Orekit Release Guide

This release guide is largely inspired from Hipparchus Release Guide. It lists the steps that have been used in the past to release a new version of Orekit.
When in doubt, ask a question on the “Orekit development” section of the forum.

Three types of versions can be released:

Since there are some differences in the releasing process between minor/major versions and patch versions, this guide is split in two distinct sections.
The first one deals with releasing a major/minor version, while the second one is dedicated to patch versions and is mainly a list of differences between the two releasing processes.

Releasing a Major / Minor version

0. Prerequisites

SonaType OSS Account

  1. Obtain private key of the Orekit Signing Key, key id: 0802AB8C87B0B1AEC1C1C5871550FDBD6375C33B
  2. Register for account on OSSRH and associate it with the Orekit project, see: https://central.sonatype.org/pages/ossrh-guide.html

If you need help with either ask on the development section of the Orekit forum.

Once you have a SonaType OSS account, the corresponding credentials must be set in the servers section of the $HOME/.m2/settings.xml file, using an id of ossrh:

    <username>the user name to connect to the OSS site</username>
    <password>the encrypted password</password>

Use mvn -ep to generate an encrypted password.

Install Graphviz 2.38

Graphviz is used to produce the UML diagrams for the site (see /src/design/*.puml files).
Graphviz (dot) 2.39 and above put too much blank space in the generated diagrams. The bug has not yet been fixed in graphviz, so we have to use 2.38 or earlier. The version in CentOS 7 works, the version in Ubuntu 18.04 does not.

1. Verify the status of develop branch

Before anything, check on the continuous integration site that everything is fine on develop branch:

  • All tests pass;
  • Code coverage is up to the requirements;
  • There are no bugs, vulnerabilities or code smells.

If not, fix the warnings and errors first!

It is also necessary to check on the Gitlab CI/CD that everything is fine on develop branch (i.e. all stages are passed).

2. Prepare Git branch for release

Release will be performed on a dedicated branch, not directly on master or develop branch. So a new branch must be created as follows and used for everything else:

git branch release-X.Y
git checkout release-X.Y

3. Update Maven plugins versions

Release is a good opportunity to update the maven plugin versions. They are all gathered at one place, in a set of properties in orekit/pom.xml:

<!-- Project specific plugin versions -->

You can find the latest version of the plugins using the search feature at http://search.maven.org/#search. The properties name all follow the pattern orekit.some-plugin-name.version, the plugin name should be used in the web form to check for available versions.

Beware that in some cases, the latest version cannot be used due to incompatibilities. For example when a plugin was not recently updated and conflicts appear with newer versions of its dependencies.

Beware also that some plugins use configuration files that may need update too. This is typically the case with maven-checkstyle-plugin and spotbugs-maven-plugin. The /checkstyle.xml and /spotbugs-exclude-filter.xml files may need to be checked.

Before committing these changes, you have to check that everything works. So run the following command:

mvn clean
LANG=C mvn -Prelease site

If something goes wrong, either fix it by changing the plugin configuration or roll back to an earlier version of the plugin.

Browse the generated site starting at page target/site/index.html and check that everything is rendered properly.

When everything runs fine and the generated site is OK, then you can commit the changes:

git add orekit/pom.xml orekit/checkstyle.xml orekit/spotbugs-exclude-filter.xml
git commit -m "Updated maven plugins versions."

4. Updating changes.xml

Finalize the file /src/changes/changes.xml file.

The release date and description, which are often only set to TBD during development, must be set to appropriate values. The release date at this step is only a guess one or two weeks in the future, in order to take into account the 5 days release vote delay.

Replace the TBD description with a text describing the version released: state if it is a minor or major version, list the major features introduced by the version etc. (see examples in descriptions of former versions).

Commit the changes.xml file.

git add src/changes/changes.xml
git commit -m "Updated changes.xml for official release."

