Awesome

sbt-ci-release

This is an sbt plugin to help automate releases to Sonatype and Maven Central from GitHub Actions.

git tag pushes are published as regular releases to Maven Central
merge into main commits are published as -SNAPSHOT with a unique version number for every commit

Beware that publishing from GitHub Actions requires you to expose Sonatype credentials as secret environment variables in GitHub Actions jobs. However, secret environment variables are not accessible during pull requests.

Let's get started!

Sonatype
- Optional: create user tokens
sbt
GPG
Secrets
- GitHub Actions
- Travis
Git
FAQ
Adopters
Alternatives

Sonatype

First, follow the instructions in https://central.sonatype.org/pages/ossrh-guide.html to create a Sonatype account and make sure you have publishing rights for a domain name. This is a one-time setup per domain name.

If you don't have a domain name, you can use io.github.<@your_username>. Here is a template you can use to write the Sonatype issue:

Title:
Publish rights for io.github.sbt
Description:
Hi, I would like to publish under the groupId: io.github.sbt.
It's my GitHub account https://github.com/sbt/

Optional: create user tokens

If you prefer not to save your actual username and password in GitHub Actions settings below, generate your user tokens:

login to https://s01.oss.sonatype.org/ (or https://oss.sonatype.org/ if your Sonatype account was created before February 2021),
click your username in the top right, then profiles,
in the tab that was opened, click on the top left dropdown, and select "User Token",
click "Access User Token", and save the name and password parts of the token somewhere safe.

sbt

Next, install this plugin in project/plugins.sbt

// sbt 1 only, see FAQ for 0.13 support
addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "<version>")

By installing sbt-ci-release the following sbt plugins are also brought in:

sbt-dynver: sets the version number based on your git history
sbt-pgp: to cryptographically sign the artifacts before publishing
sbt-sonatype: to publish artifacts to Sonatype
sbt-git: to automatically populate scmInfo

Make sure build.sbt does not define any of the following settings

version: handled by sbt-dynver
publishTo: handled by sbt-ci-release
publishMavenStyle: handled by sbt-ci-release
credentials: handled by sbt-sonatype

Next, define publishing settings at the top of build.sbt

inThisBuild(List(
  organization := "com.github.sbt",
  homepage := Some(url("https://github.com/sbt/sbt-ci-release")),
  // Alternatively License.Apache2 see https://github.com/sbt/librarymanagement/blob/develop/core/src/main/scala/sbt/librarymanagement/License.scala
  licenses := List("Apache-2.0" -> url("http://www.apache.org/licenses/LICENSE-2.0")),
  developers := List(
    Developer(
      "olafurpg",
      "Ólafur Páll Geirsson",
      "olafurpg@gmail.com",
      url("https://geirsson.com")
    )
  )
))

If your sonatype account is new (created after Feb 2021), then the default server location inherited from the the sbt-sonatype plugin will not work, and you should also include the following overrides in your publishing settings

ThisBuild / sonatypeCredentialHost := "s01.oss.sonatype.org"
sonatypeRepository := "https://s01.oss.sonatype.org/service/local"

GPG

Next, create a fresh gpg key that you will share with GitHub Actions and only use for this project.

gpg --gen-key

For real name, you can use anything. For example, this repository uses "sbt-ci-release bot".
For email, use your own email address
For passphrase, generate a random password with a password manager. This will be the environment variables PGP_PASSPHRASE in your CI. Take note of PGP_PASSPHRASE.

At the end you'll see output like this

pub   rsa2048 2018-06-10 [SC] [expires: 2020-06-09]
      $LONG_ID
uid                      $PROJECT_NAME bot <$EMAIL>

Take note of $LONG_ID, make sure to replace this ID from the code examples below. The ID will look something like (a) 6E8ED79B03AD527F1B281169D28FC818985732D9 or something like (b) A4C9 75D9 9C05 E4C7 2163 4BBD ACA8 EB32 0BFE FE2C (in which case delete the spaces to make it look like (a)). A command like this one should do:

# On UNIX
LONG_ID=6E8ED79B03AD527F1B281169D28FC818985732D9

# On Windows
set LONG_ID=6E8ED79B03AD527F1B281169D28FC818985732D9

Next, copy the public gpg signature

# macOS
gpg --armor --export $LONG_ID | pbcopy
# linux
gpg --armor --export $LONG_ID | xclip
# Windows
gpg --armor --export %LONG_ID%

and post the signature to a keyserver: https://keyserver.ubuntu.com/

Select "Submit Key"
Paste in the exported public key
Click on "Submit Public Key".

