Update node12 permissions for npm install

Moves to an npm install without using a root user and chmod.

This was causing significant delay when using huge modules like
the AWS SDK.

If this affects you in some way, just raise an issue and we
will look into it.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

template/node12/Dockerfile

@@ -10,24 +10,21 @@ RUN chmod +x /usr/bin/fwatchdog
 RUN apk --no-cache add curl ca-certificates \
     && addgroup -S app && adduser -S -g app app
 
-WORKDIR /root/
-
 # Turn down the verbosity to default level.
 ENV NPM_CONFIG_LOGLEVEL warn
 
-RUN mkdir -p /home/app
+RUN chmod 777 /tmp
+
+USER app
+
+RUN mkdir -p /home/app/function
 
 # Wrapper/boot-strapper
 WORKDIR /home/app
 COPY package.json ./
 
 # This ordering means the npm installation is cached for the outer function handler.
 RUN npm i
-# chmod for tmp is for a buildkit issue (@alexellis)
-RUN chown app:app -R /home/app \
-    && chmod 777 /tmp
-
-USER app
 
 # Copy outer function handler
 COPY index.js ./
@@ -38,7 +35,7 @@ COPY index.js ./
 WORKDIR /home/app/function
 COPY function/*.json ./
 
-RUN npm i || :
+RUN npm i
 
 # COPY function files and folders
 COPY function/ ./
@@ -57,9 +54,9 @@ ENV upstream_url="http://127.0.0.1:3000"
 ENV exec_timeout="10s"
 ENV write_timeout="15s"
 ENV read_timeout="15s"
+
 ENV prefix_logs="false"
 
 HEALTHCHECK --interval=3s CMD [ -e /tmp/.lock ] || exit 1
 
 CMD ["fwatchdog"]
-