5. Updating documentation

Several files must be updated to take into account the new version:

file name usage required update
src/site/markdown/index.md site home page Update the text about the latest available version, including important changes from changes.xml
org/orekit/overview.html API documentation Update the text about the latest available version, including important changes from changes.xml
src/site/markdown/downloads.md.vm downloads links Declare the new versions, don't forget the date
src/site/markdown/faq.md FAQ Add line to the table of dependencies.

Once the files have been updated, commit the changes:

git add build.xml src/site/markdown/*.md
git commit -m "Updated documentation for the release."

6. Change library version number

The pom.xml file contains the version number of the library. During development, this version number has the form X.Y-SNAPSHOT. For release, the -SNAPSHOT part must be removed.

Commit the change:

git add pom.xml
git commit -m "Dropped -SNAPSHOT in version number for official release."

7. Check the JavaDoc

Depending the JDK version (Oracle, OpenJDK, etc), some JavaDoc warnings can be present. Make sure there is no JavaDoc warnings by running the following command:

mvn javadoc:javadoc

If possible, run the above command with different JDK versions.

8. Build the site

The site is generated locally using:

mvn clean
LANG=C mvn site

The official site is automatically updated on the hosting platform when work is merged into branches develop, release-* or master.

9. Tag and sign the git repository

When all previous steps have been performed, the local git repository holds the final state of the sources and build files for the release. It must be tagged and the tag must be signed. Note that before the vote is finished, the tag can only signed with a -RCx suffix to denote Release Candidate. The final tag without the -RCx suffix will be put once the vote succeeds, on the same commit (which will therefore have two tags). Tagging and signing is done using the following command, with -RCn replaced with the Release Candidate number:

git tag X.Y-RCn -s -u 0802AB8C87B0B1AEC1C1C5871550FDBD6375C33B -m "Release Candidate n for version X.Y."

The tag should be verified using command:

git tag -v X.Y-RCn

10. Pushing the branch and the tag

When the tag is ready, the branch and the tag must be pushed to Gitlab so everyone can review it:

git push --tags origin release-X.Y

Good practice: wait for the CI to succeed on the branch then release-X.Y branch on SonarQube and check that everything is fine

11. Generating signed artifacts

When these settings have been set up, generating the artifacts is done by running the following commands:

mvn deploy -DskipStagingRepositoryClose=true -Prelease

During the generation, maven will trigger gpg which will ask the user for the pass phrase to access the signing key. Maven didn’t prompt for me, so I had to add -Dgpg.passphrase=[passphrase]

Once the commands ends, log into the SonaType OSS site https://oss.sonatype.org/ and check the staging repository contains the expected artifacts with associated signatures and checksums:

  • orekit-X.Y.pom
  • orekit-X.Y.jar
  • orekit-X.Y-sources.jar
  • orekit-X.Y-javadoc.jar

The signature and checksum files have similar names with added extensions .asc, .md5 and .sha1.

Sometimes, the deployment to Sonatype OSS site also adds files with double extension .asc.md5 and .asc.sha1, which are in fact checksum files on a signature file and serve no purpose and can be deleted.

Remove orekit-X.Y.source-jar* since they are duplicates of the orekit-X.Y-sources.jar* artifacts. (We can’t figure out how to make maven stop producing these duplicate artifacts). Then click the “Close” button.

12. Calling for the vote

Everything is now ready so the developers and PMC can vote for the release. Create a post in the Orekit development category of the forum with a subject line of the form:

[VOTE] Releasing Orekit X.Y from release candidate n

and content of the form:

This is a VOTE in order to release version X.Y of the Orekit library.
Version X.Y is a maintenance release.

Highlights in the X.Y release are:
  - feature 1 description
  - feature n description

The release candidate n can be found on the GitLab repository as
tag X.Y-RCn in the release-X.Y branch:

The release notes can be read here:

Maven artifacts are available at

The votes will be tallied in 120 hours for now, on 20yy-mm-ddThh:mm:00Z
(this is UTC time).

