session-51.txt

ENTRYPOINT

CMD instruction can be overriden
same instruction trying to override with ENTRYPOINT is not working

ping -c5 google.com ping -c5 yahoo.com

you can't override ENTRYPOINT, if you try to do it will go append

CMD vs ENTRYPOINT
----------------
you can mix CMD and entrypoint for better results

ping -c5

CMD is used to supply default arguements to ENTRYPOINT, we can always override default args from runtime.

USER
-----------
you should not let containers running with root access

ARG
-----------
1. ARG can be first instruction in only one case. It can be used to supply the version for FROM instruction
2. You can have args in Dockerfile, you can supply the values through command through option --build-args
3. You can always have default values to arg and override if required.


ENV vs ARG
-----------
1. ENV variables can be accessed both at the time build time and containers
2. ARG instruction can only be accessed at the time of build or image

How can I access arg inside container?

http://daws78s.online

index.html --> nginx welcome page

ONBUILD
----------
this is useful as a trigger, if some one is trying to use your image. you can force them to keep somefiles in their workspace or some configuration

MYSQL:8
---------
MySQL developers would have chosen some OS, ubuntu, debian, centos, rhel, etc.

FROM ubuntu:20
RUN apt install mysql-server

Database is created first. We should load default data.