How to migrate gradle publication script to publish OSS library to Bintray's JCenter instead of Sonatype's Maven Central

Question

I am the mantainer of the Java 8 java.time JSP tags library. I have little experience publishing libraries on my own. For the publication of this library I did some research and ended with a gradle build script that you can check in GitHub. The process is a bit clunky but it works in the end.

There seem to be a general understanding that the jcenter() repository is gaining a lot of attention. Probably because of android. Anyway I saw an encouraging blog post and decided to give it a try and migrate that library to JCenter publishing insted of Maven Central. Should be easy.

It is not, for me at least. Probably my fault as my knowledge of Maven, artifacts and all that stuff is poor. Anyway I gave it some hours of research and come up with a new gradle build to publish to my Bintray maven repository. Which, if I'm not wrong, is the first step towards publishing to JCenter.

This is what I have so far:

plugins {
    id "com.jfrog.bintray" version "1.6"
}

apply plugin: 'java'
apply plugin: 'maven-publish'

group = 'net.sargue'
version = '1.1.2'

sourceCompatibility = 1.8
compileJava.options.encoding = 'UTF-8'
compileTestJava.options.encoding = 'UTF-8'

repositories {
    jcenter()
}

configurations {
    testCompile.extendsFrom compileOnly
}

dependencies {
    compileOnly 'javax.servlet:javax.servlet-api:3.0.1'
    compileOnly 'javax.servlet.jsp:javax.servlet.jsp-api:2.2.1'
    compileOnly 'javax.servlet.jsp.jstl:javax.servlet.jsp.jstl-api:1.2.1'

    testCompile 'junit:junit:4.12'
    testCompile 'org.springframework:spring-test:4.1.7.RELEASE'
}

jar {
    manifest {
        attributes 'Implementation-Title': 'Java 8 java.time JSP tags',
                   'Implementation-Version': version
    }
}

task javadocJar(type: Jar) {
    classifier = 'javadoc'
    from javadoc
}

task sourcesJar(type: Jar) {
    classifier = 'sources'
    from sourceSets.main.allSource
}

publishing {
    publications {
        MyPublication(MavenPublication) {
            from components.java
            artifact sourcesJar
            artifact javadocJar
            artifactId 'java-time-jsptags'

            pom.withXml {
                asNode().children().last() + {
                    resolveStrategy = Closure.DELEGATE_FIRST

                    name 'Java 8 java.time JSP tags'
                    description 'JSP tag support for Java 8 java.time (JSR-310)'
                    url 'https://github.com/sargue/java-time-jsptags'

                    scm {
                        connection 'scm:git:[email protected]:sargue/java-time-jsptags.git'
                        developerConnection 'scm:git:[email protected]:sargue/java-time-jsptags.git'
                        url '[email protected]:sargue/java-time-jsptags.git'
                    }

                    licenses {
                        license {
                            name 'The Apache License, Version 2.0'
                            url 'http://www.apache.org/licenses/LICENSE-2.0.txt'
                        }
                    }

                    developers {
                        developer {
                            id 'sargue'
                            name 'Sergi Baila'
                            email '[email protected]'
                        }
                    }
                }
            }
        }
    }
}

bintray {
    user = BINTRAY_USER
    key = BINTRAY_KEY
    publications = ['MyPublication']
    pkg {
        repo = 'maven'
        name = 'java-time-jsptags'
        licenses = ['Apache-2.0']
        vcsUrl = 'https://github.com/sargue/java-time-jsptags.git'
        version {
            name = project.version
            desc = 'Java 8 java.time JSP tags'

            gpg {
                sign = true
                passphrase = BINTRAY_GPG
            }
        }
    }
}

You can find the result of the latest publication on my public Bintray maven repository. You can compare it to the files for the same version currently available on Maven Central.

Congratulations if you are reading this so far, because I haven't formulated ANY question yet. Sorry about that.

My questions:

Is the gradle build script correct and the proper/canonical way? Given that the library is quite simple I found the build script huge and clunky. It is supposed to be easier and it even has a gradle plugin. But the new script is longer than the maven central one.

What about the *.md5 and *.sha1 files? Will be generated by JCenter, Maven Central, the sync proces... or should I do it?

There is some way of testing all these without publishing an actual version of the library given that there is no unpublish capabilities on the repositories? (and for a good reason, eh? leftpad anyone?).

JBaruch JBaruch · Accepted Answer · 2016-04-30T00:52:46

First, great job figuring it out. It looks good and works good.

It's bigger than the other one not because you use Bintray instead of Central, but because you use maven-publish plugin instead of maven, and being more powerful, the config is a bit more verbose. You can use Bintray (and the bintray plugin) with both maven and maven-publish, whatever you prefer.

Re testing it – you can always run a test build against your private repository (click in the Set Me Up button to get instructions on how to set up your Maven and/or Gradle to resolve from it).

Another validation will be syncing to Maven Central. It will fail if something is wrong with your package metadata.

Re md5 and sha1, we don't see a reason to store computable metadata as files on a modern distribution platform, but we send them to Maven Central when we sync.

How to migrate gradle publication script to publish OSS library to Bintray's JCenter instead of Sonatype's Maven Central

1 Answers