Run composer scripts as www-data user in docker container - docker

Question

I am using composer to run some system workers on the docker container, which is normally started with the www-data user on remote servers.
When I run them on the docker container they are started by the root user which is not correct, because the www-data user can not stop them from the browser app.
composer.json
...
"require": {
...
},
"scripts": {
"worker:start": [
"php path/to/the/script"
],
},
...
Start the script on the docker container
composer worker:start
And top results
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1 root 20 0 267152 36396 29584 S 0.0 0.2 0:00.12 php-fpm
91 root 20 0 19132 4216 2208 S 0.0 0.0 0:00.04 sendmail-mta
103 www-data 20 0 267152 8952 2136 S 0.0 0.1 0:00.00 php-fpm
104 www-data 20 0 267152 8952 2136 S 0.0 0.1 0:00.00 php-fpm
154 root 20 0 2528 580 488 S 0.0 0.0 0:00.00 timeout
156 root 20 0 124460 56344 27900 S 0.0 0.4 0:00.18 php
157 root 20 0 2528 576 484 S 0.0 0.0 0:00.00 timeout
159 root 20 0 124460 55484 28224 S 0.0 0.3 0:00.19 php
160 root 20 0 2528 584 488 S 0.0 0.0 0:00.00 timeout
161 root 20 0 129012 61356 28020 S 0.0 0.4 0:00.27 php
162 root 20 0 4100 3428 2920 S 0.0 0.0 0:00.02 bash
168 root 20 0 7016 3360 2820 T 0.0 0.0 0:00.02 top
189 root 20 0 2528 576 484 S 0.0 0.0 0:00.00 timeout
191 root 20 0 124460 54948 27436 S 0.0 0.3 0:00.17 php
192 root 20 0 2528 576 484 S 0.0 0.0 0:00.00 timeout
194 root 20 0 122280 54548 28080 S 0.0 0.3 0:00.15 php
195 root 20 0 2528 640 548 S 0.0 0.0 0:00.00 timeout
196 root 20 0 128968 60336 27972 S 0.0 0.4 0:00.23 php
197 root 20 0 7016 3352 2812 R 0.0 0.0 0:00.00 top
As you see, only php-fpm proccess is run with www-data user.
How to configure docker container to run all PHP processes as www-data user instead root?

Answer 1

The reason FPM is running with that user is because it's written in the FPM config file. So it doesn't run as the root user, but as the user in the config file.
For example, somewhere in one of your FPM config files are settings simular to the below:
[www]
user = www-data
group = www-data
Composer doesn't seem to do this. At least not by default or with its current configuration.
I suggest generally switching the user in the docker container, for security purposes. Put this at the end of your Dockerfile.
USER www-data
This is good security practice and should also fix your problem.