I want to create an image A in one instance/server, but in that instance there is no internet connection.
So can I create an image B with all packages installed at my machine and then Push to x.x.x.x and use it in image A as the FROM tag?
It will look like :
FROM x.x.x.x/B:latest
RUN ***
ENTRYPOINT
Please suggest a correct solution for this problem.
Short answer - of course, you can. You can use any image, including your own, to build new images.
Long answer - consider Docker multistage build for you purpose. This allows reduce the amount of images and the space occupied by your docker registry.
You can read more on https://docs.docker.com/develop/develop-images/multistage-build/
In short - you create a single Dockerfile where you define several images, based on each other. In case you don't need your base image outside from derived, this is your case. Following example will illustrate:
Dockerfile
# First create base image
FROM foo:latest as mybase # note we tag it 'mybase'
RUN blahblah
FROM mybase # here we derive new image, note Dockerfile is same!
RUN blahblahblah