How to Create MongoDB cluster as Docker Containers

Question

I can able to run single instance on Mongo using the following Docker command

docker run -it --rm -d -p 27017:27017 --user mongodb mongo:3.4

But I can't find out how to configure Config Server and Query Router and also how add shards with Replication

Thanks in Advance

Solution 1

I used this tutorial myself: https://medium.com/@gargar454/deploy-a-mongodb-cluster-in-steps-9-using-docker-49205e231319#.mle6a8wmg

Step 1: create folders

create folders (local on all nodes):

sudo mkdir -p /dockerlocalstorage/data/mongodb
sudo mkdir -p /dockerlocalstorage/backup/mongodb
sudo mkdir -p /dockersharedstorage/config/mongodb/

Step 2: create keyfile

create keyfile as root user and give correct permissions:

sudo su
cd /dockersharedstorage/config/mongodb/
openssl rand -base64 741 > mongodb-keyfile
chmod 600 mongodb-keyfile
sudo chown 999 mongodb-keyfile

Depending on the mount type you might need to use /dockerlocalstorage/ to keep the certs. Mongodb will complain if the permissions are not set correctly (which could be harder to achieve on lets say a cifs mount)

Step 3: setup first node

create mongodb container without auth/keyfile:

docker run --name mongodb \
-v /dockerlocalstorage/data/mongodb:/data/db \
-v /dockersharedstorage/config/mongodb:/opt/keyfile \
--hostname="dock01" \
-p 27017:27017 \
-d mongo

log in to container:

docker exec -it mongodb mongo

create root users, dont forget to change the passwords

use admin
db.createUser( {
     user: "admin",
     pwd: "PASSWORD",
     roles: [ { role: "userAdminAnyDatabase", db: "admin" } ]
   });

db.createUser( {
     user: "root",
     pwd: "PASSWORD",
     roles: [ { role: "root", db: "admin" } ]
   });   

exit and remove the container

exit
docker stop mongodb
docker rm mongodb

Step 4: start nodes

change NODE_NR:

docker run \
-d \
--name mongodb \
-v /dockerlocalstorage/data/mongodb:/data/db \
-v /dockerlocalstorage/backup/mongodb:/data/backup \
-v /dockersharedstore/config/mongodb:/opt/keyfile \ 
--restart=always \
--hostname="dock01" \
-p 27017:27017 mongo \
--keyFile /opt/keyfile/mongodb-keyfile \
--replSet "SET_NAME"

Step 5: setup replication

connect to node 1:

docker exec -it mongodb mongo
use admin
db.auth("root", "PASSWORD");

initialize the replication set:

rs.initiate()

Check the replica set with: rs.conf() or rs.status()

add others:

rs.add("dock02:27017")
rs.add("dock03:27017")

Step 6: setup mongodump

edit crontab:

sudo su
crontab -l > tempcron

echo new cron into cron file

echo "0 4 * * *  docker exec -it mongodb mongodump -u root -p PASSWORD -o /data/backup/daily"  >> tempcron
echo "30 4 * * 5 docker exec -it mongodb mongodump -u root -p PASSWORD -o /data/backup/weekly" >> tempcron

install new cron file

crontab tempcron
rm tempcron
exit

Solution 2

You could use docker swarm mode if you want docker native mongodb cluster (Docker >= 1.12 needed).

Have a look at this nice tutorial. This will show you how to get a mongodb cluster with docker, replicated with Config Server. Basically, the steps are:

1. Create multiple virtual machines (with docker-machine or whatever you use to create a new docker host)
2. Create the swarm (docker cluster of multiple machines)
3. Create a swarm overlay network to deal with all your mongodb traffic
4. Create the services on each swarm node (that will create your mongodb containers on your hosts)
5. Configure your mongodb replica set

This is a bit of work, but worth it, as when you get there, you'll have tools on docker swarm to orchestrate your mongodb cluster.