I want to create a Docker container with an instance of Mongo. In particular, I would like to create a replica set with only one node (since I'm interested in transactions and they are only available for replica sets).
Dockerfile
FROM mongo
RUN echo "rs.initiate();" > /docker-entrypoint-initdb.d/replica-init.js
CMD ["--replSet", "rs0"]
docker-compose.yml
version: "3"
services:
db:
build:
dockerfile: Dockerfile
context: .
ports:
- "27017:27017"
If I use the Dockerfile alone everything is fine, while if I use docker-compose it does not work: in fact if I then log to the container I got prompted as rs0:OTHER>
instead of rs0:PRIMARY>
.
I consulted these links but the solutions proposed are not working:
https://github.com/docker-library/mongo/issues/246#issuecomment-382072843 https://github.com/docker-library/mongo/issues/249#issuecomment-381786889
You still need to issue replSetInitiate even if there's only one node in the RS.
See also here .
This is the compose file I have used for a while now for local development. You can remove the keyfile
pieces if you don't need to connect via SSL.
version: "3.8"
services:
mongodb:
image : mongo:4
container_name: mongodb
hostname: mongodb
restart: on-failure
environment:
- PUID=1000
- PGID=1000
- MONGO_INITDB_ROOT_USERNAME=mongo
- MONGO_INITDB_ROOT_PASSWORD=mongo
- MONGO_INITDB_DATABASE=my-service
- MONGO_REPLICA_SET_NAME=rs0
volumes:
- mongodb4_data:/data/db
- ./:/opt/keyfile/
ports:
- 27017:27017
healthcheck:
test: test $$(echo "rs.initiate().ok || rs.status().ok" | mongo -u $${MONGO_INITDB_ROOT_USERNAME} -p $${MONGO_INITDB_ROOT_PASSWORD} --quiet) -eq 1
interval: 10s
start_period: 30s
command: "--bind_ip_all --keyFile /opt/keyfile/keyfile --replSet rs0"
volumes:
mongodb4_data:
It uses Docker's health check (with a startup delay) to sneak in the rs.initiate()
if it actually needs it after it's already running.
To create a keyfile.
Mac:
openssl rand -base64 741 > keyfile
chmod 600 keyfile
Linux:
openssl rand -base64 756 > keyfile
chmod 600 keyfile
sudo chown 999 keyfile
sudo chgrp 999 keyfile
I had to do something similar to build tests around ChangeStreams which are only available when running mongo as a replica set. I don't remember where I pulled this from, so I can't explain it in detail but it does work for me. Here is my setup:
Dockerfile
FROM mongo:5.0.3
RUN echo "rs.initiate({'_id':'rs0', members: [{'_id':1, 'host':'127.0.0.1:27017'}]});" > "/docker-entrypoint-initdb.d/init_replicaset.js"
RUN echo "12345678" > "/tmp/key.file"
RUN chmod 600 /tmp/key.file
RUN chown 999:999 /tmp/key.file
CMD ["mongod", "--replSet", "rs0", "--bind_ip_all", "--keyFile", "/tmp/key.file"]
docker-compose.yml
version: '3.7'
services:
mongo:
build: .
restart: always
ports:
- 27017:27017
healthcheck:
test: test $$(echo "rs.initiate().ok || rs.status().ok" | mongo -u admin -p pass --quiet) -eq 1
interval: 10s
start_period: 30s
environment:
MONGO_INITDB_ROOT_USERNAME: admin
MONGO_INITDB_ROOT_PASSWORD: pass
MONGO_INITDB_DATABASE: test
Run docker-compose up
and you should be good.
Connection String: mongodb://admin:pass@localhost:27017/test
Note: You shouldn't use this in production obviously, adjust the key "12345678" in the Dockerfile if security is a concern.
If you just need single node replica set of MongoDB via docker-compose.yml you can simply use this:
mongodb:
image: mongo:5
restart: always
command: ["--replSet", "rs0", "--bind_ip_all"]
ports:
- 27018:27017
healthcheck:
test: mongo --eval "rs.initiate()"
start_period: 5s
The top answer stopped working for me in later MongoDB and Docker versions. Particularly because rs.initiate().ok
would throw an error if the replica set was already initiated, causing the whole command to fail. In addition, connecting from another container was failing because the replica set's sole member had some random host, which wouldn't allow the connection. Here's my new docker-compose.yml
:
services:
web:
# ...
environment:
DATABASE_URL: mongodb://root:root@db/?authSource=admin&tls=false
db:
build:
context: ./mongo/
environment:
MONGO_INITDB_ROOT_USERNAME: root
MONGO_INITDB_ROOT_PASSWORD: root
ports:
- '27017:27017'
volumes:
- data:/data/db
healthcheck:
test: |
test $$(mongosh --quiet -u root -p root --eval "try { rs.initiate({ _id: 'rs0', members: [{ _id: 0, host: 'db' }] }).ok } catch (_) { rs.status().ok }") -eq 1
interval: 10s
start_period: 30s
volumes:
data:
Inside ./mongo/
, I have a custom Dockerfile
that looks like:
FROM mongo:6
RUN echo "password" > /keyfile \
&& chmod 600 /keyfile \
&& chown 999 /keyfile \
&& chgrp 999 /keyfile
CMD ["--bind_ip_all", "--keyFile", "/keyfile", "--replSet", "rs0"]
This Dockerfile
is suitable for development, but you'd definitely want a securely generated and persistent keyfile
to be mounted in production (and therefore strike the entire RUN
command).
This one works fine for me:
version: '3.4'
services:
ludustack-db:
container_name: ludustack-db
command: mongod --auth
image: mongo:latest
hostname: mongodb
ports:
- '27017:27017'
env_file:
- .env
environment:
- MONGO_INITDB_ROOT_USERNAME=${MONGO_INITDB_ROOT_USERNAME}
- MONGO_INITDB_ROOT_PASSWORD=${MONGO_INITDB_ROOT_PASSWORD}
- MONGO_INITDB_DATABASE=${MONGO_INITDB_DATABASE}
- MONGO_REPLICA_SET_NAME=${MONGO_REPLICA_SET_NAME}
healthcheck:
test: test $$(echo "rs.initiate().ok || rs.status().ok" | mongo -u $${MONGO_INITDB_ROOT_USERNAME} -p $${MONGO_INITDB_ROOT_PASSWORD} --quiet) -eq 1
interval: 60s
start_period: 60s
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