Be a little more ruby-standard (#762)

This switches the way we fetch dependencies for ruby from `gem` to
`bundler` which is more standard in the ruby world. This is basically a
noop unless you are doing ruby development. But if you *are* doing ruby
development then you can use standard ruby commands like `bundle exec
rspec` locally which makes the project *much* more approachable for ruby
folks. It isn't authoritative though. Jenkins will still use docker, as
will building the docs.

I've not gone so far as to use rake for ruby stuff yet. I'll get there
in a subsequent PR probably.

.bundle/config

@@ -0,0 +1,2 @@
+---
+BUNDLE_PATH: "vendor/bundle"

.dockerignore

@@ -0,0 +1,2 @@
+*
+!Gemfile*

.gitignore

@@ -18,8 +18,7 @@ bin
 !html/sitemap.xml
 metastore_db
 html_docs/
-!resources/asciidoctor/**/bin
-resources/asciidoctor/vendor/**/cache
+vendor
 
 # Comes from running tests in resources/asciidoctor
 resources/asciidoctor/build

Dockerfile

@@ -52,24 +52,6 @@ RUN install_packages \
 # have to be empty. So we delete them.
 RUN rm -rf /var/log/nginx && rm -rf /run
 
-# Gem inventory:
-# * Used by the docs build
-#   * asciidoctor
-#   * thread_safe
-# * Speculative
-#   * asciidoctor-diagram
-#   * asciimath
-# * Used to check the build in CI
-#   * rubocop
-#   * rspec
-RUN gem install --no-document \
-  asciidoctor:1.5.8 \
-  asciidoctor-diagram:1.5.12 \
-  asciimath:1.0.8 \
-  rubocop:0.64.0 \
-  rspec:3.8.0 \
-  thread_safe:0.3.6
-
 # Wheel inventory:
 # * Used to test the docs build
 #   * beautifulsoup4
@@ -79,3 +61,14 @@ RUN pip3 install \
   beautifulsoup4==4.7.1 \
   lxml==4.3.1 \
   pycodestyle==2.5.0
+
+# Install ruby deps with bundler to make things more standard for Ruby folks.
+RUN gem install bundler:2.0.1
+RUN bundle config --global silence_root_warning 1
+COPY Gemfile* /
+RUN bundle install --binstubs --system --frozen
+# --frozen forces us to regenerate Gemfile.lock locally before using it in
+# docker which is important because we need Gemfile.lock to lock the gems to a
+# consistent version and we can't rely on running bundler in docker to update
+# it because we can't copy from the image to the host machine while building
+# the image.

Gemfile

@@ -0,0 +1,18 @@
+# IMPORTANT: If you change this file you should run `bundle lock` to
+# regenerate Gemfile.lock or building the docker image will fail.
+source "https://rubygems.org"
+
+ruby "~> 2.3"
+
+# We commit Gemfile.lock so we're not going to have "unexpected" version bumps
+# of our gems. This file specifies what we think *should* work. Gemfile.lock
+# specifies what we *know* does work.
+gem "asciidoctor", "~> 1.5"          # Used by the docs build
+gem "thread_safe", "~> 0.3.6"        # Used by asciidoctor
+gem "asciidoctor-diagram", "~> 1.5"  # Speculative
+gem "asciimath", "~> 1.0"            # Speculative
+
+group :test do
+  gem "rspec", "~> 3.8"
+  gem "rubocop", "~> 0.64.0"
+end

Gemfile.lock

@@ -0,0 +1,56 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    asciidoctor (1.5.8)
+    asciidoctor-diagram (1.5.12)
+      asciidoctor (~> 1.5.0)
+    asciimath (1.0.8)
+    ast (2.4.0)
+    diff-lcs (1.3)
+    jaro_winkler (1.5.2)
+    parallel (1.16.2)
+    parser (2.6.2.0)
+      ast (~> 2.4.0)
+    powerpack (0.1.2)
+    rainbow (3.0.0)
+    rspec (3.8.0)
+      rspec-core (~> 3.8.0)
+      rspec-expectations (~> 3.8.0)
+      rspec-mocks (~> 3.8.0)
+    rspec-core (3.8.0)
+      rspec-support (~> 3.8.0)
+    rspec-expectations (3.8.2)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.8.0)
+    rspec-mocks (3.8.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.8.0)
+    rspec-support (3.8.0)
+    rubocop (0.64.0)
+      jaro_winkler (~> 1.5.1)
+      parallel (~> 1.10)
+      parser (>= 2.5, != 2.5.1.1)
+      powerpack (~> 0.1)
+      rainbow (>= 2.2.2, < 4.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (~> 1.4.0)
+    ruby-progressbar (1.10.0)
+    thread_safe (0.3.6)
+    unicode-display_width (1.4.1)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  asciidoctor (~> 1.5)
+  asciidoctor-diagram (~> 1.5)
+  asciimath (~> 1.0)
+  rspec (~> 3.8)
+  rubocop (~> 0.64.0)
+  thread_safe (~> 0.3.6)
+
+RUBY VERSION
+   ruby 2.5.3p105
+
+BUNDLED WITH
+   1.17.1

build_docs

@@ -67,7 +67,7 @@ def build_docker_image():
             else:
                 acc.append(line)
 
-        cmd = ["docker", "image", "build", "-t", "elastic/docs_build", "-"]
+        cmd = ["docker", "image", "build", "-t", "elastic/docs_build", DIR]
         build = common_popen(cmd, dockerfile)
         handle_popen(build, handle_line)
         if build.returncode != 0:

resources/asciidoctor/README

@@ -1,3 +1,12 @@
 These are Elastic's extensions to Asciidoctor! The `lib` directory contains
 the actual extensions and the spec directory contains the tests. You can run
-the tests with `build_docs --self-test`.
+the tests with `build_docs --self-test` to reproduce the authoritative, in
+docker tests. You can also use more ruby standard stuff like:
+
+```
+bundle install
+bundle exec rspec
+bundle exec rubocop
+```
+
+but it is not authoritative.