improve docker build

src/Dockerfile

@@ -1,46 +1,73 @@
-FROM kasmweb/core-ubuntu-bionic:1.10.0
-USER root
+######### Config Arguments ###########
+ARG NERD_FONTS_ARCHIVE="Hack.zip"
+ARG NERD_FONTS_VERSION="v2.1.0"
 
-ENV HOME /home/kasm-default-profile
-ENV STARTUPDIR /dockerstartup
-ENV INST_SCRIPTS $STARTUPDIR/install
-WORKDIR $HOME
 
+######### Temporary Files Layer ###########
+FROM busybox:1.36.1-glibc AS temp-files
 
-######### Customize Container Here ###########
+# Make config arguments from above known in this layer
+ARG NERD_FONTS_ARCHIVE
+ARG NERD_FONTS_VERSION
 
-RUN apt update
-RUN apt -y upgrade
-RUN apt -y install openvpn
-RUN apt -y install unzip
+# Local files
+COPY assets/mr-robot-wallpaper.png  /copy/configs/usr/share/extra/backgrounds/bg_default.png
+COPY config/starship.toml /copy/configs/root/.config/starship.toml
+COPY config/terminator.toml /copy/configs/root/.config/terminator/config
 
-# Change Background to sth cool
-COPY assets/mr-robot-wallpaper.png  /usr/share/extra/backgrounds/bg_default.png
+# Nerd fonts (remote)
+ADD https://github.com/ryanoasis/nerd-fonts/releases/download/${NERD_FONTS_VERSION}/${NERD_FONTS_ARCHIVE} /tmp/${NERD_FONTS_ARCHIVE}
+RUN mkdir -p /copy/configs/usr/local/share/fonts
+RUN unzip /tmp/${NERD_FONTS_ARCHIVE} -d /copy/configs/usr/local/share/fonts
 
-# Install Starship
-RUN wget https://starship.rs/install.sh
-RUN chmod +x install.sh
-RUN ./install.sh -y
+# Starship (remote)
+ADD https://starship.rs/install.sh /copy/starship/install.sh
+RUN chmod +x /copy/starship/install.sh
 
-# Add Starship to bashrc
-RUN echo 'eval "$(starship init bash)"' >> .bashrc
 
-# Add Starship Theme
-COPY config/starship.toml .config/starship.toml
+######### KASM Container Here ###########
 
-# Install Hack Nerd Font
-RUN wget https://github.com/ryanoasis/nerd-fonts/releases/download/v2.1.0/Hack.zip
-RUN unzip Hack.zip -d /usr/local/share/fonts
+FROM kasmweb/core-ubuntu-bionic:1.10.0
+USER root
+
+ENV HOME /home/kasm-default-profile
+ENV STARTUPDIR /dockerstartup
+ENV INST_SCRIPTS $STARTUPDIR/install
+WORKDIR $HOME
 
-# Install Terminator
-RUN apt -y install terminator
 
-# Set up Nerd font in Terminator
-RUN mkdir .config/terminator
-COPY config/terminator.toml .config/terminator/config
+######### Customize Container Here ###########
 
-# Install XFCE Dark Theme
-RUN apt install numix-gtk-theme
+# Install packages and configure the container
+RUN --mount=type=bind,from=temp-files,source=/copy,target=/tmp/copy \
+    # Make APT/DPKG aware that we're building an image, so no user interaction is possible
+    # (only for this specific shell)
+    export DEBIAN_FRONTEND=noninteractive && \
+    # Fix locales when installing packages
+    # (only for this specific shell)
+    export LC_ALL=C \
+    && \
+        # Upgrade the system
+        apt-get update && \
+        apt-get -y full-upgrade \
+    && \
+        # Install packages
+        apt-get -y install --no-install-recommends \
+            numix-gtk-theme \
+            openvpn \
+            terminator \
+    && \
+        # Clear APT caches
+        apt-get -y clean && \
+        rm -rf /var/lib/apt/lists/* \
+    && \
+        # Copy config files from mounted /tmp/copy/configs directory
+        mkdir -p root/.config/terminator && \
+        cp -R /tmp/copy/configs/* / && \
+        # Install Starship
+        /tmp/copy/starship/install.sh -y && \
+        # Configure Bash for Starship
+        echo 'eval "$(starship init bash)"' >> .bashrc
 
 
 ######### End Customizations ###########