How to run Mongo shell command after docker-compose?

Question

I would like to start this MongoDB Replica Set:

version: "3"

services:
  mongo1:
    image: mongo
    ports:
      - 27017:27017
    command: mongod --replSet rs0
  mongo2:
    image: mongo
    ports:
      - 27018:27017
    command: mongod --replSet rs0
  mongo3:
    image: mongo
    ports:
      - 27019:27017
    command: mongod --replSet rs0

Wait for those to come up, then access the Mongo shell via terminal:

docker exec -it mongo1 mongo

Then in Mongo shell do:

rs.initiate({"_id":"rs0","members":[{"_id":0,"host":"mongo1:27017"},{"_id":1,"host":"mongo2:27017"},{"_id":2,"host":"mongo3:27017"}]})

Mongo also allows mongo --eval "rs.initiate(..)", which may make things easier.

My question is how do I run this command after mongo1, mongo2, mongo3 are up?

What happens when you run this? I imagine you could set a container_name to make it easier? — Robert Seaman
– Robert Seaman, Commented May 25, 2018 at 22:45
It works if I just do it manually like that but I would like it to be automated to be deployed to the cloud. — atkayla
– atkayla, Commented May 25, 2018 at 23:33

ofekp · Accepted Answer · 2018-09-17 11:04:27Z

You can do this, I recently had to run mongo --repair then run the MongoDB itself and after the MongoDB is up I needed to add my user to the DB, you can easily change things to run commands only after all three MongoDBs are up.

Possible docker-compose.yml:

version: "2"
services:
  mongo:
    container_name: mongo
    restart: on-failure:10
    image: mongo
    environment:
      - MONGO_INITDB_ROOT_USERNAME=<user>
      - MONGO_INITDB_ROOT_PASSWORD=<pass>
      - MONGO_INITDB_DATABASE=db
    volumes:
      - ./data:/data/db
    ports:
      - "27017:27017"
    command: bash -c "mongod --repair && mongod"

  mongoClient:
    image: mongo
    container_name: mongoClient
    links:
      - mongo
    volumes:
      - ./deployment_scripts:/deployment_scripts
    command: 
      - /deployment_scripts/add_user.sh
    depends_on:
      - mongo

  app:
    container_name: app
    restart: always
    build: .
    volumes:
      - .:/usr/src/app
    ports:
      - "3000:3000"
    depends_on:
      - mongoClient
    links:
      - mongo

My /deployment_scripts/add_user.sh script wait for MongoDB to be up:

until mongo --host mongo --eval "print(\"waited for connection\")"
do
    sleep 1
done

// you can add more MongoDB waits here

echo "Adding user to MongoDB..."
mongo --host mongo --eval "db.createUser({ user: \"<user>\", pwd: \"<pass>\", roles: [ { role: \"root\", db: \"admin\" } ] });"
echo "User added."

Note that you can address all three of your MongoDBs by replacing --host mongo with your --host mongo1 --host mongo2 and --host mongo3. You'll use this for both of the eval commands in the script.

Credit to this SO answer https://stackoverflow.com/a/45060399/4295037 that I used (until mongo ...).

Koe · Accepted Answer · 2018-05-26 01:12:52Z

-1

I assume you are using Oficial Mongo image, that image is configured with:

ENTRYPOINT ["docker-entrypoint.sh"]
CMD ["mongod"]

If you check the docker-entrypoint.sh you will notice you could run any command you want by overwriting the CMD.

So, you can do for each mongo container

$ docker run -d mongo
9bf0473d491a2d7ae821bcf10ed08cd49678d28e46344589622bd9440a6aca65

$ docker ps -q
9bf0473d491a

$ docker exec -ti 9bf0473d491a mongo --eval "rs.initiate(.....)"
MongoDB shell version v3.6.5
connecting to: mongodb://127.0.0.1:27017
MongoDB server version: 3.6.5
{
    "ok" : 0,
    "errmsg" : "This node was not started with the replSet option",
    "code" : 76,
    "codeName" : "NoReplicationEnabled"
}

Notice that the errmsg is just because in my example the rs.initiate() is empty, it will work for you with the right config.

answered May 26, 2018 at 1:12

Koe

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3 Comments

atkayla Over a year ago

Hi there. I am sorry for the stupid question, but what exactly am I supposed to edit? Do you mean pull the image, edit the image, then commit my modified image? I was hoping I could just stick an easy command in my docker-compose somehow. Also I was just trying to do rs.initiate(...) once after all replicas are up, not for each replica.

Robert Seaman Over a year ago

@kaya I don't think mongo images are configurable in that sense using just docker-compose. I would advise using docker exec to configure after deployment. My guess is it would take some extensive work to be able to dynamically add a MongoDB Replica set using just docker-compose configuration.

Koe Over a year ago

@kayla , edit the rs.initiate(...) and replace the ... with your own json config to initiate the RS.

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