Build a better docker container

.dockerignore

@@ -10,11 +10,14 @@
 /.simplecov
 /.spellr.yml
 /.travis.yml
+/Gemfile.lock
 /Dockerfile
 /Rakefile
 /vendor/
 /.bundle/
 /.github
-/spec
-/bin
-/.spellr_wordlists
+/pkg
+/tmp
+/coverage
+/.ruby-version
+/.rspec_status

.github/workflows/ci.yml

@@ -74,3 +74,9 @@ jobs:
         bundler-cache: true
     - run: bundle exec rake build
 
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - run: bin/docker_build
+

.spellr_wordlists/shell.txt

@@ -1,3 +1,5 @@
 apk
 euo
+grep
 musl
+xeuo

Dockerfile

@@ -1,8 +1,12 @@
 FROM ruby:alpine
 WORKDIR /spellr
-COPY . .
+COPY Gemfile spellr.gemspec .
+COPY ./lib/spellr/version.rb ./lib/spellr/
 RUN apk add --no-cache make musl-dev gcc && \
-  gem install bundler && \
-  bundle install --without=development
+  BUNDLE_WITHOUT=development bundle install
+
+FROM ruby:alpine
+COPY . /spellr
+COPY --from=0 /usr/local/bundle /usr/local/bundle
 WORKDIR /app
 ENTRYPOINT ["/spellr/exe/spellr"]

Rakefile

@@ -17,7 +17,7 @@ task default: [:spec, :rubocop, :spellr, :leftovers, :build]
 
 namespace :release do
   task :dockerhub_push do
-    system("#{__dir__}/bin/dockerhub_push")
+    system('bin/dockerhub_push', chdir: __dir__)
   end
 end
 Rake::Task[:release].enhance([:"release:dockerhub_push"])

bin/docker_build

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+version_tag=${1-"v$(grep -F VERSION lib/spellr/version.rb | cut -d"'" -f2)"}
+if (( ${#version_tag} < 7 )); then
+  echo "version '$version_tag' doesn't look correct"
+  exit 1
+fi
+
+docker build -t robotdana/spellr:$version_tag -t robotdana/spellr:latest .
+
+# prove it works
+[[ v$(docker run -it -v $PWD:/app robotdana/spellr:$version_tag --version | tr -d '\r') == $version_tag ]]

bin/dockerhub_push

@@ -1,12 +1,9 @@
 #!/usr/bin/env bash
 
-set -euo pipefail
+set -xeuo pipefail
 
 version_tag=$(git describe --exact-match --abbrev=0)
-
-docker build -t robotdana/spellr:$version_tag -t robotdana/spellr:latest .
-# prove it works
-docker run -it -v $PWD:/app robotdana/spellr:$version_tag --version
+. ./bin/docker_build $version_tag
 
 docker push robotdana/spellr:$version_tag
 docker push robotdana/spellr:latest