While COPY and ADD are essentially interchangeable here, it is still
considered good practice to use COPY whenever possible. From the docker
docks on best practices:
"Although ADD and COPY are functionally similar, generally speaking,
COPY is preferred. That’s because it’s more transparent than ADD.
[...] For other items (files, directories) that do not require ADD’s tar
auto-extraction capability, you should always use COPY."
Additionally, ADD commands were not cached prior to 0.7.3 (which was
released on 2013-01-02).
You can user `ENV` directive in Dockerfile to disable the installation
for some services or change `image/buildconfig`.
The flags are :
DISABLE_SSHD
DISABLE_CRON
DISABLE_SYSLOG
