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I need to create a Docker image with a large database. The database can be populated using a script populate_net_db.sh from specified folders. I need to create a Docker image that has this done at build time so that developers working with database can create a container and not wait long time before the database gets populated.

What I have done (this worked but is not what I need):

  • I can create database at run time and populate it using mysql Docker image and putting the required files into docker-entrypoint-initdb.d folder. This will require significant time to set things up when you run the image, but works as needed and I can access the DB with docker exec -it "image_name" mysql -u root -p exactly as required.

  • I can create the same database at build time using RUN command and see that the tables are set up correctly at build, however, when I run such an image a new mysql DB is set up and the DB from build is gone.

Is there a way to have the build-time database show up in docker exec -it "image_name" mysql -u root -p?

Nicholas Stepanov
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    Possible duplicate of [How to create populated MySQL Docker Image on build time](https://stackoverflow.com/questions/32482780/how-to-create-populated-mysql-docker-image-on-build-time) – David Maze Feb 19 '19 at 12:00
  • Short answer: because the MySQL base image use a `VOLUME` declaration for their data directory, you cannot build an image later that has any content there; it is stuck forever at the (empty) contents at the time `VOLUME` ran. – David Maze Feb 19 '19 at 12:01
  • On [another question](https://stackoverflow.com/questions/52546775/how-to-use-docker-compose-to-restore-fresh-databases-quickly-for-integration-tes/52546871#52546871) at one point I had suggested using `docker run -v` to keep the MySQL data in a host directory and sharing a tar file of that directory. – David Maze Feb 19 '19 at 12:12

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I managed to solve this problem by saving the contents of /var/lib/mysql/ in a temporary folder during build as: mv /var/lib/mysql /mnt/tmp/. Then I created an entrypoint script to put in /docker-entrypoint-initdb.d folder. This script deletes the /var/lib/mysql/ contents at run time and moves the saved state from /mnt/tmp/. This causes MySQL to restart. However, the database becomes available very fast at container run. This method takes ~5 minutes for a 27GB database versus >1hr with loading the database from a dump file.

Nicholas Stepanov
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