How to run Mongo shell command after docker-compose? - mongodb

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?

Answer 1

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 ...).

Answer 2

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.