Create a github action that release on Maven when we create a tag

[JFCote]

The goal of this task is to automate an event when someone creates a tag.
As soon as the tag is created, the associated github action is started and all the steps of a release would be automatically done.
Minutes later, we would have access to the latest version on Maven.

First step is to retrieve the step of the release process from @jmini and to code them in a github action script. Then, get the proper access and put them in the secrets. Then testing with a real release.

[jmini]

To create a release:

1) Set the credentials to be able to push to nexus:

export SONATYPE_USER=<user name (best is to use a token)>
export SONATYPE_PASSWORD=<password (best is to use a token)>

2) Change the version and commit.

2a) change the version from a.b-SNAPSHOT to a.b => Example e700b5f

When commit (2a) is created, run ./gradlew publishToSonatype
Create tag a.b on commit (2a) and push it.

2b) change the version from a.b to a.(b+1)-SNAPSHOT => Example 0dcdfd5

For this complete 2) bock an alternative is to use the plugin id 'net.researchgate.release' version '2.6.0'
Check the project https://github.com/OpenAPITools/empoa/

Then the plugin is performing the same step when running ./gradlew release -Prelease.useAutomaticVersion=true

3) Activities in Nexus

In the Staging Repositories (https://oss.sonatype.org/#stagingRepositories)

Select the corresponding repository (example orgopenapitools-1292)
Check the content (uploaded jars, pom files)

• Click on the Close button
• Wait until the operation is done
• Click on the Release button

It is also possible to automate those steps inside the gradle plugin (probably nexus publishing).
I like checking manually before publishing.

4) Other prerequite

You need to be able to sign (GPG) your jars and upload the signature to Nexus.
Everything is prepared with apply plugin: 'signing'

But you need to have the infrastructure available on the build machine.

[wing328]

FYI. To sign the JAR, run the following:

./gradlew publishToSonatype -Psigning.gnupg.keyName=3E99C7FD4C83EB0E56D5503678737DD36C998877

where 3E99C7FD4C83EB0E56D5503678737DD36C998877 is the key name one can find from gpg --list-key