Created a Dockerfile for yacy base on Alpine Linux

docker/Dockerfile.alpine

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+# Build a docker image from latest YaCy sources on Alpine Linux
+
+# Base image : latest stable official jdk image from Docker based on Alpine Linux 
+FROM java:alpine
+
+# trace java version
+RUN java -version
+
+# Install needed packages not in base image
+RUN apk update && \
+	apk add --no-cache git \
+	curl \
+	gnupg
+
+# set current working dir
+WORKDIR /tmp
+
+# --- Begin of apache ant install : from binary distribution because ant is not in alpine packages
+
+# 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
+    
+# set ant required environment variables
+ENV ANT_HOME /opt/ant 
+ENV PATH ${PATH}:/opt/ant/bin
+    
+# --- End of apache ant install
+
+# set current working dir
+WORKDIR /opt
+
+
+# clone main YaCy git repository (we need to clone git repository to generate correct version when building from source)
+RUN git clone https://github.com/yacy/yacy_search_server.git
+
+# trace content of source directory
+RUN ls -la /opt/yacy_search_server
+
+# set current working dir
+WORKDIR /opt/yacy_search_server
+	
+# Compile with ant
+RUN ant compile
+
+# Set initial admin password : "docker" (encoded with custom yacy md5 function net.yacy.cora.order.Digest.encodeMD5Hex())
+RUN sed -i "/adminAccountBase64MD5=/c\adminAccountBase64MD5=MD5:e672161ffdce91be4678605f4f4e6786" /opt/yacy_search_server/defaults/yacy.init
+
+# Create user and group yacy : this user will be used to run YaCy main process
+RUN addgroup yacy && adduser -S -G yacy -H -D yacy
+
+# Set ownership of yacy install directory to yacy user/group
+RUN chown yacy:yacy -R /opt/yacy_search_server
+
+# make some cleaning to reduce image size
+RUN rm -rf .git && \
+	rm -f /tmp/apache-ant-${ANT_VERSION}-bin.tar.gz && \
+	rm -rf /opt/ant
+
+# Expose port 8090
+EXPOSE 8090
+
+# Set data volume : yacy data and configuration will persist aven after container stop or destruction
+VOLUME ["/opt/yacy_search_server/DATA"]
+
+# Next commands run as yacy as non-root user for improved security
+USER yacy
+
+# Start yacy in debug mode (-d) to display console logs and to wait for yacy process
+CMD sh /opt/yacy_search_server/startYACY.sh -d