Import debian packages and set environment variables for GR.rb

Dockerfile

@@ -1,6 +1,6 @@
 FROM ruby:2.7
 
-ENV BUILD_PACKAGES="apt-utils build-essential curl less nodejs sudo wget zsh libmariadb-dev libserialport-dev cron"
+ENV BUILD_PACKAGES="apt-utils build-essential curl less nodejs sudo wget zsh libmariadb-dev libserialport-dev cron gr"
 
 # throw errors if Gemfile has been modified since Gemfile.lock
 RUN \
@@ -12,10 +12,17 @@ WORKDIR /usr/src/app
 COPY Gemfile Gemfile.lock ./
 
 RUN \
+  echo 'deb http://download.opensuse.org/repositories/science:/gr-framework/Debian_11/ /' | tee /etc/apt/sources.list.d/science:gr-framework.list && \
+  curl -fsSL https://download.opensuse.org/repositories/science:gr-framework/Debian_11/Release.key | gpg --dearmor | tee /etc/apt/trusted.gpg.d/science_gr-framework.gpg > /dev/null && \
   apt-get update -qq && \
   apt-get install -y $BUILD_PACKAGES && \
   bundle install
 
 COPY . .
 
-CMD ["ruby ./smartmeter.rb"]
+# Set required variables for GR.rb
+#  see https://github.com/red-data-tools/GR.rb
+ENV GRDIR="/usr/gr"
+ENV GKS_WSTYPE=100
+
+CMD ["/bin/bash -c ruby ./smartmeter.rb"]