If you install MongoDB from Ubuntu 14.04 LTS, there’s a few steps that you need to take to enable the oplog for use with Meteor.
To enable the oplog, we need to enable replication. We’re not actually going to replicate to any other servers.
In /etc/mongodb.conf, add
replSet = rs0
Restart mongodb:
service mongodb restart
As root, run mongo to get a shell. Run:
rs.initiate({_id:"rs0", members: [{"_id":1, "host":"127.0.0.1:27017"}]})
You should see something like:
{
"info" : "Config now saved locally. Should come online in about a minute.",
"ok" : 1
}
You can run rs.conf() and rs.status() for more information.
Switch to the admin database with:
rs0:PRIMARY> use admin
then create the user:
rs0:PRIMARY> db.addUser({user: "oplogger", pwd: "password", roles: [], otherDBRoles: {local: ["read"]}})
In your Meteor environment settings, add:
MONGO_OPLOG_URL=mongodb://oplogger:[email protected]/local?authSource=admin
If you’re using my setup with Meteor running in Docker containers on AWS machines, you need to use the host IP like so:
MONGO_OPLOG_URL=mongodb://oplogger:[email protected]/local?authSource=admin
Note that you must use the local database, not whatever your application is configured for. Also note that this has security implications if you intend run separate applications on the same database server.
It it comes up without errors, that’s a really good sign!
There’s some advice at https://github.com/meteor/docs/blob/version-NEXT/long-form/oplog-observe-driver.md but it’s pretty old and requires you to change your application. To be continued!