This is based on the release guide of the Apache Beam project: https://beam.apache.org/contribute/release-guide/

Introduction

The Apache Flink project periodically declares and publishes releases. A release is one or more packages of the project artifact(s) that are approved for general public distribution and use. They may come with various degrees of caveat regarding their perceived quality and potential for change, such as “alpha”, “beta”, “incubating”, “stable”, etc.

The Flink community treats releases with great importance. They are a public face of the project and most users interact with the project only through the releases. Releases are signed off by the entire Flink community in a public vote.

Each release is executed by a Release Manager, who is selected among the Flink PMC members. This document describes the process that the Release Manager follows to perform a release. Any changes to this process should be discussed and adopted on the dev@ mailing list.

Please remember that publishing software has legal consequences. This guide complements the foundation-wide Product Release Policy and Release Distribution Policy.

Overview


The release process consists of several steps:

  1. Decide to release
  2. Prepare for the release
  3. Build a release candidate
  4. Vote on the release candidate
  5. If necessary, fix any issues and go back to step 3.
  6. Finalize the release
  7. Promote the release

Decide to release

Deciding to release and selecting a Release Manager is the first step of the release process. This is a consensus-based decision of the entire community.

Anybody can propose a release on the dev@ mailing list, giving a solid argument and nominating a committer as the Release Manager (including themselves). There’s no formal process, no vote requirements, and no timing requirements. Any objections should be resolved by consensus before starting the release.

In general, the community prefers to have a rotating set of 3-5 Release Managers. Keeping a small core set of managers allows enough people to build expertise in this area and improve processes over time, without Release Managers needing to re-learn the processes for each release. That said, if you are a committer interested in serving the community in this way, please reach out to the community on the dev@ mailing list.

Checklist to proceed to the next step

  1. Community agrees to release
  2. Community selects a Release Manager

Prepare for the release

Before your first release, you should perform one-time configuration steps. This will set up your security keys for signing the release and access to various release repositories.

To prepare for each release, you should audit the project status in the JIRA issue tracker, and do necessary bookkeeping.

One-time setup instructions

GPG Key

You need to have a GPG key to sign the release artifacts. Please be aware of the ASF-wide release signing guidelines. If you don’t have a GPG key associated with your Apache account, please create one according to the guidelines.

Determine your Apache GPG Key and Key ID, as follows:

gpg --list-keys
This will list your GPG keys. One of these should reflect your Apache account, for example:
--------------------------------------------------
pub   2048R/845E6689 2016-02-23
uid                  Nomen Nescio <anonymous@apache.org>
sub   2048R/BA4D50BE 2016-02-23

Here, the key ID is the 8-digit hex string in the pub line: 845E6689.

Now, add your Apache GPG key to the Flink’s KEYS file in release repository at dist.apache.org. Follow the instructions listed at the top of these files. (Note: Only PMC members have write access to the release repository. If you end up getting 403 errors ask on the mailing list for assistance.)  PMC member can refer following scripts to add your Apache GPG key to the KEYS in the release repository.

svn co https://dist.apache.org/repos/dist/release/flink flink-dist-release-repo
cd flink-dist-release-repo
(gpg --list-sigs <YOUR_KEY_ID> && gpg --armor --export <YOUR_KEY_ID>) >> KEYS
svn ci -m "[flink] Add <YOUR_NAME>'s public key"

Configure git to use this key when signing code by giving it your key ID, as follows:

git config --global user.signingkey 845E6689

You may drop the --global option if you’d prefer to use this key for the current repository only.

You may wish to start gpg-agent to unlock your GPG key only once using your passphrase. Otherwise, you may need to enter this passphrase hundreds of times. The setup for gpg-agent varies based on operating system, but may be something like this:

eval $(gpg-agent --daemon --no-grab --write-env-file $HOME/.gpg-agent-info)
export GPG_TTY=$(tty)
export GPG_AGENT_INFO

Access to Apache Nexus repository

Configure access to the Apache Nexus repository, which enables final deployment of releases to the Maven Central Repository.

  1. You log in with your Apache account.
  2. Confirm you have appropriate access by finding org.apache.flink under Staging Profiles.
  3. Navigate to your Profile (top right dropdown menu of the page).
  4. Choose User Token from the dropdown, then click Access User Token. Copy a snippet of the Maven XML configuration block.

