Doppler – A Zero Configuration Remote Monitoring Tool

A while ago, we have written about Netdata, a lightweight, real-time performance and health monitoring tool for systems and applications. It monitors almost everything in a system and displays the result in a nice graphical layout in the web browser. Netdata requires no configuration and no dependencies either. It just works out of the box. Today, I stumbled upon a similar utility. Say hello to Doppler, a zero configuration remote monitoring tool for Linux systems. Just like Netdata, Doppler is also lightweight and it doesn't require any additional configuration.

What does actually Doppler monitor?

Doppler is not much feature-rich tool like Netdata. It has a limited set of features and monitors only a handful of things, such as:

• CPU Temperature in Celsius (°C).
  • If the CPU gives multiple temperature recordings, Doppler will display the highest value among all.
• CPU Load in Unit %.
• RAM Usage in MB.
• Swap Usage in MB.
  • If the Swap is not configured in the system, Doppler will simply report 0 (Zero).
• Disk Usage in MB.
• Disk I/O in KB/s.
• Network I/O in KB/s.

It also will display system details, such as;

• Hostname,
• Name of the operating system,
• CPU core count,
• CPU make and model,
• Uptime,
• Process count.

Install Doppler Monitoring Tool In Linux

Download the latest available from the releases page. As of writing this, the latest version was 0.1.0.

$ wget https://github.com/EnKrypt/Doppler/releases/download/v0.1.0/doppler-0.1.0-linux-x64 -O doppler

Move the downloaded file to your $PATH, for example /usr/local/bin/.

$ sudo cp doppler /usr/local/bin/

And, then make it executable using command:

$ sudo chmod +x /usr/local/bin/doppler

Note: Doppler requires lm-sensors to monitor the CPU temperature. If there is no lm-sensors package present on your system, you might encountered with the following error.

Cannot pull temperature data. On Linux, make sure `sensors` is available (package: lm-sensors). For OS X, install osx-temperature-sensor. Some CPUs are not supported on Windows.

To install lm-sensors on your Linux system, refer the following guide.

• How To View CPU Temperature On Linux

Done! It is time to monitor the systems!

Monitor Linux systems using Doppler

Launch Doppler by simply running the following command:

$ doppler

You will see an output like below.

Doppler running on port 3456

As can see, Doppler runs on port 3456 by default.

You might need to allow this port through your firewall or router to access the Doppler web dashboard on remote systems.

On systems that use firewalld, for example RHEL and CentOS, run the following commands one by one to allow the port 3456.

# firewall-cmd --permanent --add-port=3456/udp

# firewall-cmd --permanent --add-port=3456/tcp

Restart firewalld service to take effect the changes.

# firewall-cmd --reload

On systems that use UFW, for example Ubuntu, run:

$ sudo ufw allow 3456

Now, open your web browser and navigate to http://ip-address:3456.

If the port 3456 is already being used, you can simply run Doppler on different port, for example 6543.

$ doppler -p 6543

Now, you can access the Doppler dashboard by navigating to http://ip-address:6543.

Also, Doppler will run with with a polling interval of 2.5 seconds by default. You can, of course, this value as well.

For example, the following command will run Doppler on port 6543 with a polling interval of 5 seconds.

$ doppler -p 6543 -i 5000

Here is the sample screenshots from my CentOS 7 and Ubuntu 18.04 LTS systems.

Monitoring CentOS system using Doppler:

Monitoring Ubuntu system using Doppler:

As you can see, Doppler requires absolutely no configuration! It just works out of the box. You need not to be an advanced Linux user to setup a monitoring tool to your remote or local systems. Just download Doppler, movie it to your path, make it executable and run! It is that simple!!

To get help, run:

$ doppler --help
Options:
  --help          Show help                                            [boolean]
  --version       Show version number                                  [boolean]
  -p, --port      Port to run Doppler on                [number] [default: 3456]
  -i, --interval  How often to poll (in ms)             [number] [default: 2500]

Suggested read:

• Cockpit – Monitor And Administer Linux Servers Via Web Browser
• vnStat – Monitor Network Bandwidth In Linux and BSD
• How To Monitor WiFi Connection From Command Line In Linux
• How To Monitor File Changes Using fswatch In Linux
• How To Quickly Monitor Multiple Hosts In Linux

Uninstalling Doppler

Just remove the Doppler file from the $PATH.

$ sudo rm /usr/local/bin/doppler

If you are a newbie Linux user who don't want to spend much time to setup and configure a remote monitoring tool, Doppler might a good choice. Give it a go and see if it helps.

Resource:

• Doppler GitHub Repository