examples

Demonstrates how to get a Google Cloud Storage 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.

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.FileAccess,
  Chilkat.AuthGoogle,
  Chilkat.StringBuilder,
  Chilkat.Socket;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  fac: TFileAccess;
  jsonKey: string;
  gAuth: TAuthGoogle;
  tlsSock: TSocket;
  sbToken: TStringBuilder;

begin
  success := False;

  //  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 := TFileAccess.Create;
  jsonKey := fac.ReadEntireTextFile('qa_data/googleApi/ChilkatCloud-13a07a2e8b3f.json','utf-8');
  if (fac.LastMethodSuccess <> True) then
    begin
      WriteLn(fac.LastErrorText);
      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 := TAuthGoogle.Create;
  gAuth.JsonKey := 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.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.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 := TSocket.Create;
  success := tlsSock.Connect('www.googleapis.com',443,True,5000);
  if (success <> True) then
    begin
      WriteLn(tlsSock.LastErrorText);
      Exit;
    end;

  //  Send the request to obtain the access token.
  success := gAuth.ObtainAccessToken(tlsSock);
  if (success <> True) then
    begin
      WriteLn(gAuth.LastErrorText);
      Exit;
    end;

  //  Examine the access token:
  WriteLn('Access Token: ' + gAuth.AccessToken);

  //  We're going to save this access token to a file to be used
  //  by other examples.
  sbToken := TStringBuilder.Create;
  sbToken.Append(gAuth.AccessToken);
  sbToken.WriteFile('qa_data/tokens/googleCloudStorageAccessToken.txt','utf-8',False);


  fac.Free;
  gAuth.Free;
  tlsSock.Free;
  sbToken.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.