Get latest version number of a Maven package

Maven is a well known software project management and comprehension tool with a great package management solution. in this post, we’ll discuss a simple solution to acquire latest version number of a Maven package.

Any maven package could be a candidate for this tutorial, we chose Google’s Libphonenumber because its a regularly updated package with important changes.

Maven Package

A Maven package is the compiled code and package it in its distributable format, such as a JAR. each Maven package comes with a maven-metadata.xml file where Maven stores basic information about artifacts such as versioning information, release time etc.

Implement:

a. Choose a package: To choose a package you can visit https://mvnrepository.com/ and search for the package you need. our choice is: https://mvnrepository.com/artifact/com.googlecode.libphonenumber/libphonenumber

b. Find maven-metadata.xml URL: you can click on one of the versions like: https://mvnrepository.com/artifact/com.googlecode.libphonenumber/libphonenumber/8.12.53
then copy link from jar file download button, which will be like:
https://repo1.maven.org/maven2/com/googlecode/libphonenumber/libphonenumber/8.12.53/libphonenumber-8.12.53.jar
then remove version and file name and append “maven-metadata.xml” to it. your url will be sth like:
https://repo1.maven.org/maven2/com/googlecode/libphonenumber/libphonenumber/maven-metadata.xml

c. Bash scripting:
We will use bash for automating the process:

# get latest version number from maven metadata, you can replace &quotlatest&quot with &quotrelease&quot to get latest release version.
latest_version=`curl https://repo.maven.apache.org/maven2/com/googlecode/libphonenumber/libphonenumber/maven-metadata.xml 2>/dev/null | grep latest | grep -o -P '(?<=\>).*(?=\<)'`
# update file modification timestamp, and craete it if it doesn't exist.
touch /var/tmp/libphone_version
# read latest saved version
ver=`cat /var/tmp/libphone_version`
# use default value: &quot5.12.50&quot if file is empty.
previous_version=${ver:=5.12.50}
# function to compare semantic version
# From: https://stackoverflow.com/a/4025065/4134048 by Dennis Williamson
vercomp () {
    if [[ $1 == $2 ]]
    then
        return 0
    fi
    local IFS=.
    local i ver1=($1) ver2=($2)
    # fill empty fields in ver1 with zeros
    for ((i=${#ver1[@]}; i<${#ver2[@]}; i++))
    do
        ver1[i]=0
    done
    for ((i=0; i<${#ver1[@]}; i++))
    do
        if [[ -z ${ver2[i]} ]]
        then
            # fill empty fields in ver2 with zeros
            ver2[i]=0
        fi
        if ((10#${ver1[i]} > 10#${ver2[i]}))
        then
            return 1
        fi
        if ((10#${ver1[i]} < 10#${ver2[i]}))
        then
            return 2
        fi
    done
    return 0
}
# Compare two versions
vercomp $previous_version $latest_version
# Fail if versions are not the same
if [ $? != 0  ]; then
        echo &quotOops!&quot
# Print Jar download url
        echo &quothttps://repo1.maven.org/maven2/com/googlecode/libphonenumber/libphonenumber/8.12.53/libphonenumber-$latest_version.jar&quot
# Save version number
        echo &quotlatest_version&quot > /var/tmp/libphone_version
        exit 1;
else
        echo &quotOk!&quot
        exit 0;
fi

you can use the output and exit code to sent alerts and notification.