(Delphi DLL) Get Firebase Access Token from JSON Service Account Private Key

Demonstrates how to get a Firebase access token using a JSON service account private key. Your Firebase service account can be used to authenticate multiple Firebase features, such as Database, Storage and Auth, programmatically.

A Firebase JSON service account private key can be created in the Firebase settings/admin portion of the console.firebase.google.com site as shown here:

Scroll down to see the example code...

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, FileAccess, AuthGoogle, Socket;

...

procedure TForm1.Button1Click(Sender: TObject);
var
fac: HCkFileAccess;
jsonKey: PWideChar;
gAuth: HCkAuthGoogle;
tlsSock: HCkSocket;
success: Boolean;

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

// First load the Firebase JSON private key into a string.
fac := CkFileAccess_Create();
jsonKey := CkFileAccess__readEntireTextFile(fac,'qa_data/firebase/firebase-chilkat-firebase-adminsdk-n28n4-1b664ee163.json','utf-8');
if (CkFileAccess_getLastMethodSuccess(fac) <> True) then
  begin
    Memo1.Lines.Add(CkFileAccess__lastErrorText(fac));
    Exit;
  end;

// A Firebase JSON private key should look something like this:

// { 
//   "type": "service_account",
//   "project_id": "firebase-chilkat",
//   "private_key_id": "1c664ee164907413c91ddefcf5b765ecba8779e2",
//   "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvQIBA ... Ya2UZii/lXn73/ZOK8=\n-----END PRIVATE KEY-----\n",
//   "client_email": "firebase-adminsdk-n28n4@firebase-chilkat.iam.gserviceaccount.com",
//   "client_id": "134846322329335418431",
//   "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/firebase-adminsdk-n28n4%40firebase-chilkat.iam.gserviceaccount.com"
// } 
// 

gAuth := CkAuthGoogle_Create();
CkAuthGoogle_putJsonKey(gAuth,jsonKey);

// Choose a scope.
// The scope could be "https://www.googleapis.com/auth/firebase.database"
// or a space-delimited list of scopes:
// "https://www.googleapis.com/auth/firebase.database https://www.googleapis.com/auth/userinfo.email"

CkAuthGoogle_putScope(gAuth,'https://www.googleapis.com/auth/firebase.database https://www.googleapis.com/auth/userinfo.email');

// Request an access token that is valid for this many seconds.
CkAuthGoogle_putExpireNumSeconds(gAuth,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.)
CkAuthGoogle_putSubEmailAddress(gAuth,'');

// 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 := CkSocket_Create();
success := CkSocket_Connect(tlsSock,'www.googleapis.com',443,True,5000);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(tlsSock));
    Exit;
  end;

// Send the request to obtain the access token.
success := CkAuthGoogle_ObtainAccessToken(gAuth,tlsSock);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkAuthGoogle__lastErrorText(gAuth));
    Exit;
  end;

// Examine the access token:
Memo1.Lines.Add('Firebase Access Token: ' + CkAuthGoogle__accessToken(gAuth));

// Save the token to a file (or wherever desired).  This token is valid for 1 hour.
CkFileAccess_WriteEntireTextFile(fac,'qa_data/tokens/firebaseToken.txt',CkAuthGoogle__accessToken(gAuth),'utf-8',False);

CkFileAccess_Dispose(fac);
CkAuthGoogle_Dispose(gAuth);
CkSocket_Dispose(tlsSock);

end;