Simplify Dockerfile (zcash#6906)

Author: y4ssi

contrib/docker/Dockerfile

@@ -1,4 +1,4 @@
-FROM debian:11
+FROM debian:12
 
 RUN apt-get update \
   && apt-get install -y gnupg2 apt-transport-https curl
@@ -14,7 +14,7 @@ ARG ZCASHD_USER=zcashd
 ARG ZCASHD_UID=2001
 
 RUN apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys $ZCASH_SIGNING_KEY_ID \
-  && echo "deb [arch=amd64] https://apt.z.cash/ bullseye main" > /etc/apt/sources.list.d/zcash.list \
+  && echo "deb [arch=amd64] https://apt.z.cash/ bookworm main" > /etc/apt/sources.list.d/zcash.list \
   && apt-get update
 
 RUN if [ -z "$ZCASH_VERSION" ]; \
@@ -23,15 +23,18 @@ RUN if [ -z "$ZCASH_VERSION" ]; \
     fi; \
     zcashd --version
 
-RUN useradd --home-dir /srv/$ZCASHD_USER \
+RUN useradd --home-dir "/srv/$ZCASHD_USER" \
             --shell /bin/bash \
             --create-home \
-            --uid $ZCASHD_UID\
-            $ZCASHD_USER
-USER $ZCASHD_USER
-WORKDIR /srv/$ZCASHD_USER
-RUN mkdir -p /srv/$ZCASHD_USER/.zcash/ \
-    && touch /srv/$ZCASHD_USER/.zcash/zcash.conf
+            --uid "$ZCASHD_UID" \
+            "$ZCASHD_USER"
+
+RUN mkdir -p "/srv/$ZCASHD_USER/.zcash/" \
+    && touch "/srv/$ZCASHD_USER/.zcash/zcash.conf" \
+    && chown -R zcashd "/srv/$ZCASHD_USER"
+
+WORKDIR "/srv/$ZCASHD_USER"
+ENV HOME="/srv/$ZCASHD_USER"
 
 ADD entrypoint.sh /entrypoint.sh
 ENTRYPOINT ["/entrypoint.sh"]