How to generate PHP web application output to docker stdout?

[Commifreak]

Hi,

is it possible to send some output to the docker containers stdout/stderr to be visible inside docker log for this container? Am I abel to write to /proc/1/fd/2 or something similar?

[shinsenter]

@Commifreak Hi.

I'm not sure which tag of the Docker images you're using. By default, logs are sent directly to docker logs, so I don't think any additional configuration is needed.

By the way, are you referring to logs from a specific program or task?

[shinsenter]

I might have misunderstood your point earlier. Additionally, if you want to output logs directly to the Docker container's standard output, you can simply write them to /dev/stdout or /dev/stderr. For example:

echo "Hello" >>/dev/stdout

You can view using docker logs.

[shinsenter]

If you're running a command manually in an interactive terminal and want to output directly to Docker's standard output, you'll need root permission to write to /proc/1/fd/2.
For example:

echo "Hello" >> /proc/1/fd/2

This sends the output to the main process’s stderr inside the container, which is captured by Docker logs.

[Commifreak]

I mean within PHP. I tried file_put_contents to /dev/stdout, but PHP keeps saying its not accesible. Anyother way to let a php script output something on containers stdout? I want some output to be visible directly, when I access the docker log for this container.

[shinsenter]

I don't think this is an issue specific to the Docker images I provide. You can check Google for related issues, or for more solutions.

https://stackoverflow.com/questions/56583510/why-cant-i-write-to-dev-stdout-but-php-stdout-works

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You may try using error_log to send the log to PHP's system logger.

error_log($msg, 0);

[Commifreak]

Yes, error_log is working! It shows the PHP notices now in docker logs! Thanks!