Test release

SBT dependency:

"com.softwaremill.testrelease2" %% "core" % "0.29"

How the release process works

The release process is broken into two steps:

1. local: sbt commitRelease. This sbt command prepares the next release: runs the tests, updates version.sbt, creates the git tag, commits the changes and finally asks the user to push the changes.
2. remote: sbt publishRelease. This sbt command should be run on Travis, triggered when a new tag is pushed. It publishes the artifacts to sonatype, and invokes repository release.

See releaseProcess in release.sbt for details on how the release steps are defined in both cases.

Configuration

To run the release, travis needs to know the keypair to sign the artifacts, as well as the username/password to access oss.sonatype.org. These values all need to be prepared in file locally, then packaged, encrypted using a secret that's only known to travis, and committed.

Here's how to do that:

1. create secring.asc and pubring.asc files with the PGP private/public keys
2. create a credentials.sbt file with the following content:

credentials += Credentials("Sonatype Nexus Repository Manager",
                           "oss.sonatype.org",
                           "SONATYPE_USERNAME",
                           "SONATYPE_PASSWORD")

pgpPassphrase := Some("KEY_PASSWORD").map(_.toArray)

3. create an archive: tar cvf secrets.tar secring.asc pubring.asc credentials.sbt
4. login to travis: travis login (you'll need the travis CLI to do that)
5. encrypt the archive: travis encrypt-file secrets.tar --add

This should have two effects:

1. an encrypted file should be created in the top-level directory: secrets.tar.enc. This file should be committed. Take care not to commit secrets.tar, though :).
2. a before_install segment should be added to travis.yml. This segment decrypts the secrets file, using environmental variables provided by travis

In the before_install section, there should also be an entry unpacking the secrets file: tar xvf secrets.tar.