(Lianja) 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...

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// 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.
loFac = createobject("CkFileAccess")
lcJsonKey = loFac.ReadEntireTextFile("qa_data/firebase/firebase-chilkat-firebase-adminsdk-n28n4-1b664ee163.json","utf-8")
if (loFac.LastMethodSuccess <> .T.) then
    ? loFac.LastErrorText
    release loFac
    return
endif

// 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"
// } 
// 

loGAuth = createobject("CkAuthGoogle")
loGAuth.JsonKey = lcJsonKey

// 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"

loGAuth.Scope = "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.
loGAuth.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.)
loGAuth.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.
loTlsSock = createobject("CkSocket")
llSuccess = loTlsSock.Connect("www.googleapis.com",443,.T.,5000)
if (llSuccess <> .T.) then
    ? loTlsSock.LastErrorText
    release loFac
    release loGAuth
    release loTlsSock
    return
endif

// Send the request to obtain the access token.
llSuccess = loGAuth.ObtainAccessToken(loTlsSock)
if (llSuccess <> .T.) then
    ? loGAuth.LastErrorText
    release loFac
    release loGAuth
    release loTlsSock
    return
endif

// Examine the access token:
? "Firebase Access Token: " + loGAuth.AccessToken

// Save the token to a file (or wherever desired).  This token is valid for 1 hour.
loFac.WriteEntireTextFile("qa_data/tokens/firebaseToken.txt",loGAuth.AccessToken,"utf-8",.F.)


release loFac
release loGAuth
release loTlsSock