Initialize data on dockerized mongo
First create a docker volume
docker volume create --name mongostore
then create your mongo container
docker run -d --name mongo -v mongostore:/data/db mongo:latest
The -v
switch here is responsible for mounting the volume mongostore
at the /data/db
location, which is where mongo saves its data. The volume is persistent (on the host). Even with no containers running you will see your mongostore volume listed by
docker volume ls
You can kill the container and create a new one (same line as above) and the new mongo container will pick up the state of the previous container.
Initializing the volume Mongo initializes a new database if none is present. This is responsible for creating the initial data in the mongostore. Let's say that you want to create a brand new environment using a pre-seeded database. The problem becomes how to transfer data from your local environment (for instance) to the volume before creating the mongo container. I'll list two cases.
Local environment
You're using either Docker for Mac/Windows or Docker Toolbox. In this case you can easily mount a local drive to a temporary container to initialize the volume. Eg:
docker run --rm -v /Users/myname/work/mongodb:/incoming \ -v mongostore:/data alpine:3.4 cp -rp /incoming/* /data
This doesn't work for cloud storage. In that case you need to copy the files.
Remote environment (AWS, GCP, Azure, ...)
It's a good idea to tar/compress things up to speed the upload.
tar czf mongodata.tar.gz /Users/myname/work/mongodb
Then create a temporary container to untar and copy the files to the mongostore. the
tail -f /dev/null
just makes sure that the container doesn't exit.docker run -d --name temp -v mongostore:/data alpine:3.4 tail -f /dev/null
Copy files to it
docker cp mongodata.tar.gz temp:.
Untar and move to the volume
docker exec temp tar xzf mongodata.tar.gz && cp -rp mongodb/* /data
Cleanup
docker rm temp
You could also copy the files to the remote host and mounting from there but I tend to avoid interacting with the remote host at all.
Disclaimer. I'm writing this from memory (no testing).
A more self-contained approach:
- create javascript files that initialize your database
- create a derived MongoDB docker image that contains these files
There are many answers that use disposable containers or create volumes and link them, but this seems overly complicated. If you take a look at the mongo docker image's docker-entrypoint.sh, you see that line 206 executes /docker-entrypoint-initdb.d/*.js
files on initialization using a syntax: mongo <db> <js-file>
. If you create a derived MongoDB docker image that contains your seed data, you can:
- have a single docker run command that stands up a mongo with seed data
- have data is persisted through container stops and starts
- reset that data with docker stop, rm, and run commands
- easily deploy with runtime schedulers like k8s, mesos, swarm, rancher
This approach is especially well suited to:
- POCs that just need some realistic data for display
- CI/CD pipelines that need consistent data for black box testing
- example deployments for product demos (sales engineers, product owners)
How to:
- Create and test your initialization scripts (grooming data as appropriate)
Create a Dockerfile for your derived image that copies your init scripts
FROM mongo:3.4 COPY seed-data.js /docker-entrypoint-initdb.d/
Build your docker image
docker build -t mongo-sample-data:3.4 .
Optionally, push your image to a docker registry for others to use
Run your docker image
docker run \ --name mongo-sample-data \ -p 27017:27017 \ --restart=always \ -e MONGO_INITDB_DATABASE=application \ -d mongo-sample-data:3.4
By default, docker-entrypoint.sh will apply your scripts to the test
db; the above run command env var MONGO_INITDB_DATABASE=application
will apply these scripts to the application
db instead. Alternatively, you could create and switch to different dbs in the js file.
I have a github repo that does just this - here are the relevant files.
with the latest release of mongo docker , something like this works for me.
FROM mongo
COPY dump /home/dump
COPY mongo_restore.sh /docker-entrypoint-initdb.d/
the mongo restore script looks like this.
#!/bin/bash
# Restore from dump
mongorestore --drop --gzip --db "<RESTORE_DB_NAME>" /home/dump
and you could build the image normally.
docker build -t <TAG> .