Compacted some instructions to reduce final image size

docker/Dockerfile.alpine

@@ -8,9 +8,7 @@ RUN java -version
 
 # Install needed packages not in base image
 RUN apk update && \
-	apk add --no-cache git \
-	curl \
-	gnupg
+	apk add --no-cache curl
 
 # set current working dir
 WORKDIR /tmp
@@ -20,18 +18,23 @@ WORKDIR /tmp
 # set ant version once in a environment variable
 ENV ANT_VERSION 1.9.7
 
-# get ant binary file from a mirror and PGP file signature from main repository 
-RUN curl http://www.eu.apache.org/dist//ant/binaries/apache-ant-${ANT_VERSION}-bin.tar.gz > apache-ant-${ANT_VERSION}-bin.tar.gz && \
-	curl https://www.apache.org/dist/ant/binaries/apache-ant-${ANT_VERSION}-bin.tar.gz.asc > apache-ant-${ANT_VERSION}-bin.tar.gz.asc
-
-# import gpg keys from main repository and verify binary file signature
-RUN curl https://www.apache.org/dist/ant/KEYS | gpg --import && \
-	gpg --verify apache-ant-${ANT_VERSION}-bin.tar.gz.asc
-
-# extract binary, make /opt directory and move extracted ant to /opt/ant
-RUN tar xzf apache-ant-${ANT_VERSION}-bin.tar.gz && \
-    mkdir /opt && \
-    mv apache-ant-${ANT_VERSION} /opt/ant
+# All in one step to reduce image size growth :
+# - add gnupg package
+# - get ant binary file from a mirror and PGP file signature from main repository
+# - import gpg keys from main repository and verify binary file signature
+# - extract binary, make /opt directory, move extracted ant to /opt/ant
+# - remove archive and gnupg package
+RUN apk update && \
+	apk add --no-cache gnupg && \
+	curl http://www.eu.apache.org/dist//ant/binaries/apache-ant-${ANT_VERSION}-bin.tar.gz > apache-ant-${ANT_VERSION}-bin.tar.gz && \
+	curl https://www.apache.org/dist/ant/binaries/apache-ant-${ANT_VERSION}-bin.tar.gz.asc > apache-ant-${ANT_VERSION}-bin.tar.gz.asc && \
+	curl https://www.apache.org/dist/ant/KEYS | gpg --import && \
+	gpg --verify apache-ant-${ANT_VERSION}-bin.tar.gz.asc && \
+	tar xzf apache-ant-${ANT_VERSION}-bin.tar.gz && \
+	mkdir /opt && \
+	mv apache-ant-${ANT_VERSION} /opt/ant && \
+	rm -f apache-ant-${ANT_VERSION}-bin.tar.gz && \
+	apk del gnupg
     
 # set ant required environment variables
 ENV ANT_HOME /opt/ant 
@@ -44,7 +47,11 @@ WORKDIR /opt
 
 
 # clone main YaCy git repository (we need to clone git repository to generate correct version when building from source)
-RUN git clone https://github.com/yacy/yacy_search_server.git
+# add and delete git package within this same step to avoid image size growth
+RUN apk update && \
+	apk add --no-cache git && \
+	git clone https://github.com/yacy/yacy_search_server.git && \
+	apk del git
 
 # trace content of source directory
 RUN ls -la /opt/yacy_search_server
@@ -66,7 +73,6 @@ RUN chown yacy:yacy -R /opt/yacy_search_server
 
 # make some cleaning to reduce image size
 RUN rm -rf .git && \
-	rm -f /tmp/apache-ant-${ANT_VERSION}-bin.tar.gz && \
 	rm -rf /opt/ant
 
 # Expose port 8090