[add] added docker

Dockerfile

@@ -0,0 +1,69 @@
+ARG RUBY_VERSION=2.7.2
+
+## BUILD ENV
+FROM ruby:${RUBY_VERSION}-alpine AS build_env
+ARG BUILD_PACKAGES="build-base curl-dev git"
+ARG DEV_PACKAGES="sqlite-dev"
+ARG RUBY_PACKAGES="tzdata"
+ARG RAILS_ROOT=/app
+ENV RAILS_ENV=production
+ENV BUNDLE_APP_CONFIG="$RAILS_ROOT/.bundle"
+WORKDIR $RAILS_ROOT
+
+# install packages
+RUN apk update \
+    && apk upgrade \
+    && apk add --update --no-cache $BUILD_PACKAGES $DEV_PACKAGES $RUBY_PACKAGES
+
+# copy app and cleanup dev environment in case this is not a clean git clone
+COPY . .
+RUN rm -rf .bundle vendor .vendor tmp/* db/*.sqlite3 log/* spec
+
+# install gems
+RUN gem install bundler:2.2.9 \
+    && bundle config --global frozen 1 \
+    && bundle config --local path 'vendor/bundle' \
+    && bundle config set without 'development:test:assets' \
+    && bundle install -j4 --retry 3 \
+    # Remove unneeded files (cached *.gem, *.o, *.c)
+    && rm -rf vendor/bundle/ruby/*/cache/*.gem \
+    && find vendor/bundle/ruby/*/gems/ -name "*.c" -delete \
+    && find vendor/bundle/ruby/*/gems/ -name "*.o" -delete
+
+# remove folders not needed in resulting image
+RUN rm -rf tmp/cache app/assets vendor/assets spec docker
+
+## DEPLOY ENV
+FROM ruby:${RUBY_VERSION}-alpine
+ARG PACKAGES="tzdata sqlite-libs"
+ARG RAILS_ROOT=/app
+ENV RAILS_ENV=production
+ENV BUNDLE_APP_CONFIG="$RAILS_ROOT/.bundle"
+ARG USER_UID=12001
+ARG USER_GID=12001
+ARG GROUP_NAME=ryndns
+ARG USER_NAME=ryndns
+WORKDIR $RAILS_ROOT
+
+# make user
+RUN set -eux; \
+    addgroup -g $USER_UID $GROUP_NAME; \
+    adduser -u $USER_UID -G $GROUP_NAME -s /sbin/nologin -D $USER_NAME;
+
+# install packages
+RUN apk update \
+    && apk upgrade \
+    && apk add --update --no-cache $PACKAGES
+
+# get app from build env and add entrypoint
+COPY --from=build_env $RAILS_ROOT $RAILS_ROOT
+COPY ./docker/files/entrypoint.sh /
+
+# create persistent folder and change permission of app
+RUN mkdir -p $RAILS_ROOT/data \
+ && chown -R $USER_NAME:$GROUP_NAME $RAILS_ROOT
+
+USER $USER_NAME
+
+EXPOSE 3000
+ENTRYPOINT ["/entrypoint.sh"]