Google compute engine instance start/status/stop using api - php

Question

I need to start the google cloud instance and stop if my process is over.
So i tried api calls from https://cloud.google.com/compute/docs/reference/rest/v1/instances/get
Created API Key and oAuth client Id for the same and tried in postman application to test.
Used API Key in header Authorization : Bearer <api_key> and also in URL as key=<api_key>
But both methods are giving error 401 login required.
Then i found API Explorer
https://developers.google.com/apis-explorer/
There also i got same error.
What is the mistake I'm doing.
I need to implement instance start and stop through PHP code as it is background process.
PHP curl response
{
"error": {
"errors": [
{
"domain": "global",
"reason": "authError",
"message": "Invalid Credentials",
"locationType": "header",
"location": "Authorization"
}
],
"code": 401,
"message": "Invalid Credentials"
}
}

Answer 1

I think the easiest way to actually do this using env variable, as the google api php client library has a neat method.
require_once __DIR__ . '/vendor/autoload.php';
putenv('GOOGLE_APPLICATION_CREDENTIALS=/path/to/service-account.json');
$client = new Google_Client();
$client->setApplicationName('RandomNameYouNeedToInsert/0.1');
$client->addScope(array('https://www.googleapis.com/auth/compute'));
$client->useApplicationDefaultCredentials();
$service = new Google_Service_Compute($client);
// TODO: Update placeholder values.
project = 'my-project';
$zone = 'my-zone';
$instance = 'my-instance';
$response = $service->instances->start($project, $zone, $instance);
// TODO: Check if the response satisfies your request.