express app listen if mongodb is up and re-establish connection

i have this code that opens up a connection to mongodb:

db_connect_mongo = init: (callback) ->
  self = this
  mongo_options = db:
      safe: true
  mongoose.connect DB_URL, mongo_options
  db = self.db_mongo = mongoose.connection

  db.on "error", (error) ->
    logger.error "ERROR connecting to: " + DB_URL, logCategory
    callback error, null

  db.on "connected", ->
    logger.info "SUCCESSFULLY connected to: " + DB_URL, logCategory
    callback true, db

  db.on "disconnected", ->
    logger.info "DISCONNECTED from the database: " + DB_URL, logCategory

# check and connect to Redis

exports = module.exports = db_connect_mongo

i then call this in my app.coffee like:

#Connect to database
dbconnection = require "./utils/dbconnect"
dbconnection.init (result) ->
  logger.info "Database initialized: " + result, logCategory

when i shut down the mongo db, i get a info: [DATABASE Connection] DISCONNECTED from the database: mongodb://127.0.0.1:27017/zmgc-mongo so in my logger.coffee i would like to 'listen' if the mongodb comes up so that a connection be made.

what would be a good approach to catch all the events of de/re-connection to the db?