Fix Ruby quickstart container startup

quickstarts/languages/ruby/Dockerfile

@@ -1,14 +1,18 @@
 # Use the official lightweight Ruby image.
 # https://hub.docker.com/_/ruby
 FROM ruby:3.3-slim
+ENV RACK_ENV=production
 
 # Install production dependencies.
 WORKDIR /usr/src/app
-COPY Gemfile ./
-RUN bundle install
+COPY Gemfile Gemfile.lock ./
+RUN apt-get update && apt-get install -y --no-install-recommends build-essential \
+    && bundle install \
+    && apt-get purge -y --auto-remove build-essential \
+    && rm -rf /var/lib/apt/lists/*
 
 # Copy local code to the container image.
 COPY . ./
 
 # Run the web service on container startup.
-CMD ["ruby", "./app.rb"]
+CMD ["bundle", "exec", "ruby", "./app.rb"]

quickstarts/languages/ruby/Gemfile

@@ -2,3 +2,5 @@ source 'https://rubygems.org'
 
 gem 'sinatra'
 gem 'rack', '>= 2.0.6'
+gem 'rackup'
+gem 'puma'

quickstarts/languages/ruby/Gemfile.lock

@@ -0,0 +1,41 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    base64 (0.3.0)
+    logger (1.7.0)
+    mustermann (3.1.1)
+    nio4r (2.7.5)
+    puma (8.0.2)
+      nio4r (~> 2.0)
+    rack (3.2.6)
+    rack-protection (4.2.1)
+      base64 (>= 0.1.0)
+      logger (>= 1.6.0)
+      rack (>= 3.0.0, < 4)
+    rack-session (2.1.2)
+      base64 (>= 0.1.0)
+      rack (>= 3.0.0)
+    rackup (2.3.1)
+      rack (>= 3)
+    sinatra (4.2.1)
+      logger (>= 1.6.0)
+      mustermann (~> 3.0)
+      rack (>= 3.0.0, < 4)
+      rack-protection (= 4.2.1)
+      rack-session (>= 2.0.0, < 3)
+      tilt (~> 2.0)
+    tilt (2.7.0)
+
+PLATFORMS
+  aarch64-linux
+  ruby
+  x86_64-linux
+
+DEPENDENCIES
+  puma
+  rack (>= 2.0.6)
+  rackup
+  sinatra
+
+BUNDLED WITH
+   2.5.22