mongodb


mongodump and mongorestore Between Docker-composed Containers

I’m trying to refine the process by which I backup and restore Dockerized MongoDB containers. My previous effort is basically a brute-force copy-and-paste job on the container’s data directory. It works, but I’m concerned about restoring data between containers installed with different versions of MongoDB. Apparently this is tricky enough even with the benefit of recovery tools like mongodump and mongorestore, which is what I’m using below.

In short, I need to dump my data from a data-only MongoDB container, bundle the files uploaded to my Express application, and restore it all on another server. Here’s how I did it…

Dump the data

I’m a big fan of docker-compose. I use it to manage all my containers. The following method requires that the composition be running so that mongodump can be run against the running Mongo container (which, in turn, accesses the data-only container). Assuming the name of the container is myapp_mongo_1

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docker run --rm --link myapp_mongo_1:mongo -v $(pwd)/myapp-mongo-dump:/dump mongo bash -c 'mongodump --host $MONGO_PORT_27017_TCP_ADDR'

This will create a root-owned directory called myapp-mongo-dump in your current directory. It contains all the BSON and JSON meta-data for this database. For convenience, I change ownership of this resource:

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sudo chown -R user:user myapp-mongo-dump

Then, for transport, I archive the directory:

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tar zcvf myapp-mongo-dump.tar.gz myapp-mongo-dump

Archive the uploaded files

My app allows file uploads, so the database is pointing to a bunch of files stored on the file system. My files are contained in a directory called uploads/.

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tar zcvf uploads.tar.gz uploads

Now I have two archived files: myapp-mongo-dump.tar.gz and uploads.tar.gz.

Transfer backup to the new server

Here I use scp:

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scp myapp-mongo-dump.tar.gz uploads.tar.gz user@example.com:~

Restore the files

In the previous command, for simplicity, I transferred the files into the user’s home folder. These will need to be moved into the root of the project folder on the new server. Once there, assuming the same app has been setup and deployed, I first unpack the uploaded files:

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tar zxvf uploads.tar.gz
tar zxvf myapp-mongo-dump.tar.gz

Then I restore the data to the data-only container through the running Mongo instance (assumed to be called myapp_mongo_1):

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docker run --rm --link myapp_mongo_1:mongo -v $(pwd)/myapp-mongo-dump:/dump mongo bash -c 'mongorestore --host $MONGO_PORT_27017_TCP_ADDR'

With that, all data is restored. I didn’t even have to restart my containers to begin using the app on its new server.


MongoDB backup and restore between Dockerized Node apps

My bargain-basement cloud service provider, CloudAtCost recently lost one of my servers and all the data on it. This loss was exasperated by the fact that I didn’t backup my MongoDB data somewhere else. Now I’m working out the exact process after the fact so that I don’t suffer this loss again (it’s happened twice now with CloudAtCost, but hey, the price is right).

The following is a brute-force backup and recovering process. I suspect this approach has its weaknesses in that it may depend upon version-consistency between the MongoDB containers. This is not ideal for someone like myself who always installs the latest version when creating new containers. I aim to develop a more flexible process soon.

Context

I have a server running Ubuntu 16.04, which, in turn is serving up a Dockerized Express application (Nginx, MongoDB, and the app itself). The MongoDB data is backed up in a data-only container. To complicate matters, the application allows file uploads, which are being stored on the file system in the project’s root.

I need to dump the data from the data-only container, bundle the uploaded files, and restore it all on another server. Here’s how I did it…

Dump the data

I use docker-compose to manage my containers. To obtain the name of the MongoDB data-only container, I simply run docker ps -a. Assuming the name of the container is myapp_mongo_data

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docker run --volumes-from myapp_mongo_data -v $(pwd):/backup busybox tar cvf /backup/backup.tar /data/db

This will put a file called backup.tar in the app’s root directory. It may belong to the root user. If so, run sudo chown user:user backup.tar.

Archive the uploaded files

The app allows file uploads, so the database is pointing to a bunch of files stored on the file system. My files are contained in a directory called uploads/.

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tar -zcvf uploads.tar.gz uploads

Now I have two archived files: backup.tar and uploads.tar.gz.

Transfer backup to the new server

Here I use scp:

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scp backup.tar uploads.tar.gz user@example.com:~

Restore the files

In the previous command, for simplicity, I transferred the files into the user’s home folder. These will need to be moved into the root of the project folder on the new server. Once there, assuming the same app has been setup and deployed, I first unpack the uploaded files:

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tar -zxvf uploads.tar.gz

Then I restore the data to the data container:

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docker run --volumes-from myapp_mongo_data -v $(pwd):/backup busybox tar xvf /backup/backup.tar

Remove and restart containers

The project containers don’t need to be running when you restore the data in the previous step. If they are running, however, once the data is restored, remove the running containers and start again with docker-compose:

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docker-compose stop
docker-compose rm
docker-compose up -d

I’m sure there is a reasonable explanation as to why removing the containers is necessary, but I don’t know what it is yet. In any case, removing the containers isn’t harmful because all the data is on the data-only container anyway.

Warning

As per the introduction, this process probably depends on version consistency between MongoDB containers.