You should also ping PMC members so they are aware of the vote. Their vote is essential for a release as per project governance.

12.1. Failed vote

If the vote fails, the maven artifacts must be removed from OSS site by dropping the repository and non-maven artifacts must be removed from the staging directory in the Orekit site. Then a new release candidate must be created, with a new number, a new tag and new artifacts. Another vote is needed for this new release candidate. So make the necessary changes and then start from the “Tag and sign the git repository” step.

12.2. Successful vote

When the vote for a release candidate succeeds, follow the steps below to publish the release.

13. Tag release version

As the vote passed, a final signed tag must be added to the succeeding release candidate, verified and pushed:

git tag X.Y -s -u 0802AB8C87B0B1AEC1C1C5871550FDBD6375C33B -m "Version X.Y."
git tag -v X.Y
git push --tags

14. Merge release branch into master

Merge the release branch into the master branch to include any changes made.

git checkout master
git merge --no-ff release-X.Y

Then commit and push.

Good practice: Again, wait for the CI to succeed and check on SonarQube that the master branch report is fine.

15. Merge master branch into develop

Merge the master branch into the develop branch to include any changes made.

git checkout develop
git merge --no-ff master

Then updated the version numbers to prepare for the next development cycle. Edit pom.xml version to SNAPSHOT and make space in the /src/changes/changes.xml file for new changes.

Then commit and push.

Good practice: Again, wait for the CI to succeed and check on SonarQube that the develop branch report is fine.

16. Publish maven artifacts

The maven artifacts must be published using OSS site to release the repository. Select the Orekit repository in “Staging Repositories” and click the “Release” button in Nexus Repository Manager.

17. Upload to Gitlab

Navigate to Projects > Orekit > Deployments > Releases and make sure the X.Y release notes looks nice.

18. Synchronize the Github mirror

To enhance the visibility of the project, a mirror is maintained on Github. The releases created on Gitlab are not automatically pushed on this mirror. They have to be declared manually to make visible the vitality of Orekit.

  1. Login to Github
  2. Go to the Orekit releases page
  3. Click on the Draft a new release button
  4. In the “Tag version” field of the form and in the “Release title” field, enter the tag of the release to be declared
  5. Describe the release as it has been done on Gitlab
  6. Click on “Publish release”

Github automically adds two assets (zip and tarball archives of the tagged source code)

19. Update Orekit site

Several edits need to be done to the Orekit website after the vote.

First, clone the current code:

git clone https://gitlab.orekit.org/orekit/website-2015

Switch to develop branch. Edit overview.html:

  • (If needed) Update the new Hipparchus version.
  • Update the overview.png image with the new version numbers.
  • (If needed) Update the Features section with the new features added by the new version of Orekit.

Create a new post for the release in _post/, it will be visible in the News page (see section Announce Release for the content of the post).

Push the modifications on develop branch, wait until the pipeline on Gitlab is finished, then the test website will be updated.

Check that everything looks nice and then merge develop on master branch and push the modifications.
When the Gitlab pipeline is finished, the official website should be updated according to your changes.

20. Close X.Y milestone

In Gitlab, navigate to Projects > Orekit > Issues > Milestones. Click “Close Milestone” for the line corresponding to the release X.Y.

21. Announce release

The last step is to announce the release by creating a post in the Orekit announcements category of the forum with a subject line of the form:

Orekit X.Y released

and content of the form:

The Orekit team is pleased to announce the release of Orekit version X.Y.
This is a minor/major version, including both new features and bug fixes.
The main changes are:

  - feature 1 description
  - feature n description

This version depends on Hipparchus X'.Y'

For complete release notes please see:

The maven artifacts are available in maven central. 
The source and binaries can be retrieved from the forge releases page:

Releasing a Patch version

Here the main difference are that:

  • We're going to use a former release branch to do the release;
  • A vote of the PMC is not required to release the version.

