Why don't Monolog logs get into "Docker logs"?

Question

PHP

Hello. I am setting up work with logs, I want to hook up a certain aggregator and collect all the logs with it. The aggregator receives logs that are visible in docker logs (that is, from stdout and stderr streams).
In my application, I'm trying to write a log to stdout and see it with the docker logs command:

$logger = new \Monolog\Logger('MyTestName');
$handler = new StreamHandler('php://stdout', Logger::DEBUG);
$logger->pushHandler($handler);
$logger->error('My test error message');

However, only nginx is shown in the output of docker logs, no more logs are included.

Tell me what I missed?

Answer 1

You run multiple applications inside the same container and naively assume that they all have the same first two file descriptors.