pm2 start app not working

I installed hubot rocket chat adapter. it works well. I want to use pm2 to start it forever. so i created a pm2.json file under my hubot directory myhubot as the following:

{
  "apps": [{
        "name": "myhubot",
        "max_memory_restart": "1024M",
        "log_date_format": "YYYY-MM-DD HH:mm:ss SSS",
        "script": "bin/hubot", 
        "exec_interpreter": "bash",
        "args": "--name myhubot --adapter rocketchat",
        "watch": ["package.json", "external-scripts.json", "scripts/", "hubot-scripts.json", "HUBOT_GITHUB_EVENT_NOTIFIER_TYPES=issues,pull_request,push bin/hubot"],
        "out_file": "/var/log/hubot/app.log",
        "error_file": "/var/log/hubot/err.log",
        "port": "8079",
        "env": {
            "ROCKETCHAT_URL": "my website domain",
            "ROCKETCHAT_USER": "bot",
            "ROCKETCHAT_ROOM": "",
            "ROCKETCHAT_PASSWORD": "bot",
            "PORT": "8079",
            "HUBOT_GITHUB_EVENT_NOTIFIER_TYPES": "issues,pull_request,push"
        }
    }]
}

I installed pm2 and pm2 works well. then i did sudo pm2 start pm2.json. pm2 does started an app named myhubot based on command line. But when i went to rocket.chat, hubot is not logged in. Is there anything wrong? Is port 8079 right? can the port be any number from 3001-8080?

RocketChat / Rocket.Chat.Hubot

pm2 start app not working #6