Split loader and runtime images

Dockerfile

@@ -1,13 +1,24 @@
-FROM openjdk:17-alpine
+FROM alpine:latest AS loader
 
 ARG PLANTUML_VERSION
 
+RUN apk add --no-cache \
+  wget \
+  ca-certificates
+
+RUN wget \
+  "https://github.com/plantuml/plantuml/releases/download/${PLANTUML_VERSION}/plantuml-${PLANTUML_VERSION#?}.jar" \
+  -O /opt/plantuml.jar
+
+FROM openjdk:17-alpine
+
 ENV LANG en_US.UTF-8
 
-RUN \
-  apk add --no-cache graphviz wget ca-certificates ttf-dejavu && \
-  wget "https://github.com/plantuml/plantuml/releases/download/${PLANTUML_VERSION}/plantuml-${PLANTUML_VERSION#?}.jar" -O /opt/plantuml.jar && \
-  apk del wget ca-certificates
+RUN apk add --no-cache \
+  graphviz \
+  ttf-dejavu
+
+COPY --from=loader /opt/plantuml.jar /opt/plantuml.jar
 
 WORKDIR /data
 VOLUME ["/data"]