session-52.txt

FROM -> refer base OS
RUN -> to configure image
CMD -> command executed at the time of container creation
LABEL -> metadata of the image
EXPOSE -> port information
ADD -> same as COPY but 2 extra capabilities. can download content directly from internet and untar the file
COPY -> copy the files from local to image
USER -> to mention the user that container should be running on
WORKDIR -> working directory of the image/container
ENV -> env variables to the container
ARG -> variables at build time, cant be accessed inside container. ARG can be first instruction before 	FROM to supply the version
ENTRYPOINT -> command to be executed while creating container. it cant be overridden, if we try it will go append. CMD can be overridden. CMD can supply default args for ENTRYPOINT. we can always override default args

ONBUILD
=======
our image can be used by someone else. but we want to put some conditions to use our image. that can be enforced using ONBUILD instruction..

our nginx image expects index.html while it is used by others.

OS -> 8,9,10, etc..
configurations -> packages update
programming languages -> nodejs 20,21, etc..

Ansible

docker uses by default bridge network
default bridge network containers can't communicate with each other..

you should create your own bridge network


roboshop bridge: 172.18.0.1
172.18.0.2
172.18.0.3

when you install docker, it creates one bridge network with name also as bridge
by default containers get IP address from this network with name bridge
if you use default bridge network you cant communicate between the containers using names
you should create your own bridge network