lock build again

Dockerfile

@@ -1,14 +1,42 @@
-FROM docker.io/library/node:16-alpine
+# There's an issue with node:16-alpine.
+# On Raspberry Pi, the following crash happens:
 
-# Install Linux packages
-RUN apk add -U --no-cache wireguard-tools dumb-init
+# #FailureMessage Object: 0x7e87753c
+# #
+# # Fatal error in , line 0
+# # unreachable code
+# #
+# #
+# #
+
+FROM docker.io/library/node:14-alpine@sha256:dc92f36e7cd917816fa2df041d4e9081453366381a00f40398d99e9392e78664 AS build_node_modules
 
 # Copy Web UI
 COPY src/ /app/
 WORKDIR /app
 RUN npm ci --production
+
+# Copy build result to a new image.
+# This saves a lot of disk space.
+FROM docker.io/library/node:14-alpine@sha256:dc92f36e7cd917816fa2df041d4e9081453366381a00f40398d99e9392e78664
+COPY --from=build_node_modules /app /app
+
+# Move node_modules one directory up, so during development
+# we don't have to mount it in a volume.
+# This results in much faster reloading!
+#
+# Also, some node_modules might be native, and
+# the architecture & OS of your development machine might differ
+# than what runs inside of docker.
+RUN mv /app/node_modules /node_modules
+
+# Enable this to run `npm run serve`
 RUN npm i -g nodemon
-RUN mv /app/node_modules/ /node_modules/
+
+# Install Linux packages
+RUN apk add -U --no-cache \
+  wireguard-tools \
+  dumb-init
 
 # Expose Ports
 EXPOSE 51820/udp
@@ -18,4 +46,5 @@ EXPOSE 51821/tcp
 ENV DEBUG=Server,WireGuard
 
 # Run Web UI
+WORKDIR /app
 CMD ["/usr/bin/dumb-init", "node", "server.js"]