"Do not run Composer as root/super user! See https://getcomposer.org/root for details."
By default composer commands will not execute if its running as root user.
In docker automation setups all the commands running as root user and as a result composer failed execution.
We can solve this problem by adding one optoin to the docker command.
For example to run composer install,
#docker exec CONTAINERID COMPOSER_ALLOW_SUPERUSER=1 composer install
Here CONTAINERID should be replaced by the id of the docker container.
In this way we can run any composer commands without any issues.