Ubuntu Keyserver

or run:

# macOS
gpg --keyserver hkp://keyserver.ubuntu.com --send-key $LONG_ID && \
 gpg --keyserver hkp://pgp.mit.edu --send-key $LONG_ID
# linux
gpg --keyserver hkp://keyserver.ubuntu.com --send-key $LONG_ID && \
 gpg --keyserver hkp://pgp.mit.edu --send-key $LONG_ID
# Windows
gpg --keyserver hkp://keyserver.ubuntu.com --send-key %LONG_ID% && \
 gpg --keyserver hkp://pgp.mit.edu --send-key %LONG_ID%

Secrets

Next, you'll need to declare four environment variables in your CI. Open the settings page for your CI provider.

GitHub Actions:

Select Settings -> Secrets and variables -> Actions -> New repository secret to add each of the required variables as shown in the next figure:

When complete, your secrets settings should look like the following:
Travis CI:
- Make sure that "Build pushed branches" setting is enabled.
- If any secrets contain bash special characters, make sure to escape them by wrapping it in single quotes 'my?$ecret', see Travis Environment Variables.

Add the following secrets:

PGP_PASSPHRASE: The randomly generated password you used to create a fresh gpg key.
PGP_SECRET: The base64 encoded secret of your private key that you can export from the command line like here below.

# macOS
gpg --armor --export-secret-keys $LONG_ID | base64 | pbcopy
# Ubuntu (assuming GNU base64)
gpg --armor --export-secret-keys $LONG_ID | base64 -w0 | xclip
# Arch
gpg --armor --export-secret-keys $LONG_ID | base64 | sed -z 's;\n;;g' | xclip -selection clipboard -i
# FreeBSD (assuming BSD base64)
gpg --armor --export-secret-keys $LONG_ID | base64 | xclip
# Windows
gpg --armor --export-secret-keys %LONG_ID% | openssl base64

If you try to display the base64 encoded string in the terminal, some shells (like zsh or fish) may include an additional % character at the end, to mark the end of content which was not terminated by a newline character. This does not indicate a problem. Note for Windows - delete any linebreaks or spaces when copying the encoded string from terminal.

SONATYPE_PASSWORD: The password you use to log into https://s01.oss.sonatype.org/ (or https://oss.sonatype.org/ if your Sonatype account was created before February 2021). Alternatively, the password part of the user token if you generated one above.
SONATYPE_USERNAME: The username you use to log into https://s01.oss.sonatype.org/ (or https://oss.sonatype.org/ if your Sonatype account was created before 2021). Alternatively, the name part of the user token if you generated one above.
(optional) CI_RELEASE: the command to publish all artifacts for stable releases. Defaults to +publishSigned if not provided.
(optional) CI_SNAPSHOT_RELEASE: the command to publish all artifacts for a SNAPSHOT releases. Defaults to +publish if not provided.
(optional) CI_SONATYPE_RELEASE: the command called to close and promote the staged repository. Useful when, for example, also dealing with non-sbt projects to change to sonatypeReleaseAll. Defaults to sonatypeBundleRelease if not provided.

GitHub Actions

Run the following command to install the same release.yml script that is used to release this repository.

mkdir -p .github/workflows && \
  curl -L https://raw.githubusercontent.com/sbt/sbt-ci-release/main/.github/workflows/release.yml > .github/workflows/release.yml

Commit the file and merge into main.

Travis

Skip this step if you're using GitHub Actions. > Unless you have a specific reason to use Travis, we recommend using GitHub Actions because > it's easier to configure.

Next, update .travis.yml to trigger ci-release on successful merge into master and on tag push. There are many ways to do this, but I recommend using Travis "build stages". It's not necessary to use build stages but they make it easy to avoid publishing the same module multiple times from parallel jobs.

First, ensure that git tags are always fetched so that sbt-dynver can pick up the correct version

before_install:
  - git fetch --tags

Next, define test and release build stages

stages:
  - name: test
  - name: release
    if: ((branch = master AND type = push) OR (tag IS present)) AND NOT fork

Lastly, define your build matrix with ci-release at the bottom, for example:

jobs:
  include:
    # stage="test" if no stage is specified
    - name: compile
      script: sbt compile
    - name: formatting
      script: ./bin/scalafmt --test
    # run ci-release only if previous stages passed
    - stage: release
      script: sbt ci-release

Notes:

if we use after_success instead of build stages, we would run ci-release after both formatting and compile. As long as you make sure you don't publish the same module multiple times, you can use any Travis configuration you like
the name: compile part is optional but it makes it easy to distinguish different jobs in the Travis UI

build__48_-sbt-ci-release-_travis_ci

Git

We're all set! Time to manually try out the new setup

Open a PR and merge it to watch the CI release a -SNAPSHOT version
Push a tag and watch the CI do a regular release

git tag -a v0.1.0 -m "v0.1.0"
git push origin v0.1.0

Note that the tag version MUST start with v.

