Howto persist MongoDB - data of a running Docker c

Question

i have a running Mongo DB Container called xyz from offical Mongo Image. i created the container with docker run -d -p 21707:21707 mongo In this container i created 2 collections with sample data.

Now i want to extract this container in a new image on dockerhub.

I used docker commit and created a new image, pushed it on the docker hub. If i pull the image on a other system and create a new container from this image, there are no data like in my origin container xyz.

After research i found out that the mongo image could used with a volume, but i missed this step in the past... I think the container use /data/db as standard volume(docker inspect), on commit this volume is not attached to the new image?!

Also i tried docker export/import with the same problem mentioned above!

Now my Question, how could i reach to migrate this "xyz" running container with my sample data in a new image/container? Thanks a lot!

Answer 1

I used docker commit and created a new image, pushed it on the docker hub. If i pull the image on a other system and create a new container from this image, there are no data like in my origin container xyz.

The mongo docker image writes its data into a volume. As a result, those data won't be saved to a new docker image created with docker commit. docker export won't produce your data for the same reason.

how could i reach to migrate this "xyz" running container with my sample data in a new image/container?

What you want is either:

• create a new container re-using the first container's volume → see --volumes-from
• save the first container's volume data into a directory on your docker host, and create a new container mounting this directory into the container → the docker run -v option

Also, this SO question might help you figure out volumes.

Answer 2

I wanted to make an image to test things around authentication and I has the same issue. I solved it this way:

Dockerfile

FROM mongo

COPY setup.sh /
RUN chmod +x /setup.sh
RUN /setup.sh

ENTRYPOINT ["/usr/bin/mongod"]
CMD ["--auth", "--dbpath=/containerdb"]

setup.sh

#!/bin/bash

mkdir containerdb

mongod --auth --dbpath=/containerdb &

until mongo admin --eval 'db.createUser({"user":"root", "pwd":"password", "roles": [ "root" ] })'
do
  echo 'Mongo not yet ready, waiting 1 sec until retry'
  sleep 1
done

mongod --shutdown --dbpath=/containerdb

Bim! When you run this image you have a mongodb with authentication activated and a root user. The key is to workaround the VOLUME in the base Dockerfile by storing the data somewhere else.