Google Cloud Functions app doesn't write custom logs - google-cloud-functions

Question

Recently I've set up an application in Google Cloud Functions. It's a pet project, I just want to get a grasp on how things work on this platform. I'm trying to write custom application logs. I run the exact same code as given in an example here:
function entryPoint(ServerRequestInterface $request): string
{
$log = fopen('php://stderr', 'wb');
fwrite($log, "Log entry from fwrite().\n");
fwrite($log, json_encode([
'message' => 'Structured log with error severity',
'severity' => 'error'
]) . PHP_EOL);
fwrite(
log,
json_encode([
'logName' => 'projects/lyrical-bolt-XXX/logs/cloudfunctions.googleapis.com%2Fcloud-functions',
'resource' => [
'type' => 'cloud_function',
'labels' => [
'project_id' => 'lyrical-bolt-XXX',
'function_name' => 'index',
'region' => 'europe-central2'
]
],
'textPayload' => 'Hello, Vasya! How are you??'
]) . PHP_EOL
);
return '';
}
Then I open Logs Explorer but my logs are just not there:
Am I missing anything? Maybe there are any permissions that I should grant to anything? If so, where exactly can I do it?

Answer 1

Your code works for me. I replaced your 3rd log with a debug:
gcloud functions logs read test \
--region=${REGION} \
--project=${PROJECT}
Yields:
LEVEL NAME EXECUTION_ID TIME_UTC LOG
D test ppg5pq2nle4b 2021-07-07 17:43:46.364 Function execution took 9 ms, finished with status code: 200
test ppg5pq2nle4b 2021-07-07 17:43:46.363 [07-Jul-2021 17:43:46] WARNING: [pool app] child 19 said into stderr: "{"message":"Structured log with debug severity","severity":"debug"}"
test ppg5pq2nle4b 2021-07-07 17:43:46.363 [07-Jul-2021 17:43:46] WARNING: [pool app] child 19 said into stderr: "{"message":"Structured log with error severity","severity":"error"}"
test ppg5pq2nle4b 2021-07-07 17:43:46.363 [07-Jul-2021 17:43:46] WARNING: [pool app] child 19 said into stderr: "Log entry from fwrite()."
D test ppg5pq2nle4b 2021-07-07 17:43:46.355 Function execution started
D test ppg579syhkvj 2021-07-07 17:43:45.126 Function execution took 3 ms, finished with status code: 200
test ppg579syhkvj 2021-07-07 17:43:45.126 [07-Jul-2021 17:43:45] WARNING: [pool app] child 17 said into stderr: "{"message":"Structured log with error severity","severity":"error"}"
test ppg579syhkvj 2021-07-07 17:43:45.126 [07-Jul-2021 17:43:45] WARNING: [pool app] child 17 said into stderr: "Log entry from fwrite()."
test ppg579syhkvj 2021-07-07 17:43:45.126 [07-Jul-2021 17:43:45] WARNING: [pool app] child 17 said into stderr: "{"message":"Structured log with debug severity","severity":"debug"}"
D test ppg579syhkvj 2021-07-07 17:43:45.123 Function execution started
D test ppg56xpfu1ym 2021-07-07 17:43:43.859 Function execution took 118 ms, finished with status code: 200
test ppg56xpfu1ym 2021-07-07 17:43:43.856 [07-Jul-2021 17:43:43] WARNING: [pool app] child 17 said into stderr: "{"message":"Structured log with debug severity","severity":"debug"}"
test ppg56xpfu1ym 2021-07-07 17:43:43.856 [07-Jul-2021 17:43:43] WARNING: [pool app] child 17 said into stderr: "{"message":"Structured log with error severity","severity":"error"}"
test ppg56xpfu1ym 2021-07-07 17:43:43.856 [07-Jul-2021 17:43:43] WARNING: [pool app] child 17 said into stderr: "Log entry from fwrite()."
D test ppg56xpfu1ym 2021-07-07 17:43:43.742 Function execution started
I test 2021-07-07 17:43:13.164 [pid1-nginx] Starting nginx (pid 18): /usr/sbin/nginx -c /tmp/nginxconf-466886520/nginx.conf
I test 2021-07-07 17:43:13.158 [pid1-nginx] Successfully connected to /tmp/google-config/app.sock after 251.013037ms
test 2021-07-07 17:43:12.951 [serve] Running /bin/sh -c exec php-fpm -R --nodaemonize --fpm-config /tmp/serve-php-051025325/php-fpm.conf
test 2021-07-07 17:43:12.950 [serve] workersFromArgs: memoryMB:256 flagAppWorkers:0 workers:2
test 2021-07-07 17:43:12.945 [serve] Could not parse memory limit; defaulting to 256MiB.
NOTE You do not include the Google Logging logName, resource etc. properties. This is metadata that wraps what you write to stdout and stderr
NOTE You have a typo on line #17 fwrite(log, should be fwrite($log,