Running Rails Test Cases in a Docker Container

The Dockerfile that installs the required packages in Alpine.

FROM alpine:3.9

# skip installing gem documentation
RUN mkdir -p /usr/local/etc \
    && { \
        echo 'install: --no-document'; \
        echo 'update: --no-document'; \
    } >> /usr/local/etc/gemrc

ENV RUBY_MAJOR 2.6
ENV RUBY_VERSION 2.6.1
ENV RUBY_DOWNLOAD_SHA256 47b629808e9fd44ce1f760cdf3ed14875fc9b19d4f334e82e2cf25cb2898f2f2

# some of ruby's build scripts are written in ruby
#   we purge system ruby later to make sure our final image uses what we just built
# readline-dev vs libedit-dev: https://bugs.ruby-lang.org/issues/11869 and https://github.com/docker-library/ruby/issues/75
RUN set -ex \
    \
    && apk add --no-cache --virtual .ruby-builddeps \
        autoconf \
        bison \
        bzip2 \
        bzip2-dev \
        ca-certificates \
        coreutils \
        dpkg-dev dpkg \
        gcc \
        gdbm-dev \
        glib-dev \
        libc-dev \
        libffi-dev \
        libxml2-dev \
        libxslt-dev \
        linux-headers \
        make \
        ncurses-dev \
        openssl \
        openssl-dev \
        procps \
        readline-dev \
        ruby \
        tar \
        xz \
        yaml-dev \
        zlib-dev \
    \
    && wget -O ruby.tar.xz "https://cache.ruby-lang.org/pub/ruby/${RUBY_MAJOR%-rc}/ruby-$RUBY_VERSION.tar.xz" \
    && echo "$RUBY_DOWNLOAD_SHA256 *ruby.tar.xz" | sha256sum -c - \
    \
    && mkdir -p /usr/src/ruby \
    && tar -xJf ruby.tar.xz -C /usr/src/ruby --strip-components=1 \
    && rm ruby.tar.xz \
    \
    && cd /usr/src/ruby \
    \
# https://github.com/docker-library/ruby/issues/196
# https://bugs.ruby-lang.org/issues/14387#note-13 (patch source)
# https://bugs.ruby-lang.org/issues/14387#note-16 ("Therefore ncopa's patch looks good for me in general." -- only breaks glibc which doesn't matter here)
    && wget -O 'thread-stack-fix.patch' 'https://bugs.ruby-lang.org/attachments/download/7081/0001-thread_pthread.c-make-get_main_stack-portable-on-lin.patch' \
    && echo '3ab628a51d92fdf0d2b5835e93564857aea73e0c1de00313864a94a6255cb645 *thread-stack-fix.patch' | sha256sum -c - \
    && patch -p1 -i thread-stack-fix.patch \
    && rm thread-stack-fix.patch \
    \
# hack in "ENABLE_PATH_CHECK" disabling to suppress:
#   warning: Insecure world writable dir
    && { \
        echo '#define ENABLE_PATH_CHECK 0'; \
        echo; \
        cat file.c; \
    } > file.c.new \
    && mv file.c.new file.c \
    \
    && autoconf \
    && gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)" \
# the configure script does not detect isnan/isinf as macros
    && export ac_cv_func_isnan=yes ac_cv_func_isinf=yes \
    && ./configure \
        --build="$gnuArch" \
        --disable-install-doc \
        --enable-shared \
    && make -j "$(nproc)" \
    && make install \
    \
    && runDeps="$( \
        scanelf --needed --nobanner --format '%n#p' --recursive /usr/local \
            | tr ',' '\n' \
            | sort -u \
            | awk 'system("[ -e /usr/local/lib/" $1 " ]") == 0 { next } { print "so:" $1 }' \
    )" \
    && apk add --no-network --virtual .ruby-rundeps $runDeps \
        bzip2 \
        ca-certificates \
        libffi-dev \
        procps \
        yaml-dev \
        zlib-dev \
    && apk del --no-network .ruby-builddeps \
    && cd / \
    && rm -r /usr/src/ruby \
# rough smoke test
    && ruby --version && gem --version && bundle --version

# install things globally, for great justice
# and don't create ".bundle" in all our apps
ENV GEM_HOME /usr/local/bundle
ENV BUNDLE_PATH="$GEM_HOME" \
    BUNDLE_SILENCE_ROOT_WARNING=1 \
    BUNDLE_APP_CONFIG="$GEM_HOME"
# path recommendation: https://github.com/bundler/bundler/pull/6469#issuecomment-383235438
ENV PATH $GEM_HOME/bin:$BUNDLE_PATH/gems/bin:$PATH
# adjust permissions of a few directories for running "gem install" as an arbitrary user
RUN mkdir -p "$GEM_HOME" && chmod 777 "$GEM_HOME"
# (BUNDLE_PATH = GEM_HOME, no need to mkdir/chown both)

RUN apk add --no-cache bash
RUN apk add --update ruby-dev build-base \
  libxml2 libxml2-dev libxslt-dev sqlite-dev git

COPY ./test_case.rb /usr/local/bin/
COPY ra.sh /usr/local/bin/

ENTRYPOINT ["ra.sh"]

We copy the script that runs the test case and test case ruby file into the container in /usr/local/bin directory. The test_case.rb:

# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "rails", github: "rails/rails"
  gem "sqlite3"
end

require "active_record"
require "minitest/autorun"
require "logger"

# This connection will do for database-independent bug reports.
ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :owners, force: true do |t|
    t.string :name
    t.timestamps
  end

  create_table :pets, force: true do |t|
    t.references :owner
    t.string :name
    t.timestamps
  end
end

class Owner < ActiveRecord::Base
  has_many :pets, inverse_of: :owner

  def first_pet_name
    pets.first.name
  end
end

class Pet < ActiveRecord::Base
  belongs_to :owner
end

class BugTest < Minitest::Test
  def test_association_scopes_in_block
    owner = Owner.create!(name: 'TestOwner')
    old_pet = Pet.create!(owner: owner, name: 'TestPet')

    assert_equal(owner.first_pet_name, old_pet.name)

    new_pet = owner.pets.where('created_at < ?', 1.year.ago).first_or_create! do |pet|
      pet.name = owner.first_pet_name
    end

    assert_equal(new_pet.name, old_pet.name)
  end
end

This file is taken from an issue from github repo for Rails. The ra.sh bash script:

#!/bin/bash

ruby /usr/local/bin/test_case.rb

The script that builds the Docker image and runs the test case.

#!/bin/bash

echo 'Building docker image'
docker image build -t alpine-rails .
echo 'Running alpine container'
docker container run alpine-rails

We will see the ouput in the standard output.


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