Speed up Docker build

Dockerfile

@@ -1,15 +1,14 @@
-FROM ruby:3-alpine
-RUN apk add --no-cache make gcc libc-dev
-RUN echo -e "#!/bin/sh\ncd /nanoleaf;./main.rb >> /var/log/nanoleaf" > /etc/periodic/15min/nanoleaf
-RUN chmod +x /etc/periodic/15min/nanoleaf
-RUN adduser -DHu 1001 nanoleaf
-RUN touch /var/log/nanoleaf; chown 1001 /var/log/nanoleaf
+FROM alpine
+RUN apk add --no-cache make gcc libc-dev ruby-dev ruby-bundler && \
+    echo -e "#!/bin/sh\ncd /nanoleaf;./main.rb >> /var/log/nanoleaf" > /etc/periodic/15min/nanoleaf && \
+    chmod +x /etc/periodic/15min/nanoleaf && \
+    adduser -DHu 1001 nanoleaf && \
+    touch /var/log/nanoleaf; chown 1001 /var/log/nanoleaf
 WORKDIR /nanoleaf
 RUN chown 1001 .
 USER 1001
 COPY --chown=1001 ["main.rb", "Gemfile", "effect.json", "/nanoleaf/"]
 ENV HOME="/tmp/"
 ENV GEM_HOME="/nanoleaf/vendor/bundle"
-ENV PATH $GEM_HOME/bin:$GEM_HOME/gems/bin:$PATH
-RUN bundle install
+RUN bundle install --jobs=4
 CMD ./main.rb >> /var/log/nanoleaf & tail -F /var/log/nanoleaf

Gemfile

@@ -4,3 +4,4 @@ source 'https://rubygems.org'
 
 gem 'color-converter'
 gem 'oga'
+gem 'json'

main.rb

@@ -1,13 +1,13 @@
 #! /usr/bin/env ruby
 # frozen_string_literal: true
 
-require 'json'
-require 'uri'
-require 'net/http'
 require 'color_converter'
 require 'date'
-require 'open-uri'
+require 'json'
+require 'net/http'
 require 'oga'
+require 'open-uri'
+require 'uri'
 
 def colors
   case Date.today.strftime('%m%d')