Improve the docker image build

* update alpine to 3.12 and drop the patch version
* use "Installing for" instead of "Selecting to" for packages
* use --update flag of apk
* remove clean cache command as it's already empty with --no-cache flag
* align nikto user creation message with the group
* remove the root password locking stuff: irrelevant with alpine 3.12
* add a .dockerignore file to send less context to the daemon
* bring the image size down from 47.2MB to 45.7MB

Author: NicolasCARPi

.dockerignore

@@ -0,0 +1,9 @@
+.git
+.gitignore
+.gitattributes
+.editorconfig
+.github
+COPYING
+devdocs
+documentation
+README.md

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.10.0
+FROM alpine:3.12
 
 LABEL version="2.1.6" \
       author="Author Paul Sec (https://github.com/PaulSec), Nikto User https://github.com/drwetter" \
@@ -10,25 +10,16 @@ COPY ["program/", "/nikto"]
 
 ENV  PATH=${PATH}:/nikto
 
-RUN echo 'Selecting packages to Nikto.' \
-  && apk update \
-  && apk add --no-cache --virtual .build-deps \
+RUN echo 'Installing packages for Nikto.' \
+  && apk add --update --no-cache --virtual .build-deps \
      perl \
      perl-net-ssleay \
-  && echo 'Cleaning cache from APK.' \
-  && rm -rf /var/cache/apk/* \
   && echo 'Creating the nikto group.' \
   && addgroup nikto \
-  && echo 'Creating the user nikto.' \
+  && echo 'Creating the nikto user.' \
   && adduser -G nikto -g "Nikto user" -s /bin/sh -D nikto \
   && echo 'Changing the ownership.' \
   && chown -R nikto.nikto /nikto \
-  && echo 'Creating a random password for root.' \
-  && export RANDOM_PASSWORD=`tr -dc A-Za-z0-9 < /dev/urandom | head -c44` \
-  && echo "root:$RANDOM_PASSWORD" | chpasswd \
-  && unset RANDOM_PASSWORD \
-  && echo 'Locking root account.' \
-  && passwd -l root \
   && echo 'Finishing image.'
 
 USER nikto