Add ability to publish to bintray and central

[wiktorolko]

Added the maven-publish to enable releasing artefacts to maven repository.

My goal is to have 0.4.0 released to 'http://maven.snplow.com/releases/'. Could you @BenFradet help here?

To release the 0.4.0 artifact all you need to do is:

• add maven repo credentials to build.gradle
• invoke './gradlew publish'

[BenFradet]

I think we want to aim for central directly, we can definitely help with those creds 👍

[wiktorolko]

OK, if you think that we should aim for mavenCentral, then there are some additional changes that needs to be made.

I'll follow this guide https://medium.com/@nmauti/sign-and-publish-on-maven-central-a-project-with-the-new-maven-publish-gradle-plugin-22a72a4bfd4b and update the PR with necessary changes.

[wiktorolko]

I've ended-up following the official guide: https://central.sonatype.org/pages/gradle.html

To release the jar you'll need to:

• Modify credentials in the gradle.properties file
• Invoke ./gradlew uploadArchives

[wiktorolko]

I guess this PR should be merged to develop.
Then a new one should be created: develop->master.
Then you could checkout master, modify credentials in gradle.properties (it should only take place in your local env and should never be pushed to git repo), invoke ./gradlew uploadArchives.

[wiktorolko]

Is there anything I can do to have it released?

[BenFradet]

Sorry, I was "out" last week.

We actually don't use sonatype directly but rather bintray which is then mirrored. It seems there is a plugin for gradle: https://github.com/bintray/gradle-bintray-plugin.

We usually have the following four env variables:

• BINTRAY_USER
• BINTRAY_API_KEY
• SONA_USER
• SONA_PASS

in our .travis.yml (I can take care of inputting those).

and then a small script that actually takes care of publishing.

You can check out https://github.com/snowplow/snowplow-android-tracker/blob/master/.travis/deploy.sh and https://github.com/snowplow/snowplow-android-tracker/blob/master/.travis.yml#L46-L51

The example above only publishes to bintray but I'd think it's not terribly hard to do the mirroring with the mavenCentralSync closure from the plugin.

[wiktorolko]

I've followed the README of the gradle-bintray-plugin, but didn't have a chance to test it e2e ... I hope it will work ;)

[wiktorolko]

@BenFradet would you have some time this week to approve this PR, merge to master and do the release?

The build.gradle:

• was created according to the description here: https://github.com/bintray/gradle-bintray-plugin. I've made sure that all the mavenCentral requirements are met (signing, authors, descriptions, ...)
• is using the four env variables that you've mentioned (BINTRAY_USER, BINTRAY_API_KEY, SONA_USER, SONA_PASS)

[BenFradet]

Looks great, just a couple of minor comments 👍

[BenFradet]

it's snowplow-maven

[wiktorolko]

Fixed

[BenFradet]

I think we need the .git extension

[wiktorolko]

You are right (verified examples in the gradle-bintray-plugin). Fixed.

[BenFradet]

I don't think we have a key so this will most likely fail

[wiktorolko]

It's obligatory to have signing enabled.

https://github.com/bintray/gradle-bintray-plugin#Maven_Central_Sync

(...) also files must be signed to be sent to Maven Central, so GPG file signing should be enabled (see above) if Maven Central sync is enabled

Here is an article how to create a signature:
https://medium.com/@nmauti/publishing-a-project-on-maven-central-8106393db2c3

[BenFradet]

ah indeed, didn't know bintray did it for us: https://github.com/bintray/gradle-bintray-plugin#gpg-file-signing

[BenFradet]

Looks great, can you just make the deploy.sh file executable?

[wiktorolko]

I didn't even know that it's possible ;) Good - learning new things :)

[BenFradet]

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[wiktorolko]

This PR got merged to develop, what needs to be done to deploy it to maven central?

[BenFradet]

sorry this dropped off my radar, I'll try publishing an RC today