  5. Insert this snippet twice into your global Maven settings.xml file, typically ${HOME}/.m2/settings.xml. The end result should look like this, where TOKEN_NAME and TOKEN_PASSWORDare your secret tokens:

    settings.xml
    <settings>
   <servers>
     <server>
       <id>apache.releases.https</id>
       <username>TOKEN_NAME</username>
       <password>TOKEN_PASSWORD</password>
     </server>
     <server>
       <id>apache.snapshots.https</id>
       <username>TOKEN_NAME</username>
       <password>TOKEN_PASSWORD</password>
     </server>
   </servers>
 </settings>

Verify that a Release Build Works

Run mvn -Prelease clean install to ensure that the build processes that are specific to that profile are in good shape.

Checklist to proceed to the next step

  1. Release Manager’s GPG key is published to dist.apache.org
  2. Release Manager has org.apache.flink listed under Staging Profiles in Nexus
  3. Release Manager’s Nexus User Token is configured in settings.xml

Build a release candidate

The core of the release process is the build-vote-fix cycle. Each cycle produces one release candidate. The Release Manager repeats this cycle until the community approves one release candidate, which is then finalized.

The following sections assume that the release_utils branch from flink-connector-shared-utils is mounted as a git submodule under tools/releasing/shared, you can update the submodule by running  git submodule update --remote (or git submodule update --init --recursive if the submodule wasn't initialized, yet) to use latest release utils, you need to mount the  flink-connector-shared-utils  as a submodule under the tools/releasing/shared if it hasn't been mounted in the connector repository. See the README for details.

Prepare environment

Check out the commit from which you intend to create the release, and run these commands in the root directory of the connector repo:

# Set up a few environment variables to simplify Maven commands that follow.
# (We use bash Unix syntax in this guide.)
export NEW_VERSION=3.0.0
export RC_NUM=1
export PROJECT=flink-connector-<project>
export REMOTE=origin
export MAVEN_SKIP_RC=false
export MAVEN_OPTS=""
export MAVEN_CONFIG=""
export MAVEN_DEBUG_OPTS=""

If you are releasing flink-connector-parent, you need to define an extra $PROJECT variable so that the artifacts are not named after the project directory which is flink-connector-shared-utils:

export PROJECT=flink-connector-parent

Create and stage source release

We now need to do several things:

  • Prepare the code base (update the version, create and push a git tag)
  • Create the source release archive and deploy it to dist.apache.org


# verify the environment contains all software needed for the release process
./tools/releasing/shared/check_environment.sh

# update the versions in the poms
./tools/releasing/shared/update_branch_version.sh

# create and stage artifacts to be voted on
./tools/releasing/shared/release_git_tag.sh
./tools/releasing/shared/stage_source_release.sh

Create and stage jars

We now need to build and deploy jar artifacts to the Apache Nexus Repository, which is the staging area for deploying the jars to Maven Central

Note: Please do not use VPN or change your IP address when stage artifacts to Apache Nexus Repository, it may lead to multiple staging repositories which is unexpected.

Regular connector release case

For regular connector release, there is a jar per supported Flink version:

# call this once for each supported (minor) Flink version
FLINK_VERSION=1.16.0 FLINK_MINOR_VERSION=1.16 ./tools/releasing/shared/stage_jars.sh

For flink-connector-parent release, there is no notion of supported Flink version, there is one single artifact:

# run only once
./tools/releasing/shared/stage_jars.sh

Review all staged artifacts

Close the staging repository on Apache Nexus.

Review Release Notes in JIRA

JIRA automatically generates Release Notes based on the Fix Version field applied to issues. Release Notes are intended for Flink users (not Flink committers/contributors). You should ensure that Release Notes are informative and useful.

Open the release notes from the version status page by choosing the release underway and clicking Release Notes.

You should verify that the issues listed automatically by JIRA are appropriate to appear in the Release Notes. Specifically, issues should:

  • Be appropriately classified as Bug, New Feature, Improvement, etc.
  • Represent noteworthy user-facing changes, such as new functionality, backward-incompatible API changes, or performance improvements.
  • Have occurred since the previous release; an issue that was introduced and fixed between releases should not appear in the Release Notes.
  • Have an issue title that makes sense when read on its own.

Adjust any of the above properties to the improve clarity and presentation of the Release Notes.

