Deploy using Dockerfile instead of buildpack

Based on https://github.com/rails/rails/blob/4f0f3448cde85ff3d1485366231650258ea62b71/railties/lib/rails/generators/rails/app/templates/Dockerfile.tt

Deploy failing after heroku/heroku-buildpack-ruby#1428

.github/workflows/test.yml

@@ -14,4 +14,5 @@ jobs:
     - uses: ruby/setup-ruby@v1
       with:
         bundler-cache: true
-    - run: bin/test
+    - run: |
+        docker run --rm -it --env PORT=8080 $(docker build . -q) bin/test

Dockerfile

@@ -0,0 +1,57 @@
+# Make sure RUBY_VERSION matches the Ruby version in .ruby-version
+ARG RUBY_VERSION=3.2.3
+FROM registry.docker.com/library/ruby:$RUBY_VERSION-slim as base
+
+# The app lives here
+WORKDIR /app
+
+# Install base packages
+RUN apt-get update -qq && \
+    apt-get install --no-install-recommends -y \
+    curl
+
+# Set production environment
+ENV BUNDLE_DEPLOYMENT="1" \
+    BUNDLE_PATH="/usr/local/bundle" \
+    BUNDLE_WITHOUT="development"
+
+# Throw-away build stage to reduce size of final image
+FROM base as build
+
+# Install build packages
+RUN apt-get install --no-install-recommends -y \
+    build-essential \
+    git \
+    pkg-config
+
+# Install application gems
+COPY Gemfile Gemfile.lock .ruby-version ./
+RUN bundle install
+
+# Copy application code
+COPY . .
+
+# Final stage for app image
+FROM base
+
+ARG APPUSER=app
+ARG APPDIR=/app
+
+# Clean up installation packages to reduce image size
+RUN rm -rf /var/lib/apt/lists /var/cache/apt/archives
+
+# Copy built artifacts: gems, application
+COPY --from=build "${BUNDLE_PATH}" "${BUNDLE_PATH}"
+COPY --from=build $APPDIR $APPDIR
+
+# Run and own only the runtime files as a non-root user for security
+RUN mkdir -p log tmp
+RUN groupadd --system --gid 1000 $APPUSER
+RUN useradd $APPUSER --uid 1000 --gid 1000 --create-home --shell /bin/bash
+RUN chown -R $APPUSER:$APPUSER log tmp
+USER 1000:1000
+
+RUN gem install overman
+
+# Start the server by default, this can be overwritten at runtime
+CMD ["overman", "start"]

README.md

@@ -6,15 +6,26 @@ Returns a list of URLs.
 
 Start
 
-    foreman start
+```bash
+overman start
+
+# in docker
+bin/docker-run
+```
 
 Test
 
-    bin/test
+```bash
+bin/test
 
+# in docker
+docker run --rm -it -e PORT=8080 $(docker build . -q) bin/test
+```
 ## Deploy
 
-    git push # to github
+```bash
+git push # to github
+```
 
 ## Example usage
 

bin/docker-run

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+TAG=${TAG:-urls}
+PORT=${PORT:-8080}
+
+# echo commands
+set -x
+
+docker build . -t $TAG
+docker run --rm -it --publish ${PORT}:${PORT} --env PORT=${PORT} $TAG

bin/test

@@ -3,6 +3,7 @@
 # echo commands
 set -x
 
+PORT=${PORT:-8080}
 RUBYOPT=-W:deprecated
 
 # info
@@ -12,22 +13,22 @@ gem -v
 
 # install app dependencies
 bundle install
-which foreman || gem install --no-document foreman
+which overman || gem install --no-document overman
 
 # start app and wait for it
-foreman start &
+overman start &
 sleep 3
 
 # run tests and save the result
 
 # tests Urls.by_url
 # can't use "localhost" because that's a NullURL in twingly/url
-curl --silent --fail "http://localhost:5000/?url=localhost.v4.dentarg.net:5000" | grep -q "3 URLs for"
+curl --silent --fail "http://localhost:${PORT}/?url=localhost.v4.dentarg.net:${PORT}" | grep -q "3 URLs for"
 test1=$?
 
 # tests Urls.by_text
 curl --silent --fail --data \
- 'text=http://www.example.org https://google.com blog.trello.com' "http://localhost:5000/text" | grep -q "3 URLs"
+ 'text=http://www.example.org https://google.com blog.trello.com' "http://localhost:${PORT}/text" | grep -q "3 URLs"
 test2=$?
 
 # stop app

fly.toml

@@ -1,8 +1,5 @@
 app = "urls"
 
-[build]
-  builder = "heroku/buildpacks:20"
-
 [env]
   PORT = "8080"
   RACK_ENV = "production"