Run as rootless user & improve build cache

Dockerfile

@@ -9,14 +9,14 @@ FROM node:16.14.0
 # Set working directory
 WORKDIR /opt/ass/
 
-# Copy directory files (config.json, source files etc.)
+# create rootless user with uid/gid as 1000
-COPY . ./
+RUN groupadd -g 1000 -o ass && useradd -m -u 1000 -g 1000 -o -s /bin/bash ass
 
-# Update npm to at least npm 8,
+# Set permissions for rootless user
-# then install dependencies
+RUN chown -R ass /opt/ass/ && chmod -R 774 /opt/ass/
-RUN npm i -g npm@8 typescript && \
+
-    npm i --save-dev && \
+# run container as previously created user
-    npm run build
+USER ass
 
 # Ensure these directories & files exist for compose volumes
 RUN mkdir -p /opt/ass/uploads/thumbnails/ && \
@@ -25,5 +25,14 @@ RUN mkdir -p /opt/ass/uploads/thumbnails/ && \
     touch /opt/ass/auth.json && \
     touch /opt/ass/data.json
 
+# Copy directory files (config.json, source files etc.)
+COPY . ./
+
+# Update npm to at least npm 8, then install dependencies
+RUN npm i -g npm@8 typescript && \
+    npm i --save-dev && \
+    npm run build && \
+    chown -R ass /usr/local/bin/npm
+
 # Start ass
 CMD npm start