Can't connect to db

[ralyodio]

node_modules/koa-mongoose/lib/mongoose.js:68
    db.open(options.host, database, options.port, options)
       ^

app.use(mongoose({
    user: MONGO_USER,
    pass: MONGO_PASS,
    host: MONGO_HOST,
    port: MONGO_PORT,
    database: MONGO_DB,
    mongodbOptions:{
        poolSize: 5,
        native_parser: true
    }
}));