session-50.txt

docker build -t url/username/image:version .

docker build image:version .

docker tag image:version url/username/image:version

docker login

docker push image:version url/username/image:version

RUN vs CMD
---------------
systemctl start catalogue

it will create one nodejs process and this process will run for infinte time...

CMD instruction is to make your container running..

RUN --> runs at the time of image building
CMD --> runs at the time container creation

every container is a process.

systemctl commands will not work in containers...

command should be foreground and attach to the screen, then you send it into background

100 shopping covers all are white, you know only when you open them

you can give some lables to them to identify easily

COPY vs ADD
--------------
both are used to copy the files from local to image... but ADD have 2 extra capabilities

1. It can directly download files from internet
2. It can directly untar the tar files..

CMD vs ENTRYPOINT
-----------------
1. CMD command can be overridden by another command at run time.
ping google.com ping yahoo.com
2. ENTRYPOINT command can't be overridden, if you try to do so, the command you are entering at run time will go and append to ENTRYPOINT

We can use CMD and ENTRYPOINT for best results

1. You can use CMD instruction to supply default arguements to ENTRYPOINT
2. user can always override CMD arguements from run time

ARG vs ENV
-----------------
ARG instruction can provide values to the Dockerfile only at buildtime. ENV variables have access in the container

How can I use ARG variables inside container?
Assign the values of ARG to ENV variables so that you can access them inside container as well

ARG instruction can be used before FROM instruction to provide values to FROM instruction.

ARG value deffnied before FROM will not be accessed after FROM

ONBUILD
-----------------
author of image: I want to force users of image to follow something