Content of Release Notes field from JIRA tickets 

To get the list of "release notes" field from JIRA, you can ran the following script using JIRA REST API (notes the maxResults limits the number of entries):

curl -s https://issues.apache.org/jira//rest/api/2/search?maxResults=200&jql=project%20%3D%20FLINK%20AND%20%22Release%20Note%22%20is%20not%20EMPTY%20and%20fixVersion%20%3D%20${RELEASE_VERSION} | jq '.issues[]|.key,.fields.summary,.fields.customfield_12310192' | paste - - -

jq  is present in most Linux distributions and on MacOS can be installed via brew.

Propose a pull request for website updates

The final step of building the candidate is to propose a website pull request.

The flink_connectors.yml must be updated to contain the new release.

Finally, propose a pull request with these changes. (Don’t merge before finalizing the release.)

Checklist to proceed to the next step

  1. Maven artifacts deployed to the staging repository of repository.apache.org
  2. Source distribution deployed to the dev repository of dist.apache.org
  3. Website pull request proposed to list the release

Vote on the release candidate

Once you have built and individually reviewed the release candidate, please share it for the community-wide review. Please review foundation-wide voting guidelines for more information.

Start the review-and-vote thread on the dev@ mailing list. Here’s an email template; please adjust as you see fit.

echo "
 
From: Release Manager
To: dev@flink.apache.org
Subject: [VOTE] Release ${PROJECT:-flink-connector-<connector>} v${NEW_VERSION}, release candidate #${RC_NUM}
Content:
 
Hi everyone,
Please review and vote on release candidate #${RC_NUM} for ${PROJECT:-flink-connector-<connector>} v${NEW_VERSION}, as follows:
[ ] +1, Approve the release
[ ] -1, Do not approve the release (please provide specific comments)
 
 
The complete staging area is available for your review, which includes:
* JIRA release notes [1],
* the official Apache source release to be deployed to dist.apache.org [2], which are signed with the key with fingerprint $(git config user.signingKey) [3],
* all artifacts to be deployed to the Maven Central Repository [4],
* source code tag v${NEW_VERSION}-rc${RC_NUM} [5],
* website pull request listing the new release [6].
* CI build of the tag [7].
 
The vote will be open for at least 72 hours. It is adopted by majority approval, with at least 3 PMC affirmative votes.
 
Thanks,
Release Manager
 
[1] link
[2] https://dist.apache.org/repos/dist/dev/flink/${PROJECT:-flink-connector-<connector>}-${NEW_VERSION}-rc${RC_NUM}
[3] https://dist.apache.org/repos/dist/release/flink/KEYS
[4] link
[5] https://github.com/apache/${PROJECT:-flink-connector-<connector>}/releases/tag/v${NEW_VERSION}-rc${RC_NUM}
[6] link
[7] link
"

If there are any issues found in the release candidate, reply on the vote thread to cancel the vote. There’s no need to wait 72 hours. Proceed to the Fix Issues step below and address the problem. However, some issues don’t require cancellation.

If there are no issues, reply on the vote thread to close the voting. Then, tally the votes in a separate email. Here’s an email template; please adjust as you see fit.

echo "

From: Release Manager
To: dev@flink.apache.org
Subject: [RESULT] [VOTE] flink-connector-<connector> ${NEW_VERSION}, release candidate #${RC_NUM}

I'm happy to announce that we have unanimously approved this release.

There are XXX approving votes, XXX of which are binding:
* approver 1
* approver 2
* approver 3
* approver 4

There are no disapproving votes.

Thanks everyone!
"

Checklist to proceed to the finalization step

  1. Community votes to release the proposed candidate, with at least three approving PMC votes

Fix any issues

Any issues identified during the community review and vote should be fixed in this step.

Code changes should be proposed as standard pull requests to the master branch and reviewed using the normal contributing process. Then, relevant changes should be cherry-picked into the release branch. The cherry-pick commits should then be proposed as the pull requests against the release branch, again reviewed and merged using the normal contributing process.

Once all issues have been resolved, you should go back and build a new release candidate with these changes.

Checklist to proceed to the next step

  1. Issues identified during vote have been resolved, with fixes committed to the release branch.

Finalize the release

Once the release candidate has been reviewed and approved by the community, the release should be finalized.

