How to save a Docker container state

Question

I\'m trying to learn the ins and outs of Docker, and I\'m confused by the prospect of saving an image.

I ran the basic Ubuntu image, installed Anaconda Python and a

Answer 1

It's possible (but not recommended) by using docker commit command.
You can check the following clear example:
https://phoenixnap.com/kb/how-to-commit-changes-to-docker-image

Answer 2

The usual way is at least through a docker commit: that will freeze the state of your container into a new image.

Note: As commented by anchovylegend, this is not the best practice, and using a Dockerfile allows you to formally modeling the image content and ensure you can rebuild/reproduce its initial state.

You can then list that image locally with docker images, and run it again.

Example:

$ docker ps

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS              NAMES
c3f279d17e0a        ubuntu:12.04        /bin/bash           7 days ago          Up 25 hours                            desperate_dubinsky
197387f1b436        ubuntu:12.04        /bin/bash           7 days ago          Up 25 hours                            focused_hamilton

$ docker commit c3f279d17e0a  svendowideit/testimage:version3

f5283438590d

$ docker images

REPOSITORY                        TAG                 ID                  CREATED             SIZE
svendowideit/testimage            version3            f5283438590d        16 seconds ago      335.7 MB

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After that, if you have deployed a registry server, you can push your image to said server.

Answer 3

Use a Docker file for these kind of scenarios.

An example case for an Ubuntu image with MongoDB:

FROM ubuntu
MAINTAINER Author name

RUN apt-key adv --keyserver keyserver.ubuntu.com --recv 7F0CEB10
RUN echo "deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist    10gen" | tee -a /etc/apt/sources.list.d/10gen.list
RUN apt-get update
RUN apt-get -y install apt-utils
RUN apt-get -y install mongodb-10gen

#RUN echo "" >> /etc/mongodb.conf

CMD ["/usr/bin/mongod", "--config", "/etc/mongodb.conf"]

Also see Best practices for writing Dockerfiles.