use base to access download.sh

Author: joecorall

alpaca/Dockerfile

@@ -1,7 +1,7 @@
 # syntax=docker/dockerfile:1.5.1
-FROM gradle:6.9.4-jdk11@sha256:a21f8e1124fefb9b2affc85b7fa3bc856297056678b5cc882a61a8d6249da3a2 AS builder
+FROM base AS download
 
-WORKDIR /build
+WORKDIR /opt/download
 
 # renovate: datasource=github-releases depName=alpaca packageName=islandora/alpaca
 ARG ALPACA_VERSION=2.4.0
@@ -12,6 +12,12 @@ RUN download.sh \
       --sha256 "${ALPACA_SHA256}" \
       --dest .
 
+FROM gradle:6.9.4-jdk11@sha256:a21f8e1124fefb9b2affc85b7fa3bc856297056678b5cc882a61a8d6249da3a2 AS builder
+
+WORKDIR /build
+
+COPY --from=base /opt/download .
+
 RUN --mount=type=cache,id=alpaca-gradle,sharing=locked,target=/root/.gradle \
     ./gradlew --stacktrace clean build shadowJar --no-daemon