It is normal that something fails on the first attempt to publish from CI. Even if it takes 10 attempts to get it right, it's still worth it because it's so nice to have automatic CI releases. If all is correctly setup, your Travis jobs page will look like this:

Enjoy 👌

Back-publishing support

sbt-ci-release implements a mini-DSL for the Git tag for back publishing purpose, which is useful if you maintain a compiler plugin, library for Scala Native, or an sbt plugin during 2.x migration etc.

v1.2.3[@3.x|@2.n.x|@a.b.c][@command][#comment]

# is used for comments, which is useful if you need to use the same command multiple times
@3.x expands to ++3.x, and if no other commands follow, ;++3.x;publishSigned
@2.13.x expands to ++2.13.x, and if no other commands follow, ;++2.13.x;publishSigned
Other commands such as @foo/publishSigned expands to foo/publishSigned

Case 1: Publish all subprojects for Scala 2.13.15

v1.2.3@2.13.15

Case 2: Publish all subprojects for Scala 3.x

v1.2.3@3.x. Optionally we can add a comment: v1.2.3@3.x#comment.

We can use this to back publish sbt 2.x plugins.

Branch off of v1.2.3 to create release/1.2.3 branch, and send a PR to update sbt version
Tag the brach to v1.2.3@3.x#sbt2.0.0-Mn

Case 3: Publish some subprojects for Scala 2.13.15

v1.2.3@2.13.15@foo/publishSigned

You can create a subproject to aggregate 2 or more subprojects.

Case 4: Publish some subprojects for supported Scala versions

v1.2.3@+foo_native/publishSigned#comment

Branch off of v1.2.3 to create release/1.2.3 branch, and send a PR to update the Scala Native version.
Tag the branch to v1.2.3@+foo_native/publishSigned#native0.5

Case 5: Minimize the use of command

v1.2.3#unique_comment, for example v1.2.3#native0.5_3

If you prefer to keep most of the information in a git branch instead, you can just use the comment functionality.

Branch off of v1.2.3 to create release/1.2.3 branch, and send a PR to: a. Update appropriate dependency (sbt, Scala Native etc) b. Modify the CI_RELEASE environment variable to encode the actions you want to take, like ;++3.x;foo_native/publishSigned. For GitHub Actions, it would be in .github/workflows/release.yml
Tag the branch to v1.2.3#unique_comment. For record keeping, encode the version you're trying to back publishing for e.g. v1.2.3#native0.5_3

FAQ

How do I publish to Sonatype Central?

As of February 2024, Sonatype has released a new portal, called Sonatype Central. Users can configure their libraries to be published via this portal by adding the following to build.sbt:

import xerial.sbt.Sonatype.sonatypeCentralHost

ThisBuild / sonatypeCredentialHost := sonatypeCentralHost

Users can generate a two-part token, containing username and password values, in their account and then set these to the SONATYPE_USERNAME and SONATYPE_PASSWORD environment variables. All other steps should then work as documented.

How do I disable publishing in certain projects?

Add the following to the project settings (works only in sbt 1)

publish / skip := true

How do I publish cross-built projects?

Make sure that projects that compile against multiple Scala versions declare the crossScalaVersions setting in build.sbt, for example

lazy val core = project.settings(
  ...
  crossScalaVersions := List("2.13.1", "2.12.10", "2.11.12")
)

The command +publishSigned (default value for CI_RELEASE) will then publish that project for 2.11, 2.12 and 2.13.

How do I publish cross-built Scala.js projects?

If you publish for multiple Scala.js versions, start by disabling publishing of the non-JS projects when the SCALAJS_VERSION environment variable is defined.

// build.sbt
+ val customScalaJSVersion = Option(System.getenv("SCALAJS_VERSION"))
lazy val myLibrary = crossProject(JSPlatform, JVMPlatform)
  .settings(
    // ...
  )
+  .jvmSettings(
+    skip.in(publish) := customScalaJSVersion.isDefined
+  )

Next, add an additional ci-release step in your CI config to publish the custom Scala.js version

// .travis.yml
  sbt ci-release
+ SCALAJS_VERSION=0.6.31 sbt ci-release

Can I depend on Maven Central releases immediately?

