Rails: Find if server has libvips or other package installed

Question

I'm moving my application files to an ActiveStorage solution and would like to take advantage of its image interpolation functions (resize, crop, etc).

I have about 100+ application instances that stands on about 30 servers. Not all have the libvips or the imagemagick package installed, so I would like to add the variant method only if that lib is present. For example something like:

if has_my_server_libvips? 
  logo_header = Portal.logo_header.variant({ resize_to_fit: [230, 50] })
else
  logo_header = Portal.logo_header
end

Is there any Ruby / RoR built-in / custom method to check it?

Answer 1

You can check if these libraries have executable command. This is just idea, you can implement it as you wish

logo_header =
  if %i[vips magick].any? { |command| `which #{command}`.present? } 
    Portal.logo_header.variant({ resize_to_fit: [230, 50] })
  else
    Portal.logo_header
  end

which command returns path of executable bin (with new line character in the end) or empty string if absent

---

You can also define such method (for example in Kernel)

module Kernel
  def command_exists?(command)
    command = command.delete('^a-zA-Z')

    !`which #{command}`.empty?
  end
end

But be careful: sanitize argument before call this method to prevent injection!