I want to add a custom button with custom command, to host show view. For example, to be able to restart the host by using custom command (which would take host ip as argument). Do you know where to begin to look at?
I would use a custom navigation to create a host action. This can be found at “your user name” > “My Account” > “Custom Navigation”. You can use placeholders like
$host.address$ in the URL there.
If you have to write the webservice to handle it, then I would start with a custom module where https://github.com/icinga/icingaweb2-module-training is a good start until there is some more documentation.