How to change storage backend in Docker

Hello all,

I have been using Docker with the Devicemapper storage driver. After manually editing the launcher script, I finally took the time to convert to Overlay2. Here are the instructions I took to do this. I hope this helps others. I see others have asked the question, but I don’t see any answers. I used this excellent guide to help figure this out.

Step 1: Halt your Discourse application (and other docker apps)

./launcher stop app

Step 2: Commit and save your old Docker containers/images

We first committed each image we care for so that we had the most recent version tagged somewhere with all changes included. This can be done roughly like this:

docker ps -a
# for each container you care for, stop and then commit it
docker commit e198aac7112d export/local_discourse_app 
docker save export/local_discourse_app > export_local_discourse_app.tar.gz

Step 3: Change storage driver

I chose Overlay2, but the Discourse-recommended driver is aufs. Adjust as necessary. If something goes wrong, simply set the storage-driver to devicemapper as needed.

Insert the following into /etc/docker/daemon.json

{
  "storage-driver": "overlay2"
}

Step 4: Restart docker

sudo service docker restart

Step 5: Import image into new storage device

docker load < export_local_discourse_app.tar.gz

Step 6: Rebuild Discourse

./launcher rebuild app

I hope this helps! Feel free to suggest any modifications or questions.

15 Likes

Hello! Sorry for bumping but i’ve been using discourse like for 2 years and now im trying to get into its plugin development process.
I have a VPS with ubuntu 16.04 fresh installed and docker gets installed by default with devicemapper. There is no possibility to change it (This tutorial and everyone in google makes docker impossible to start) any clue?

Why Ubuntu 16.04, that is already quite out of date? Why not 18.04?

I’ve tried both of them and I think my VPS dont support that kernel or something. I have a better VPS in the same company and I have no problem…