refactor file to take better account of layers.

Author: krystan

containers/javascript-node-lts/.devcontainer/Dockerfile

@@ -5,33 +5,22 @@
 
 FROM node:lts
 
-# Configure apt
 ENV DEBIAN_FRONTEND=noninteractive
-RUN apt-get update \
-    && apt-get -y install --no-install-recommends apt-utils 2>&1
-
-# Verify git and needed tools are installed
-RUN apt-get install -y git procps
+ENV DEBIAN_FRONTEND=dialog
+ENV SHELL /bin/bash
 
-# Remove outdated yarn from /opt and install via package 
-# so it can be easily updated via apt-get upgrade yarn
-RUN rm -rf /opt/yarn-* \
+RUN apt-get update \
+    && apt-get -y install --no-install-recommends apt-utils 2>&1 \
+    && apt-get install -y git procps \
+    && rm -rf /opt/yarn-* \
     && rm -f /usr/local/bin/yarn \
     && rm -f /usr/local/bin/yarnpkg \
     && apt-get install -y curl apt-transport-https lsb-release \
     && curl -sS https://dl.yarnpkg.com/$(lsb_release -is | tr '[:upper:]' '[:lower:]')/pubkey.gpg | apt-key add - 2>/dev/null \
     && echo "deb https://dl.yarnpkg.com/$(lsb_release -is | tr '[:upper:]' '[:lower:]')/ stable main" | tee /etc/apt/sources.list.d/yarn.list \
     && apt-get update \
-    && apt-get -y install --no-install-recommends yarn
-    
-# Install eslint
-RUN npm install -g eslint
-
-# Clean up
-RUN apt-get autoremove -y \
+    && apt-get -y install --no-install-recommends yarn \
+    && npm install -g eslint \
+    && apt-get autoremove -y \
     && apt-get clean -y \
-    && rm -rf /var/lib/apt/lists/*
-ENV DEBIAN_FRONTEND=dialog
-
-# Set the default shell to bash instead of sh
-ENV SHELL /bin/bash
+    && rm -rf /var/lib/apt/lists/* \

containers/typescript-node-8/.devcontainer/Dockerfile

@@ -7,31 +7,21 @@ FROM node:8
 
 # Configure apt
 ENV DEBIAN_FRONTEND=noninteractive
-RUN apt-get update \
-    && apt-get -y install --no-install-recommends apt-utils 2>&1
-
-# Verify git and needed tools are installed
-RUN apt-get install -y git procps
+ENV DEBIAN_FRONTEND=dialog
+ENV SHELL /bin/bash
 
-# Remove outdated yarn from /opt and install via package 
-# so it can be easily updated via apt-get upgrade yarn
-RUN rm -rf /opt/yarn-* \
+RUN apt-get update \
+    && apt-get -y install --no-install-recommends apt-utils 2>&1 \
+    && apt-get install -y git procps \
+    && rm -rf /opt/yarn-* \
     && rm -f /usr/local/bin/yarn \
     && rm -f /usr/local/bin/yarnpkg \
     && apt-get install -y curl apt-transport-https lsb-release \
     && curl -sS https://dl.yarnpkg.com/$(lsb_release -is | tr '[:upper:]' '[:lower:]')/pubkey.gpg | apt-key add - 2>/dev/null \
     && echo "deb https://dl.yarnpkg.com/$(lsb_release -is | tr '[:upper:]' '[:lower:]')/ stable main" | tee /etc/apt/sources.list.d/yarn.list \
     && apt-get update \
-    && apt-get -y install --no-install-recommends yarn
-
-# Install tslint and typescript
-RUN npm install -g tslint typescript
-
-# Clean up
-RUN apt-get autoremove -y \
+    && apt-get -y install --no-install-recommends yarn \
+    && npm install -g tslint typescript \
+    && apt-get autoremove -y \
     && apt-get clean -y \
-    && rm -rf /var/lib/apt/lists/*
-ENV DEBIAN_FRONTEND=dialog
-
-# Set the default shell to bash instead of sh
-ENV SHELL /bin/bash
+    && rm -rf /var/lib/apt/lists/*