Logging from PHP to Docker logs (stdout)

If you run your PHP application inside a docker container, you could write (debug) output to the docker log. This is useful if you want to see the output of your application in the docker logs.


$out = fopen('php://stdout', 'w'); //output handler
fputs($out, "Output goes here...."); //writing output operation
fclose($out); //closing handler


function _log($msg) {
    $msg = "myApp - " . date("c") . ": " . $msg."\n";
    $out = fopen('php://stdout', 'w');
    fputs($out, $msg);

Grafana/Telegraf show 0 bytes memory usage for docker containers

Today i searched for a problem with a docker container. Since there was a problem with the memory usage of the container, I wanted to check it in my Grafana. But unfortunately, the Telegraf plugin showed 0 bytes for each container since months. I founded the solution the the Telegraf GitHub issues. You need to enable memory control groups on Raspberry Pi. To do that, add the following to your /boot/cmdline.txt to enable this metic:

cgroup_enable=memory cgroup_memory=1

And after reboot, it works: