Go-Sync-Mongo

Simple tool that polls operations from the replication oplog of a remote server, and applies them to the local/remote server. This capability supports certain classes of real-time migrations that require that the source server remain online and in operation throughout the migration process.

To see list of commands available use:

$ go run main.go --help

Typically this command will take the following form:

$ go run main.go sync --src "mongodb://localhost:27018" --src-username mongooplog --src-password some-password --src-ssl=false --dst "mongodb://localhost:27019" --dst-username mongooplog --dst-password some-password --dst-ssl=false

This command copies oplog entries from the mongod instance running on the host mongodb0.example.net and duplicates operations to the host mongodb1.example.net. If you do not need to keep the --src host running during the migration, consider using mongodump and mongorestore or another backup operation, which may be better suited to your operation.

Running and testing with docker

start two mongo services:

$ docker run --name mongo1 -p 27018:27017 -d mongo mongod --logpath ./tmp/1.log --port 27017 --replSet rs
$ docker run --name mongo2 -p 27019:27017 -d mongo mongod --logpath ./tmp/1.log --port 27017 --replSet rs

set up replication, user and permissions for mongo1 server

$ docker exec -it mongo1 mongo admin
> rs.initiate({_id: 'rs', members: [ {_id: 1, host:'localhost:27017'}]})
> db.createUser({ user: 'mongooplog', pwd: 'some-password', roles: [ { role: "userAdminAnyDatabase", db: "admin" } ] });
> db.createRole( 
{ 
    role: "anyAction", 
    privileges: [ { 
        resource: { anyResource: true }, 
        actions: [ "anyAction" ] } ], 
    roles: []
})
> db.grantRolesToUser("mongooplog",["anyAction"])

set up replication, user and permissions for mongo2 server

$ docker exec -it mongo2 mongo admin
> rs.initiate({_id: 'rs', members: [ {_id: 1, host:'localhost:27017'}]})
> db.createUser({ user: 'mongooplog', pwd: 'some-password', roles: [ { role: "userAdminAnyDatabase", db: "admin" } ] });
> db.createRole( 
{ 
    role: "anyAction", 
    privileges: [ { 
        resource: { anyResource: true }, 
        actions: [ "anyAction" ] } ], 
    roles: []
})
> db.grantRolesToUser("mongooplog",["anyAction"])

start mongo oplog sync:

$ go run main.go sync --src "mongodb://localhost:27018" --src-username mongooplog --src-password some-password --src-ssl=false --dst "mongodb://localhost:27019" --dst-username mongooplog --dst-password some-password --dst-ssl=false

Try adding, deleting and modify some records in mongo1 server and check if they persist in mongo2 server. You can also use the status command to check the record count in each cluster.

$ go run main.go status --src "mongodb://localhost:27018" --src-username mongooplog --src-password some-password --src-ssl=false --dst "mongodb://localhost:27019" --dst-username mongooplog --dst-password some-password --dst-ssl=false
+--------+--------+-------------+------+
|   DB   | SOURCE | DESTINATION | DIFF |
+--------+--------+-------------+------+
| checkr |      1 |           1 |    0 |
+--------+--------+-------------+------+

Releases

You can download binary releases for linux, macos and windows here