Installing the Node Checker

It is recommended to install the Node Checker on a dedicated instance which will run continuously to monitor a Red5 Pro autoscale environment. Depending on how many concurrent checks you want to run, you will want at least 2 CPUs/4G memory for that instance.

IMPORTANT: at this time, the node checker can not be run if your environment has multiple nodegroups

1 - Install Google Chrome, Node.js and other prerequisites with the following commands:

sudo apt-get update
wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
sudo apt install ./google-chrome-stable_current_amd64.deb
curl -sL https://deb.nodesource.com/setup_12.x -o nodesource_setup.sh
sudo bash nodesource_setup.sh
sudo apt-get install -y nodejs
sudo apt-get install build-essential
sudo npm install forever -g

2 - Download the entire Node Checker repository: git clone https://github.com/red5pro/nodejs-checker

3 - cd into the nodejs-checker directory, and install dependencies by running npm install

If you are logged in as the root user you will need to create a new user to run the Node Checker server. That is because the Node Checker internally starts a Chrome process but Chrome will not start for security reasons if the Node Checker is running under the root user. To add a new user in Ubuntu run adduser userNameHere. Enter password and other needed info to create a user account on the Ubuntu server. You will then need to su userNameHere to run the following as your new user.

4 - The Node Checker server can then be started with the following command:

PORT=<Node-Checker-Port> SM_HOST=https://<Hostname-of-Stream-Manager> SM_TOKEN=<Token-Of-Stream-Manager> MAX_SUBSCRIBE_RETRIES=<Max-Retries> MAX_FAILURES=<Max-Failures> CHECK_INTERVAL=<Check-Interval> TIMEOUT=<Timeout> CONCURRENTCHECKS=<Concurrent-Checks> forever start index.js

If you want to stop the process, type forever stop index.js


  • PORT = The Port used by the Node Checker server - defaults to 8001.
  • SM_HOST = The Hostname of the Stream Manager including https://.
  • SM_TOKEN = The rest.administratorToken of your Stream Manager.
  • MAX_SUBSCRIBE_RETRIES = The number of times the nodechecker will retry to subscribe to the provided live stream using the provided edge before reporting it as bad to the Node Checker server - defaults to 3.
  • MAX_FAILURES = The number of health checks that a node can fail before being reported to the Stream Manager - defaults to 2. It should be noted that the player may try to subscribe just before a stream is unpublished, and thus making the edge fail the health check as a result. Therefore, it is recommended to check at least twice before reporting to the Stream Manager. Every time a node has a good health check (it can successfully subscribe), the health check failure counter of the node is reset to 0.
  • CHECK_INTERVAL = The period of the health checks in milliseconds - defaults to 30,000 milliseconds (30 seconds).
  • TIMEOUT = The maximum time in milliseconds given to the Chrome Instance to report if it could subscribe or not - defaults to 15000 milliseconds.
  • CONCURRENTCHECKS = The maximum number of edges that the Node Checker server can check at the same time - defaults to 5.

It should be noted that the server will create {CONCURRENTCHECKS} Chrome instances at the same time. If there are more edges than {CONCURRENTCHECKS}, then they will be divided in groups of size smaller or equal to {CONCURRENTCHECKS}. When there is more than one check group, the Node Checker server may increase the value of {CHECKINTERVAL} to guarantee that there are never more than {CONCURRENTCHECKS} Google Chrome instances at any given time. In general CHECK-INTERVAL > ((# of edges / {CONCURRENTCHECKS}) * {TIMEOUT}). For example, if your nodegroup has 10 edges, and you set the CONCURRENTCHECKS value to 5, then the checks will be run against half of the edge servers every

Example: PORT=8001 SM_HOST=https://my.streammanager.com SM_TOKEN=xyz123 MAX_SUBSCRIBE_RETRIES=3 MAX_FAILURES=2 CHECK_INTERVAL=30000 TIMEOUT=15000 CONCURRENTCHECKS=5 forever start index.js

Nodechecker Logging

To view the log output, type forever list. That will return the path where the log is written