Deploy artifacts to Maven Central Repository

Use the Apache Nexus repository to release the staged binary artifacts to the Maven Central repository. In the Staging Repositories section, find the relevant release candidate orgapacheflink-XXX entry and click Release. Drop all other release candidates that are not being released.

Deploy source and binary releases to dist.apache.org

Copy the source and binary releases from the dev repository to the release repository at dist.apache.org.

PROJECT=flink-connector-<connector> VERSION=${NEW_VERSION} RC_NUM=<rc> ./tools/releasing/shared/release_source_release.sh

Git tag

Create a new Git tag for the released version by copying the tag for the final release candidate, as follows

export RC_NUM=none
./tools/releasing/shared/release_git_tag.sh

Mark the version as released in JIRA

In JIRA, inside version management, hover over the current release and a settings menu will appear. Click Release, and select today’s date.

flink-connector-parent is just a pom.xml file with no dedicated documentation page, so this section does not apply to flink-connector-parent release


  1. Make sure that in the correct Flink release branch (e.g. release-1.19, release-1.18 etc) in https://github.com/apache/flink/blob/master/docs/setup_docs.sh#L45-L57 there's a line that shows:

    integrate_connector_docs yourConnectorRepoName yourReleasedConnectorBranch

    When the documentation is being build, it will also download the documentation from the connector repository from the specified branch, so that it will be integrated into the Flink documentation

  2. Make sure that the file in docs/data/yourConnector.yml is been updated properly (correct connector version, correct compatibility with Flink major.minor version, potential SQL variants). See https://github.com/apache/flink-connector-kafka/blob/v3.0/docs/data/kafka.yml as an example. This file is being used to determine if the Flink documentation is requested for a released Flink version, if it should display the download link for your connector (because it was released/available) or not (e.g. it's not available yet for that Flink version)
flink-connector-parent is just a pom.xml file with only a simple "mvn install" git workflow, so this section does not apply to flink-connector-parent release

Update .github/workflows/weekly.yml in the main  branch for the connector repository to make sure that:

  1. Any potentially newly created branch is also tested in the weekly test and mapped to the Flink versions that it should be tested against
  2. Remove any no longer supported connector branches and/or Flink versions

Checklist to proceed to the next step

  • Maven artifacts released and indexed in the Maven Central Repository
  • Source distribution available in the release repository of dist.apache.org
  • Source distribution removed from the dev repository of dist.apache.org
  • Release tagged in the source code repository
  • Release version finalized in JIRA. (Note: Not all committers have administrator access to JIRA. If you end up getting permissions errors ask on the mailing list for assistance.)

Promote the release

Once the release has been finalized, the last step of the process is to promote the release within the project and beyond. Please wait for 24h after finalizing the release in accordance with the ASF release policy.

Merge website pull request

Merge the website pull request to list the release. Make sure to regenerate the website as well, as it isn't built automatically.

Apache mailing lists

Announce on the dev@ mailing list that the release has been finished.

Make sure that you send this email using text MIME Content-Type otherwise ASF mail servers will refuse to send it to announce@apache.org

echo "

From: Release Manager
To: announce@apache.org, user@flink.apache.org, dev@flink.apache.org
Reply-To: user@flink.apache.org
Subject: [ANNOUNCE] Apache flink-connector-<connector> ${NEW_VERSION} released

The Apache Flink community is very happy to announce the release of Apache flink-connector-<connector> ${NEW_VERSION}. 

Apache Flink® is an open-source stream processing framework for distributed, high-performing, always-available, and accurate data streaming applications.

The release is available for download at:
https://flink.apache.org/downloads.html
 
The full release notes are available in Jira:
<jira release notes link>
 
We would like to thank all contributors of the Apache Flink community who made this release possible!
 
Regards,
Release Manager
"

Recordkeeping

Use reporter.apache.org to seed the information about the release into future project reports.

Checklist to declare the process completed

  1. Website pull request to list the release merged
  2. Release recorded in reporter.apache.org.
  3. Release announced on the dev@ mailing list.

Improve the process

It is important that we improve the release processes over time. Once you’ve finished the release, please take a step back and look what areas of this process can be improved. Perhaps some part of the process can be simplified. Perhaps parts of this guide can be clarified.

If we have specific ideas, please start a discussion on the dev@ mailing list and/or propose a pull request to update this guide. Thanks!