From 99c0e7adf20e7b75277c419cc40f0d83a6328eb1 Mon Sep 17 00:00:00 2001
From: "R. Tyler Croy" <tyler@monkeypox.org>
Date: Tue, 20 Feb 2018 14:08:26 -0800
Subject: [PATCH] Multi-stage builds, wheee

---
 Dockerfile | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index 5243c94..850cb2a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,26 +1,38 @@
-FROM ruby:2.3-alpine
+FROM ruby:2.3-alpine as builder
 
-ARG BUILD_PKGS="ruby-dev openssl-dev gcc make libc-dev binutils"
 ARG APP_DIR=/webapp
-
-RUN mkdir -p ${APP_DIR}/vendor
-
-WORKDIR ${APP_DIR}
+ARG BUILD_PKGS="ruby-dev openssl-dev gcc make libc-dev binutils"
 
 ENV GEM_HOME=${APP_DIR}/vendor/gems
 ENV BUNDLE_PATH=${APP_DIR}/vendor/gems
 ENV BUNDLE_APP_CONFIG=${APP_DIR}/vendor/gems/.bundle
 ENV BUNDLE_DISABLE_SHARED_GEMS=true
 
+RUN mkdir -p ${APP_DIR}/vendor
+
+WORKDIR ${APP_DIR}
 ADD Gemfile* ${APP_DIR}/
+RUN apk add -U ${BUILD_PKGS} && \
+        bundle install && \
+        apk del ${BUILD_PKGS} && \
+        rm -rf /var/cache/apk/*
+
+# Doing a multi-stage build to reset some stuff for a smaller image
+FROM ruby:2.3-alpine
+
+ARG APP_DIR=/webapp
+WORKDIR ${APP_DIR}
+
+COPY --from=builder ${APP_DIR} .
+
+ENV GEM_HOME=${APP_DIR}/vendor/gems
+ENV BUNDLE_PATH=${APP_DIR}/vendor/gems
+ENV BUNDLE_APP_CONFIG=${APP_DIR}/vendor/gems/.bundle
+ENV BUNDLE_DISABLE_SHARED_GEMS=true
+
 ADD app/ ${APP_DIR}/app/
 ADD config.ru ${APP_DIR}/
 ADD views ${APP_DIR}/views/
 ADD assets ${APP_DIR}/assets/
 
-RUN apk add -U ${BUILD_PKGS} && \
-        bundle install --without test && \
-        apk del ${BUILD_PKGS} && \
-        rm -rf /var/cache/apk/*
-
 CMD bundle exec puma