Update to Alpine 3.10 and PowerDNS 4.2.1, plus minor refactoring

Dockerfile

@@ -1,30 +1,48 @@
-FROM alpine:3.9
+FROM alpine:3.10
 MAINTAINER Christoph Wiechert <wio@psitrax.de>
 
-ENV REFRESHED_AT="2019-10-10" \
-    POWERDNS_VERSION=4.2.0 \
+ENV REFRESHED_AT="2019-12-02" \
+    POWERDNS_VERSION=4.2.1 \
+    POWERDNS_TARBALL_SHA256="f65019986b8fcbb1c6fffebcded04b2b397b84395830f4c63e8d119bcfa1aa28" \
     MYSQL_AUTOCONF=true \
     MYSQL_HOST="mysql" \
     MYSQL_PORT="3306" \
     MYSQL_USER="root" \
     MYSQL_PASS="root" \
     MYSQL_DB="pdns"
 
-RUN apk --update add libpq sqlite-libs libstdc++ libgcc mariadb-client mariadb-connector-c && \
-    apk add --virtual build-deps \
-      g++ make mariadb-dev postgresql-dev sqlite-dev curl boost-dev mariadb-connector-c-dev && \
-    curl -sSL https://downloads.powerdns.com/releases/pdns-$POWERDNS_VERSION.tar.bz2 | tar xj -C /tmp && \
-    cd /tmp/pdns-$POWERDNS_VERSION && \
+RUN apk --update --no-cache add \
+      libgcc \
+      libpq \
+      libstdc++ \
+      mariadb-client \
+      mariadb-connector-c \
+      sqlite-libs && \
+    apk --update --no-cache add --virtual .build-deps \
+      boost-dev \
+      curl \
+      g++ \
+      make \
+      mariadb-connector-c-dev \
+      mariadb-dev \
+      postgresql-dev \
+      sqlite-dev && \
+    curl -sSL -o /tmp/pdns-$POWERDNS_VERSION.tar.bz2 https://downloads.powerdns.com/releases/pdns-$POWERDNS_VERSION.tar.bz2 && \
+    echo "${POWERDNS_TARBALL_SHA256}  /tmp/pdns-${POWERDNS_VERSION}.tar.bz2" | sha256sum -c && \
+    cd /tmp/ && \
+    tar xjf pdns-${POWERDNS_VERSION}.tar.bz2 && \
+    cd /tmp/pdns-${POWERDNS_VERSION} && \
     ./configure --prefix="" --exec-prefix=/usr --sysconfdir=/etc/pdns \
       --with-modules="bind gmysql gpgsql gsqlite3" --without-lua --disable-lua-records && \
-    make && make install-strip && cd / && \
+    make && make install-strip && \
+    cd / && \
     mkdir -p /etc/pdns/conf.d && \
-    addgroup -S pdns 2>/dev/null && \
-    adduser -S -D -H -h /var/empty -s /bin/false -G pdns -g pdns pdns 2>/dev/null && \
-    cp /usr/lib/libboost_program_options-mt.so* /tmp && \
-    apk del --purge build-deps && \
-    mv /tmp/libboost_program_options-mt.so* /usr/lib/ && \
-    rm -rf /tmp/pdns-$POWERDNS_VERSION /var/cache/apk/*
+    addgroup -S pdns && \
+    adduser -S -D -H -h /var/empty -s /bin/false -G pdns -g pdns pdns && \
+    cp -d /usr/lib/libboost_program_options.so* /tmp && \
+    apk del --purge .build-deps && \
+    mv /tmp/libboost_program_options.so* /usr/lib/ && \
+    rm -rf /tmp/pdns-$POWERDNS_VERSION.tar.bz2 /tmp/pdns-$POWERDNS_VERSION /var/cache/apk/*
 
 ADD schema.sql pdns.conf /etc/pdns/
 ADD entrypoint.sh /