Netdata is a daemon that collects system information from a linux system and presents a web site to view the data. The presentation is full of charts that precisely render all system values, in realtime, for a short time (1 hour by default).

You can use it to monitor all your servers, linux PCs or linux embedded devices, without the need to ssh to them. Also, you can view a short history of all collected values, so if something happens you can use netdata to find out what and when.

Check it live at:

• My Home Gentoo Box
• My Home Raspberry Pi B+ with data collection every 5s (raspbian playing movies 24x7)
• My Home Raspberry Pi 2 (osmc as an access point)

Here is a screenshot:

• highly optimized C code

  It only needs a few milliseconds per second to collect all the data. It will nicelly run even on a raspberry pi with just one cpu core, or any other embedded system.

• extremely lightweight

  It only needs a few megabytes of memory to store all its round robin database.

  Although netdata does all its calculation using long double (128 bit) arithmetics, it stores all values using a custom-made 32-bit number. This custom-made number can store in 29 bits values from -167772150000000.0 to 167772150000000.0 with a precision of 0.00001 (yes, it is a floating point number, meaning that higher integer values have less decimal precision) and 3 bits for flags (2 are currently used and 1 is reserved for future use). This provides an extremely optimized memory footprint with just 0.0001% max accuracy loss (run: ./netdata --unittest to see it in action).

• per second data collection

  Every chart, every value, is updated every second. Of course, you can control collection period per module.

  netdata can perform several calculations on each value (dimension) collected:

  • absolute, stores the collected value, as collected (this is used, for example for the number of processes running, the number of connections open, the amount of RAM used, etc)

  • incremental, stores the difference of the collected value to the last collected value (this is used, for example, for the bandwidth of interfaces, disk I/O, i.e. for counters that always get incremented) - netdata automatically interpolates these values to second boundary, using nanosecond calculations so that small delays at the data collection layer will not affect the quality of the result - also, netdata detects arithmetic overflows and presents them properly at the charts.

  • percentage of absolute row, stores the percentage of the collected value, over the sum of all dimensions of the chart.

  • percentage of incremental row, stores the percentage of this collected value, over the sum of the the incremental differences of all dimensions of the chart (this is used, for example, for system CPU utilization).

• visualizes QoS classes automatically

  If you also use FireQOS for QoS, it collects class names automatically.

• appealing web site

  The web site uses bootstrap and google charts for a very appealing result. It works even on mobile devices and adapts to screen size changes and rotation (responsive design).

• web charts do respect your browser resources

  The charts adapt to show only as many points are required to have a clear view. Also, the javascript code respects your browser resources (stops refreshing when the window looses focus, when scrolling, etc).

• highly configurable

  All charts and all features can be enabled or disabled. The program generates its configuration file based on the resources available on the system it runs, for you to edit.

• It reads and renders charts for all these:

• /proc/net/dev (all netwrok interfaces for all their values)

• /proc/diskstats (all disks for all their values)

• /proc/net/snmp (total IPv4, TCP and UDP usage)

• /proc/net/netstat (more IPv4 usage)

• /proc/net/stat/nf_conntrack (connection tracking performance)

• /proc/net/ip_vs/stats (IPVS connection statistics)

• /proc/stat (CPU utilization)

• /proc/meminfo (memory information)

• /proc/vmstat (system performance)

• /proc/net/rpc/nfsd (NFS server statistics for both v3 and v4 NFS)

• tc classes (QoS classes)

• It supports plugins for collecting information from other sources!

  Plugins can be written in any computer language (pipe / stdout communication for data collection).

  It ships with 2 plugins: apps.plugin and charts.d.plugin:

• apps.plugin is a plugin that attempts to collect statistics per process. It groups the entire process tree based on your settings (for example, mplayer, kodi, vlc are all considered media) and for each group it attempts to find CPU usage, memory usages, physical and logical disk read and writes, number of processes, number of threads, number of open files, number of open sockets, number of open pipes, minor and major page faults (major = swapping), etc. 15 stackable (per group) charts in total.

• charts.d.plugin provides a simple way to script data collection in BASH. It includes example plugins that collect values from:

  • nut (UPS load, frequency, voltage, etc)
  • sensors (temperature, voltage, current, power, humidity, fans rotation sensors)
  • cpufreq (current CPU clock frequency)
  • postfix (e-mail queue size)
  • squid (web proxy statistics)
  • mysql (mysql global statistics)

  Of course, you can write your own using BASH scripting.

• netdata is a web server, supporting gzip compression

  It serves its own static files and dynamic files for rendering the site. It does not support authentication or SSL - limit its access using your firewall. It does not allow .. or / in the files requested (so it can only serve files stored in the web/ directory).

1. You run a daemon on your linux: netdata. This deamon is written in C and is extremely lightweight.

netdata:

• Spawns threads to collect all the data for all sources
• Keeps track of the collected values in memory (no disk I/O at all)
• Generates JSON and JSONP HTTP responses containing all the data needed for the web graphs
• Is a standalone web server.

For example, you can access JSON data by using:

http://127.0.0.1:19999/data/net.eth0

This will give you the JSON file for traffic on eth0. The above is equivalent to:

http://127.0.0.1:19999/data/net.eth0/3600/1/average/0/0

where:

• 3600 is the number of entries to generate.
• 1 is grouping count, 1 = every single entry, 2 = half the entries, 3 = one every 3 entries, etc
• average is the grouping method. It can also be max.
• 0/0 they are before and after timestamps, allowing panning on the data

2. If you need to embed a netdata chart on your web page, you can add a few javascript lines and a div for every graph you need. Check this example (open it in a new tab and view its source to get the idea).

3. Graphs are generated using Google Charts API (so, your client needs to have internet access).

Before you start, make sure you have zlib development files installed. To install it in Ubuntu, you need to run:

apt-get install zlib1g-dev

Then do this to install and run netdata:

git clone https://github.com/ktsaou/netdata.git netdata.git
cd netdata.git
./netdata.start

Once you run it, the file conf.d/netdata.conf will be created. You can edit this file to set options for each graph. To apply the changes you made, you have to run netdata.start again.

If you run netdata.start as root, netdata will start by default as nobody. Otherwise it will run as the user that started it. If you run it as root, you can set the user you want it to run in the config file conf.d/netdata.conf.

To access the web site for all graphs, go to:

http://127.0.0.1:19999/

You can get the running config file at any time, by accessing http://127.0.0.1:19999/netdata.conf.

To start it at boot, just run /path/to/netdata.git/netdata.start from your /etc/rc.local or equivalent.

You can stop and start netdata at any point. Netdata saves on exit its round robbin database to cache/ so that it will continue from where it stopped the last time.