[dist] Adapt binary names to ruby2.5

Since we are not using the ruby version defined by the base system, but
the one OBS uses, we have to adjust the call of the binaries that were
installed via gem command.

Dockerfile

@@ -18,9 +18,15 @@ RUN chown -R frontend /obs/src/api
 USER frontend
 WORKDIR /obs/src/api
 
+# foreman, which we only run in docker, needs a different thor version than OBS.
+# Installing the gem directly spares us from having to rpm package two different thor versions.
+RUN sudo gem.ruby2.5 install thor:0.19 foreman
+# Ensure there is a foreman command without ruby suffix
+RUN sudo ln -s /usr/bin/foreman.ruby2.5 /usr/bin/foreman
+
 # FIXME: Retrying bundler if it fails is a workaround for https://github.com/moby/moby/issues/783
 #        which seems to happen on openSUSE (< Tumbleweed 20171001)...
 RUN export NOKOGIRI_USE_SYSTEM_LIBRARIES=1; bundle install --jobs=3 --retry=3 || bundle install --jobs=3 --retry=3
 
 # Run our command
-CMD ["foreman", "start", "-f", "Procfile"] 
+CMD ["foreman", "start", "-f", "Procfile"]

Dockerfile.frontend-base

@@ -17,7 +17,7 @@ RUN chown -R frontend /obs/src/api
 USER frontend
 WORKDIR /obs/src/api
 
-# Set up some convenience ruby binaries...
+# Ensure there are ruby, gem and irb commands without ruby suffix
 RUN for i in ruby gem irb; do ln -s /usr/bin/$i.ruby2.5 ~/bin/$i; done
 
 # Install our bundle