feat: add ruby server example for level-0

ruby-server-example/Dockerfile

@@ -0,0 +1,15 @@
+# Ruby Alpine image (after using bsf dockerfile digest)
+FROM ruby:3.1-alpine AS build
+# Install all required dependencies for Ruby gems
+RUN apk add --no-cache build-base libxml2-dev libxslt-dev tzdata
+WORKDIR /src
+# Copy the Gemfile and Gemfile.lock into the container
+COPY Gemfile /src/
+# Install the required gems
+RUN bundle install
+# Copy the rest of the application files to the container
+COPY . /src
+# Expose the application port
+EXPOSE 9898
+# Command to run the Ruby application
+CMD ["ruby", "main.rb"]

ruby-server-example/Gemfile

@@ -0,0 +1,3 @@
+source 'https://rubygems.org'
+
+gem 'activesupport', '~> 7.0'

ruby-server-example/main.rb

@@ -0,0 +1,43 @@
+require "socket"
+require "json"
+require "active_support/all"
+
+port = ENV.fetch("PORT", 9898).to_i
+server = TCPServer.new port
+puts "Listening on port #{port}..."
+
+def handle_request(request)
+  method, path, _ = request.split(" ")
+
+  case [method, path]
+  when ["GET", "/ping"]
+    { code: 200, body: "Pong!" }
+  else
+    { code: 404, body: "Not Found" }
+  end
+end
+
+def send_response(client, response)
+  status_line = case response[:code]
+                when 200 then "HTTP/1.1 200 OK\r\n"
+                when 404 then "HTTP/1.1 404 Not Found\r\n"
+                when 400 then "HTTP/1.1 400 Bad Request\r\n"
+                else "HTTP/1.1 500 Internal Server Error\r\n"
+                end
+
+  headers = response[:headers] || { "Content-Type" => "text/html" }
+  headers_section = headers.map { |k, v| "#{k}: #{v}" }.join("\r\n")
+
+  client.write(status_line)
+  client.write(headers_section + "\r\n\r\n")
+  client.write(response[:body]) if response[:body]
+end
+
+loop do
+  Thread.start(server.accept) do |client|
+    request = client.readpartial(2048)
+    response = handle_request(request)
+    send_response(client, response)
+    client.close
+  end
+end