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Get Firebase Access Token from JSON Service Account Private Key

See more Firebase Examples

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...

Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // 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.
    const fac = try chilkat.FileAccess.init();
    defer fac.deinit();
    const json_key = fac.readEntireTextFile(alloc, "qa_data/firebase/firebase-chilkat-firebase-adminsdk-n28n4-1b664ee163.json", "utf-8") catch {
        std.debug.print("{s}\n", .{try fac.getLastErrorText(alloc)});
        return;
    };

    // 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"
    // }
    //

    const g_auth = try chilkat.AuthGoogle.init();
    defer g_auth.deinit();
    g_auth.setJsonKey(json_key);

    // 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"

    g_auth.setScope("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.
    g_auth.setExpireNumSeconds(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.)
    g_auth.setSubEmailAddress("");

    // 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.
    const tls_sock = try chilkat.Socket.init();
    defer tls_sock.deinit();
    tls_sock.connect("www.googleapis.com", 443, true, 5000) catch {
        std.debug.print("{s}\n", .{try tls_sock.getLastErrorText(alloc)});
        return;
    };

    // Send the request to obtain the access token.
    g_auth.obtainAccessToken(tls_sock) catch {
        std.debug.print("{s}\n", .{try g_auth.getLastErrorText(alloc)});
        return;
    };

    // Examine the access token:
    std.debug.print("Firebase Access Token: {s}\n", .{try g_auth.getAccessToken(alloc)});

    // Save the token to a file (or wherever desired).  This token is valid for 1 hour.
    fac.writeEntireTextFile("qa_data/tokens/firebaseToken.txt", try g_auth.getAccessToken(alloc), "utf-8", false) catch {};
}