re-added pygments thanx to @z0lberg

alpine/Dockerfile

@@ -1,4 +1,4 @@
-FROM openjdk:13-jdk-alpine
+FROM openjdk:14-jdk-alpine
 
 # see https://github.com/docker-library/openjdk/issues/73
 ENV LC_CTYPE en_US.UTF-8
@@ -8,18 +8,17 @@ RUN addgroup -S dtcgroup && adduser -S dtcuser -G dtcgroup
 RUN apk update && apk add --no-cache build-base
 
 RUN	echo "add needed tools" && \
-    apk add --no-cache curl wget zip unzip git bash \
+    apk add --no-cache curl wget zip unzip git bash --virtual build-dependencies build-base\
     git \
     graphviz \
     python \
-    ruby \
     ruby-dev \
     py-pygments \
     libc6-compat \
     ttf-dejavu 
-RUN gem install --no-ri --no-rdoc  rdoc --no-document 
-#RUN gem install --no-ri --no-rdoc pygments.rb
-RUN apk del ruby-dev
+RUN gem update --system  --no-rdoc --no-ri
+RUN gem install rdoc --no-document 
+RUN gem install pygments.rb
 
 # Add pandoc
 # https://github.com/advancedtelematic/dockerfiles/blob/master/doctools/Dockerfile
@@ -44,6 +43,7 @@ RUN     git clone --branch ng https://github.com/docToolchain/docToolchain.git
         umask g+w && \
         ./gradlew tasks && \
         ./gradlew dependencies && \
+        ./gradlew generatePDF && \
         chmod -R o=u $GRADLE_USER_HOME && \
         chmod -R g=u $GRADLE_USER_HOME && \
         rm -r $GRADLE_USER_HOME/daemon && \