Running Netdata behind H2O

H2O is a new generation HTTP server that provides quicker response to users with less CPU utilization when compared to older generation of web servers.

It is notable for having much simpler configuration than many popular HTTP servers, low resource requirements, and integrated native support for many things that other HTTP servers may need special setup to use.

Why H2O

• Sane configuration defaults mean that typical configurations are very minimalistic and easy to work with.

• Native support for HTTP/2 provides improved performance when accessing the Netdata dashboard remotely.

• Password protect access to the Netdata dashboard without requiring Netdata Cloud.

H2O configuration file

On most systems, the H2O configuration is found under /etc/h2o. H2O uses YAML 1.1, with a few special extensions, for it’s configuration files, with the main configuration file being /etc/h2o/h2o.conf.

You can edit the H2O configuration file with Nano, Vim or any other text editors with which you are comfortable.

After making changes to the configuration files, perform the following:

• Test the configuration with h2o -m test -c /etc/h2o/h2o.conf

• Restart H2O to apply tha changes with /etc/init.d/h2o restart or service h2o restart

Ways to access Netdata via H2O

As a virtual host

With this method instead of SERVER_IP_ADDRESS:19999, the Netdata dashboard can be accessed via a human-readable URL such as netdata.example.com used in the configuration below.

hosts:
  netdata.example.com:
    listen:
      port: 80
    paths:
      /:
        proxy.preserve-host: ON
        proxy.reverse.url: http://127.0.0.1:19999

As a subfolder of an existing virtual host

This method is recommended when Netdata is to be served from a subfolder (or directory). In this case, the virtual host netdata.example.com already exists and Netdata has to be accessed via netdata.example.com/netdata/.

hosts:
  netdata.example.com:
    listen:
      port: 80
    paths:
      /netdata:
        redirect:
          status: 301
          url: /netdata/
      /netdata/:
        proxy.preserve-host: ON
        proxy.reverse.url: http://127.0.0.1:19999

As a subfolder for multiple Netdata servers, via one H2O instance

This is the recommended configuration when one H2O instance will be used to manage multiple Netdata servers via sub-folders.

hosts:
  netdata.example.com:
    listen:
      port: 80
    paths:
      /netdata/server1:
        redirect:
          status: 301
          url: /netdata/server1/
      /netdata/server1/:
        proxy.preserve-host: ON
        proxy.reverse.url: http://198.51.100.1:19999
      /netdata/server2:
        redirect:
          status: 301
          url: /netdata/server2/
      /netdata/server2/:
        proxy.preserve-host: ON
        proxy.reverse.url: http://198.51.100.2:19999

Of course you can add as many backend servers as you like.

Using the above, you access Netdata on the backend servers, like this:

• http://netdata.example.com/netdata/server1/ to reach Netdata on 198.51.100.1:19999
• http://netdata.example.com/netdata/server2/ to reach Netdata on 198.51.100.2:19999

Encrypt the communication between H2O and Netdata

In case Netdata's web server has been configured to use TLS, it is necessary to specify inside the H2O configuration that the final destination is using TLS. To do this, change the http:// on the proxy.reverse.url line in your H2O configuration with https://

Enable authentication

Create an authentication file to enable basic authentication via H2O, this secures your Netdata dashboard.

If you don't have an authentication file, you can use the following command:

printf "yourusername:$(openssl passwd -apr1)" > /etc/h2o/passwords

And then add a basic authentication handler to each path definition:

hosts:
  netdata.example.com:
    listen:
      port: 80
    paths:
      /:
        mruby.handler: |
          require "htpasswd.rb"
          Htpasswd.new("/etc/h2o/passwords", "netdata.example.com")
        proxy.preserve-host: ON
        proxy.reverse.url: http://127.0.0.1:19999

For more information on using basic authentication with H2O, see their official documentation.

Limit direct access to Netdata

If your H2O server is on localhost, you can use this to ensure external access is only possible through H2O:

[web]
    bind to = 127.0.0.1 ::1

You can also use a unix domain socket. This will provide faster communication between H2O and Netdata as well:

[web]
    bind to = unix:/run/netdata/netdata.sock

In the H2O configuration, use a line like the following to connect to Netdata via the unix socket:

proxy.reverse.url http://[unix:/run/netdata/netdata.sock]

If your H2O server is not on localhost, you can set:

[web]
    bind to = *
    allow connections from = IP_OF_H2O_SERVER

note: Netdata v1.9+ support allow connections from

allow connections from accepts Netdata simple patterns to match against the connection IP address.

Prevent the double access.log

H2O logs accesses and Netdata logs them too. You can prevent Netdata from generating its access log, by setting this in /etc/netdata/netdata.conf:

[logs]
    access = off