Publishing Scala Projects
This page will discuss common topics around publishing your Scala projects for others to use
Publishing Locally
package build
import mill._, scalalib._, publish._
object foo extends ScalaModule with PublishModule {
def scalaVersion = "2.13.8"
def publishVersion = "0.0.1"
def pomSettings = PomSettings(
description = "Hello",
organization = "com.lihaoyi",
url = "https://github.com/lihaoyi/example",
licenses = Seq(License.MIT),
versionControl = VersionControl.github("lihaoyi", "example"),
developers = Seq(Developer("lihaoyi", "Li Haoyi", "https://github.com/lihaoyi"))
)
}
This is an example ScalaModule
with added publishing capabilities via
PublishModule
. This requires that you define an additional
publishVersion
and pomSettings
with the relevant metadata, and provides
the .publishLocal
and publishSigned
tasks for publishing locally to the
machine or to the central maven repository
> mill foo.publishLocal # publish specific modules
> mill __.publishLocal # publish every eligible module
Publishing Artifact(com.lihaoyi,foo_2.13,0.0.1) to ivy repo...
publishLocal
publishes the artifacts to the ~/.ivy2/local
folder on your
machine, allowing them to be resolved by other projects and build tools. This
is useful as a lightweight way of testing out the published artifacts, without
the setup overhead and long latencies of publishing artifacts globally accessible
to anyone in the world.
Publishing to Sonatype Maven Central
Once you’ve mixed in PublishModule
, apart from publishing locally, you can also publish
your project’s modules to maven central
GPG
If you’ve never created a keypair before that can be used to sign your artifacts you’ll need to do this. Sonatype’s GPG Documentation has the instructions on how to do this
Publishing Secrets
Mill uses the following environment variables as a way to pass the necessary secrets for publishing:
# The LHS and RHS of the User Token, accessible through the sonatype
# website `Profile` / `User Token` / `Access User Token`
export MILL_SONATYPE_USERNAME=...
export MILL_SONATYPE_PASSWORD=...
# The base-64 encoded PGP key, which can be encoded in the following way
# for each OS:
#
# MacOS or FreeBSD
# gpg --export-secret-key -a $LONG_ID | base64
#
# Ubuntu (assuming GNU base64)
# gpg --export-secret-key -a $LONG_ID | base64 -w0
#
# Arch
# gpg --export-secret-key -a $LONG_ID | base64 | sed -z 's;\n;;g'
#
# Windows
# gpg --export-secret-key -a %LONG_ID% | openssl base64
export MILL_PGP_SECRET_BASE64=...
# The passphrase associated with your PGP key
export MILL_PGP_PASSPHRASE=...
Publishing
You can publish all eligible modules in your Mill project using
the default task of the
External Module mill.scalalib.PublishModule
:
mill mill.scalalib.PublishModule/
You can also specify individual modules you want to publish via a selector:
mill mill.scalalib.PublishModule/ foo.publishArtifacts
The default URL for publishing to sonatype’s Maven Central is oss.sonatype.org
.
Newer projects registered on sonatype may need to publish using s01.oss.sonatype.org
.
In that case, you can pass in a --sonatypeUri
:
mill mill.scalalib.PublishModule/ \
--sonatypeUri https://s01.oss.sonatype.org/service/local
This also allows you to publish to your own internal corporate sonatype deployment,
by passing in --sonatypeUri example.company.com
instead.
Since Feb. 2021 any new Sonatype accounts have been created on
The symptom of using the "wrong" URL for publishling is typically a 403 error code, in response to the publish request. Typically
|
Publishing Using Github Actions
To publish on Github Actions, you can use something like this:
# .github/workflows/publish-artifacts.yml
name: Publish Artifacts
on:
push:
tags:
- '**'
workflow_dispatch:
jobs:
publish-artifacts:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v3
- uses: actions/setup-java@v3
with:
distribution: 'temurin'
java-version: '17'
- run: ./mill mill.scalalib.PublishModule/
env:
MILL_PGP_PASSPHRASE: ${{ secrets.MILL_PGP_PASSPHRASE }}
MILL_PGP_SECRET_BASE64: ${{ secrets.MILL_PGP_SECRET_BASE64 }}
MILL_SONATYPE_PASSWORD: ${{ secrets.MILL_SONATYPE_PASSWORD }}
MILL_SONATYPE_USERNAME: ${{ secrets.MILL_SONATYPE_USERNAME }}
Where MILL_PGP_PASSPHRASE
, MILL_PGP_SECRET_BASE64
, MILL_SONATYPE_PASSWORD
, and
MILL_SONATYPE_USERNAME
configured for the repository’s or organization’s Github Actions
workflows. See
Using Secrets in Github Actions
for more details.
Non-Staging Releases (classic Maven uploads)
If the site does not support staging releases as oss.sonatype.org
and s01.oss.sonatype.org
do (for
example, a self-hosted OSS nexus site), you can pass in the
--stagingRelease false
option to simply upload release artifacts to corresponding
maven path under sonatypeUri
instead of staging path.
mill mill.scalalib.PublishModule/ \
foo.publishArtifacts \
lihaoyi:$SONATYPE_PASSWORD \
--sonatypeUri http://example.company.com/release \
--stagingRelease false