Update Docker setup

Dockerfile

@@ -1,5 +1,5 @@
-FROM ruby:2.5.1
-RUN curl -sL https://deb.nodesource.com/setup_10.x | bash -
+FROM ruby:2.7.1
+RUN curl -sL https://deb.nodesource.com/setup_12.x | bash -
 RUN curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add -
 RUN echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list
 RUN apt-get update -qq && apt-get install -qq --no-install-recommends \

Makefile

@@ -9,14 +9,11 @@ help:
 	@echo
 
 # Builds intermediate files. Needs a _site built first though
-update: _site critical
+update: _site
 
 # Builds _site
 _site:
-	bundle exec jekyll build --incremental
-
-critical: _site ## Builds critical path CSS/JS
-	yarn critical
+	yarn build
 
 dev: 
 	yarn dev

docker-compose.yml

@@ -6,11 +6,14 @@ services:
       - .:/app
       - rubygems:/usr/local/bundle
       - ./node_modules:/app/node_modules
+      - yarn_cache:/root/.cache/yarn
     ports:
       - '4001:4001'
       - '35729:35729'
-    command: 'env PORT=4001 HOST=0.0.0.0 yarn run dev'
+    command: >
+      bash -c 'yarn; bundle; env PORT=4001 HOST=0.0.0.0 yarn run dev'
 
 volumes:
   rubygems:
   node_modules:
+  yarn_cache: