Quickstart Ruby for Resource Graph is not working

[nachtschatt3n]

I tried the Microsoft Quickstart (https://docs.microsoft.com/en-us/azure/governance/resource-graph/first-query-ruby) for Resource Graph and created my bundle file in my Azure Linux CLI /Shell.

Gemfile

# frozen_string_literal: true
source "https://rubygems.org"
git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
gem 'azure_mgmt_resourcegraph'

Then I rand bundle install and unf_ext failed

Using faraday 1.7.0
Fetching unf_ext 0.0.7.7
Installing unf_ext 0.0.7.7 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /home/mathias_uhl/bundle/gems/unf_ext-0.0.7.7/ext/unf_ext
/usr/bin/ruby2.5 -r ./siteconf20210816-419-1knizx7.rb extconf.rb
mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h

extconf failed, exit code 1

Gem files will remain installed in /home/mathias_uhl/bundle/gems/unf_ext-0.0.7.7 for inspection.
Results logged to /home/mathias_uhl/bundle/extensions/x86_64-linux/2.5.0/unf_ext-0.0.7.7/gem_make.out

An error occurred while installing unf_ext (0.0.7.7), and Bundler cannot continue.
Make sure that `gem install unf_ext -v '0.0.7.7' --source 'https://rubygems.org/'` succeeds before bundling.

In Gemfile:
  azure_mgmt_resourcegraph was resolved to 0.17.2, which depends on
    ms_rest_azure was resolved to 0.12.0, which depends on
      faraday-cookie_jar was resolved to 0.0.7, which depends on
        http-cookie was resolved to 1.0.4, which depends on
          domain_name was resolved to 0.5.20190701, which depends on
            unf was resolved to 0.1.4, which depends on
              unf_ext

I seems the ruby-dev package is missing but it seems there is no way to get this installed in the azure web shell?