Add docker for website generation

.gitignore

@@ -93,3 +93,5 @@ compiler/test-coursier/run/*.jar
 # docs related
 contributors.js
 content-contributors.css
+docs/_spec/_site/
+docs/_spec/.jekyll-metadata

docs/_spec/Dockerfile

@@ -0,0 +1,24 @@
+FROM ruby:2.7
+
+RUN apt-get install -y curl \
+  && curl -sL https://deb.nodesource.com/setup_18.x | bash - \
+  && apt-get install -y nodejs \
+  && curl -L https://www.npmjs.com/install.sh | sh
+
+RUN gem install  bundler:1.17.2 jekyll 
+
+WORKDIR /srv/jekyll
+
+COPY Gemfile .
+COPY Gemfile.lock .
+
+
+RUN echo -n "bundle version: " && bundle --version
+RUN bundle install
+RUN mkdir /opt/npm-global
+RUN npm config set prefix '/opt/npm-global'
+RUN npm config set global true
+RUN npm install  bower
+RUN echo -n "npm version: " && npm --version
+RUN chmod u+s /bin/chown
+RUN date

docs/_spec/Gemfile

@@ -0,0 +1,8 @@
+# To build the spec on Travis CI
+source "https://rubygems.org"
+
+gem "jekyll", "3.6.3"
+gem "webrick"
+gem "rouge"
+# gem 's3_website'
+gem "redcarpet", "3.5.1"

docs/_spec/Gemfile.lock

@@ -0,0 +1,57 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    addressable (2.8.1)
+      public_suffix (>= 2.0.2, < 6.0)
+    colorator (1.1.0)
+    ffi (1.15.5)
+    forwardable-extended (2.6.0)
+    jekyll (3.6.3)
+      addressable (~> 2.4)
+      colorator (~> 1.0)
+      jekyll-sass-converter (~> 1.0)
+      jekyll-watch (~> 1.1)
+      kramdown (~> 1.14)
+      liquid (~> 4.0)
+      mercenary (~> 0.3.3)
+      pathutil (~> 0.9)
+      rouge (>= 1.7, < 3)
+      safe_yaml (~> 1.0)
+    jekyll-sass-converter (1.5.2)
+      sass (~> 3.4)
+    jekyll-watch (1.5.1)
+      listen (~> 3.0)
+    kramdown (1.17.0)
+    liquid (4.0.3)
+    listen (3.7.1)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
+    mercenary (0.3.6)
+    pathutil (0.16.2)
+      forwardable-extended (~> 2.6)
+    public_suffix (5.0.0)
+    rb-fsevent (0.11.2)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
+    redcarpet (3.5.1)
+    rouge (2.2.1)
+    safe_yaml (1.0.5)
+    sass (3.7.4)
+      sass-listen (~> 4.0.0)
+    sass-listen (4.0.0)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
+    webrick (1.7.0)
+
+PLATFORMS
+  ruby
+  x86_64-linux
+
+DEPENDENCIES
+  jekyll (= 3.6.3)
+  redcarpet (= 3.5.1)
+  rouge
+  webrick
+
+BUNDLED WITH
+   2.3.5

docs/_spec/README.md

@@ -16,11 +16,22 @@ We aim to track the configuration GitHub Pages uses but differences may arise as
 
 ## Building
 
+<!-- TODO: change url to correct one -->
 Travis CI builds the spec automatically after every merged pull release and publishes to https://www.scala-lang.org/files/archive/spec/2.13/.
 
+<!-- TODO: Check nothing else is needed -->
+To preview locally, run the following commands in the docs/_spec subfolder:
+
+```
+env UID="$(id -u)" GID="$(id -g)" docker-compose up
+```
+
+and open http://0.0.0.0:4000/files/archive/spec/2.13/ to view the spec. Jekyll will rebuild as you edit the markdown, but make sure to restart it when you change `_config.yml`.
+<!-- 
 To preview locally, run the following commands in the root of your checkout scala/scala:
 `bundle install` to install Jekyll and `bundle exec jekyll serve -d build/spec/ -s spec/ -w --baseurl=""` to start it,
 and open http://0.0.0.0:4000/ to view the spec. Jekyll will rebuild as you edit the markdown, but make sure to restart it when you change `_config.yml`.
+-->
 
 ## General Advice for editors
 

docs/_spec/docker-compose.yml

@@ -0,0 +1,11 @@
+version: '2'
+
+services:
+  jekyll:
+    user: "${UID}:${GID}"
+    build: .
+    command: sh -c "chown $UID / &&   bundle exec jekyll serve --incremental --host=0.0.0.0 "
+    ports:
+      - '4000:4000'
+    volumes:
+      - .:/srv/jekyll