Yes! As soon as CI "closes" the staging repository you can depend on those artifacts with

resolvers ++= Resolver.sonatypeOssRepos("staging")

Use this instead if your Sonatype account was created after February 2021

resolvers +=
  "Sonatype OSS Releases" at "https://s01.oss.sonatype.org/content/repositories/releases"

(optional) Use the coursier command line interface to check if a release was successful without opening sbt

coursier fetch com.github.sbt:scalafmt-cli_2.12:1.5.0 -r sonatype:public

Use -r https://s01.oss.sonatype.org/content/repositories/releases instead if your Sonatype account was created after February 2021.

How do I depend on the SNAPSHOT releases?

Add the following setting

resolvers ++= Opts.resolver.sonatypeOssSnapshots

resolvers +=
  "Sonatype OSS Snapshots" at "https://s01.oss.sonatype.org/content/repositories/snapshots"

if your Sonatype account was created after February 2021.

(optional) With coursier you can do the same thing with -r sonatype:snapshots

coursier fetch com.github.sbt:scalafmt-cli_2.12:1.5.0-SNAPSHOT -r sonatype:snapshots

Use -r https://s01.oss.sonatype.org/content/repositories/snapshots instead if your Sonatype account was created after February 2021.

What about other CIs environments than Travis?

This project uses a github workflow, which you can review here
CircleCI is supported

You can try sbt-release-early.

Alternatively, the source code for sbt-ci-release is only ~50 loc, see CiReleasePlugin.scala. You can copy-paste it to project/ of your build and tweak the settings for your environment.

Does sbt-ci-release work for sbt 0.13?

Yes, but the plugin is not released for sbt 0.13. The plugin source code is a single file which you can copy-paste into project/CiReleasePlugin.scala of your 0.13 build. Make sure you also addSbtPlugin(sbt-dynver + sbt-sonatype + sbt-gpg + sbt-git).

How do I publish sbt plugins?

You can publish sbt plugins to Maven Central like a normal library, no custom setup required. It is not necessary to publish sbt plugins to Bintray.

java.io.IOException: secret key ring doesn't start with secret key tag: tag 0xffffffff

Make sure you exported the correct LONG_ID for the gpg key.
Make sure the base64 exported secret GPG key is a single line (not line wrapped). If you use the GNU coreutils base64 (default on Ubuntu), pass in the -w0 flag to disable line wrapping.

java.io.IOException: PUT operation to URL https://s01.oss.sonatype.org/content/repositories/snapshots 400: Bad Request

This error happens when you publish a non-SNAPSHOT version to the snapshot repository. If you pushed a tag, make sure the tag version number starts with v. This error can happen if you tag with the version 0.1.0 instead of v0.1.0.

java.io.IOException: Access to URL was refused by the server: Unauthorized

Make sure that SONATYPE_PASSWORD uses proper escaping if it contains special characters as documented on Travis Environment Variables.

Failed: signature-staging, failureMessage:Missing Signature:

Make sure to upgrade to the latest sbt-ci-release, which could fix this error. This failure can happen in case you push a git tag immediately after merging a branch into master. A manual workaround is to log into https://s01.oss.sonatype.org/ (or https://oss.sonatype.org/ if your Sonatype account was created before February 2021) and drop the failing repository from the web UI. Alternatively, you can run sonatypeDrop <staging-repo-id> from the sbt shell instead of using the web UI.

How do I create release notes? Can they be automatically generated?

We think that the creation of release notes should not be fully automated because commit messages don't often communicate the end user impact well. You can use Release Drafter github app (or the Github Action) to help you craft release notes.

My build suddenly fails with [info] gpg: no default secret key: No secret key

Make sure your pgp key did not expire. If it expired you have to change the expiry date and reupload it. See: https://github.com/sbt/sbt-ci-release#gpg.

Adopters

Below is a non-exhaustive list of projects using sbt-ci-release. Don't see your project? Add it in a PR!

Alternatives

There exist great alternatives to sbt-ci-release that may work better for your setup.

sbt-ci-release-early: very similar to sbt-ci-release except doesn't use SNAPSHOT versions.
sbt-release-early: additionally supports publishing to Bintray and other CI environments than Travis.
sbt-rig: additionally supporting publishing code coverage reports, managing test dependencies and publishing docs.

The biggest difference between these and sbt-ci-release wrt to publishing is the base64 encoded PGP_SECRET variable. I never managed to get the encrypted files and openssl working.