Configuring MongoDB replica set from docker-compose - mongodb

Question

I'm using docker-compose to start 3 MongoDB servers which should be in a replica set.
I first start 3 MongoDB servers, then I configure the replica set.
This is how I would do the replica set config in a bash script:
mongo --host 127.0.0.1:27017 <<EOF
var cfg = {
"_id": "rs",
"version": 1,
"members": [
{
"_id": 0,
"host": "127.0.0.1:27017",
"priority": 1
},
// snip...
]
};
rs.initiate(cfg);
rs.reconfig(cfg)
EOF
Here I'm trying to replicate the configuring of the replica set using docker-compose.
# docker-compose.yml
mongosetup:
image: mongo:3.0
links:
- mongo1:mongo1
command: echo 'var cfg = { "_id": "rs", "version": 1, "members": [ { "_id": 0, "host": "127.0.0.1:27017", "priority": 1 }, { "_id": 1, "host": "mongo2:27017", "priority": 1 },{ "_id": 2, "host": "mongo2:27017", "priority": 1 } ] }; rs.initiate(cfg);' | mongo mongo1
Unfortunately that creates this error: yaml.scanner.ScannerError: mapping values are not allowed here.
What's the recommended approach?
Is it possible to store the cfg object in a separate file that docker-compose reads?

Answer 1

I fixed the problem by putting the config in setup.sh which I called from entrypoint.
mongosetup:
image: mongo:3.0
links:
- mongo1:mongo1
- mongo2:mongo2
- mongo3:mongo3
volumes:
- ./scripts:/scripts
entrypoint: [ "/scripts/setup.sh" ]
setup.sh
#!/bin/bash
MONGODB1=`ping -c 1 mongo1 | head -1 | cut -d "(" -f 2 | cut -d ")" -f 1`
mongo --host ${MONGODB1}:27017 <<EOF
var cfg = {
"_id": "rs",
"version": 1,
"members": [
{
"_id": 0,
"host": "${MONGODB1}:27017",
[cut..]
EOF
I have created a setup with docker-compose that starts 3 MongoDBs in a replica set and ElasticSearch with mongodb-river.
It's available at https://github.com/stabenfeldt/elastic-mongo