Fixed excessive CPU usage

Dockerfile

@@ -1,22 +1,22 @@
 FROM ghcr.io/vshn/asciidoctor-slides:1.17.0
 
-RUN addgroup -S preview && adduser -S preview -G preview
-RUN mkdir -p /presentation && chown -R preview:preview /presentation
-RUN mkdir -p /build && chown -R preview:preview /build
+RUN addgroup -S preview && adduser -S preview -G preview && \
+    mkdir -p /presentation && chown -R preview:preview /presentation && \
+    mkdir -p /build && chown -R preview:preview /build
 
 WORKDIR /build
 
 # The libnotify requirement courtesy of
 # https://github.com/bebraven/platform/pull/82/files
 # to fix file system notification issues when running this image in a Mac
 
-RUN apk update && apk add curl unzip build-base ruby-dev ruby-rdoc libnotify
-RUN gem install guard guard-livereload guard-shell libnotify
-
-RUN curl --silent --location https://github.com/caddyserver/caddy/releases/download/v2.4.6/caddy_2.4.6_linux_amd64.tar.gz -o /build/caddy.tar.gz
-RUN tar -zxvf /build/caddy.tar.gz
-RUN mv /build/caddy /usr/local/bin/caddy
-RUN rm /build/caddy.tar.gz
+RUN apk update && apk add curl unzip build-base ruby-dev ruby-rdoc libnotify && \
+    gem install --no-document guard guard-livereload guard-shell libnotify && \
+    apk del build-base ruby-dev && \
+    curl --silent --location https://github.com/caddyserver/caddy/releases/download/v2.4.6/caddy_2.4.6_linux_amd64.tar.gz -o /build/caddy.tar.gz && \
+    tar -zxvf /build/caddy.tar.gz && \
+    mv /build/caddy /usr/local/bin/caddy && \
+    rm /build/caddy.tar.gz
 
 COPY slides-preview.sh /usr/local/bin/
 COPY signal-listener.sh /usr/local/bin/

Guardfile

@@ -1,7 +1,13 @@
+# Very important!
+ignore %r{^node_modules/}
+
 group :presentation do
     # Rebuild documentation when modifying files
     guard :shell do
-        watch(/slides.adoc/) do
+        watch(/(.*).adoc/) do |a|
+            time = Time.new
+            timestring = time.strftime("%H:%M:%S")
+            puts "#{timestring} - INFO - Got change for: #{a[0]}"
             `generate-vshn-slides --filename=slides.adoc`
         end
     end