If we're releasing patch version X.Y.Z, then we're going to use the already existing release-X.Y branch on the repository to do the release.

  • X: Major version number
  • Y: Minor version number
  • Z: Patch version number

Once again, a patch version should only contain bug fixes that do not break APIs !

0. Prerequisites

Prerequisites are the same as for a minor/major version.

1.1 Verify the status of the already existing release branch

Here we will run the same checks than for a minor/major version but on the release-X.Y branch instead of the develop branch.
See above for the checks (SonarQube: tests, code coverage, code quality / Gitlab CI/CD: all stages passed succesfully).

One could argue that the release-X.Y branch should always be in a clean state since it contains the latest release.
However, for patches purpose, developers may have merged bug corrections on the release-X.Y branch since the last release.

1.2 Verify the status of the remaining opened merge requests

Here we are going to verify the status of each still-opened merge request (MR) that is in the scope of the version.

Start from the milestone of the version, note the issues in the scope that are not closed, and find the associated MR.

Then, for each MR:

  • Check that the pipeline was a success (i.e. all stages passed)
  • If it exists, find the SonarQube report for the MR, either in a short-lived branch of Orekit main CI report or on the developer own sub-project on SonarQube.
    Check that:
    • All tests pass;
    • Code coverage is up to the requirements;
    • There are no bugs, vulnerabilities or code smells.

If not, ask for a fix of the warnings and errors first!

2. Prepare Git branch for release

The patch release will be performed on previous release branch.

So first, check out the dedicated branch:

git checkout release-X.Y

Then, merge all the merge requests (MR) in the scope of the version in branch release-X.Y.

There are two cases here, they are detailed in the two points below.

2.1. Merging the remaining merge requests

If the developer made his changes starting from branch release-X.Y, you can simply merge the branch of the MR in branch release-X.Y.

Note that if there aren't any conflict in Gitlab you can directly do the merge from Gitlab; just make sure that the target branch is release-X.Y and not “develop”.

Find the MR on the repository, it should be in branch origin/merge-requests/XXX with XXX the number of the MR

git merge --no-ff origin/merge-requests/XXX

The --no-ff option will force a merge commit to be made, instead of doing a fast-forward on the branch.
You can keep the automatic merge message unless you want to add some content to it.

Eventually, resolve any conflict and commit the result.

2.2. Cherry-picking the commits

If the developer started from develop branch (or any other branch), then the MR branch may contain code that should not be added to the release.
You will have to cherry-pick the appropriate commits and add them to a dedicated branch.
It is advised to use an IDE to do the cherry-picking although the command lines below will help you.

Find the MR on the repository and the commits you are interested in.

Create a dedicated branch for the issue on your local repository:

git checkout -b issue-YYY

Where YYY is the number of the issue that the MR XXX fixes.
If the branch already exists, give it a different name like integrate-issue-YYY or integrate-MR-XXX

Make a list of the IDs of the commits you want to add, example A B C D (in the order they were committed).

Cherry-pick the commits in a chronological order:

git cherry-pick A B C D

Eventually, resolve any conflict and commit the result.

Return to the release branch and merge the branch issue-YYY:

git checkout release-X.Y
git merge --no-ff issue-YYY

3. Update Maven plugins versions

Skip this for a patch version.

4. Update changes.xml

Do the same as for a minor/major version.

5. Updating documentation

Do the same as for a minor/major version.

6. Change library version number

The pom.xml file contains the version number of the library.
On the release-X.Y branch, the version number should be X.Y or X.Y.Z if a patch was already released for this version.

Replace version number from X.Y to X.Y.1 or X.Y.Z to X.Y.Z+1

Commit the change:

git add pom.xml
git commit -m "Increment version number for patch release."

Steps 7 to 11

Do the same as for a minor/major version.

12. Calling for the vote

Skip this for a patch version.

As per Orekit governance rules, a vote of the PMC is not required for a patch version.

Steps 13 to 21

Do the same as for a minor/major version.