Hi Apache KIE community,

Long-time contributors know how time‑consuming it can be to upgrade
Kogito's required frameworks, such as Quarkus and Spring Boot. This
activity is both critical and recurring, yet based on our experience it
often requires a significant and unpredictable amount of effort.

Given how frequently we need to perform these upgrades, we believe it's
time to improve the process. We would like to propose a set of changes to
the current BOM management approach, based on lessons learned from past
upgrades across the KIE ecosystem.

We welcome any opinions and feedback from the community. To better
understand the proposed changes, please review the draft PRs that
demonstrate the implementation. We encourage discussion and collaboration
on these PRs to refine the approach. For tracking and coordination, please
refer to the main issue:
https://github.com/apache/incubator-kie-issues/issues/2029. Here, you can
find the open PRs ready to be reviewed.

The goal of this initiative is to:

   - reduce the overall time spent on framework upgrades,
   - make the process more predictable and consistent,
   - enable both current and future maintainers to complete these tasks in
   days rather than weeks,
   - allow each framework to be upgraded independently, without worrying
   about transitive dependency conflicts,
   - apply CVE fixes faster without cross-framework coordination.

The proposed changes will impact the following repos:

   - drools
   - kogito-runtimes
   - kogito-apps
   - kogito-examples
   - kie-tools

Current Status of BOM Management

drools:

   - build-parent/pom.xml: This module currently acts as the main BOM,
   managing both the third-party dependencies and the internal dependency
   declarations. It also defines Quarkus (and likely several Quarkus‑related
   dependencies). Three main issues have been identified:
      1. Framework coupling: The drools repo should be "cloud-native
      framework agnostic"; Quarkus and related specific dependencies should not
      be declared here.
      2. Mixed responsibility inside the BOM: Internal project dependencies
      and external third‑party dependencies are currently managed
within the same
      BOM. This makes version alignment, troubleshooting, and
framework upgrades
      harder to reason about, and increases the risk of unintended side effects
      during dependency updates.
      3. Scattered dependency declarations across submodules: Not all
      third‑party dependencies are declared in the main BOM; some are managed
      directly within individual submodules. This fragmentation makes it more
      difficult to track, align, and update dependencies consistently
across the
      codebase.

kogito-runtimes:

   - kogito-dependencies-bom/pom.xml: Acts as the main BOM for Kogito
   runtime projects, declaring third‑party dependencies required for
   cloud‑native applications (e.g. Quarkus, Spring Boot, and related
   libraries).
   - kogito-quarkus-bom/pom.xml: Intended to manage third‑party
   dependencies specific to Quarkus‑based Kogito applications.
   - kogito-spring-boot-bom/pom.xml: Intended to manage third‑party
   dependencies specific to Spring Boot‑based Kogito applications.

Main issues identified:

   1. Unused framework‑specific BOMs: Despite the presence of both
   kogito-quarkus-bom and kogito-spring-boot-bom, which are intended to
   manage Quarkus and Spring Boot dependencies respectively, these BOMs are
   effectively empty and not used for their intended scope. As a result,
   framework‑specific dependencies are still being managed elsewhere,
   defeating the purpose of having dedicated BOMs.
   2. Duplication of third‑party dependency declarations: A significant
   portion of the third‑party dependencies declared in kogito-dependencies-bom
   duplicates dependencies already declared in drools/build-parent/pom.xml.
   This duplication is unnecessary and increases the risk of: version
   misalignment, dependency conflicts, higher maintenance costs (e.g. CVE
   fixes and coordinated upgrades).

kogito-apps: The kogito-apps repository does not currently define its own
BOM to manage third-party dependencies. However, the existing project
structure limits the ability to take advantage of the framework‑specific
BOM split already present in the kogito-runtimes repository.

The applications are organized by feature rather than by framework, using
the following structure:

kogito-apps/feature+ common-impl+ quarkus-impl+ spring-boot-impl

kie-tools: This repository has a Maven module acting as a BOM, maven-base.
It already imports kogito-apps-bom, together with additional unnecessary
KIE BOMs. As a result, Quarkus-specific dependencies are mixed into a
shared dependency management layer.
Problems to Solve

   - The same dependency is declared with different versions in "parent"
   and "children" modules
   - The same dependency is inherited transitively in some modules but
   explicitly declared in others
   - At the bottom of the stack (final applications/examples) there are
   multiple convergence issues
   - Wrong behavior often appears at runtime rather than compile time,
   making it hard to detect

Proposed Changes

drools:

   - Introduce a new kie-parent/pom.xml BOM: A new kie-parent module will
   be introduced as the only place where third-party dependencies are
   declared. This BOM will be used throughout the KIE ecosystem. All
   identified Quarkus‑related dependencies will be excluded from this BOM,
   keeping it framework agnostic.
   - Introduce a new kie-parent-drools/pom.xml BOM: A new
kie-parent-drools module
   will be introduced as a BOM aggregator for first-party Drools dependencies
   (internal Drools modules). This separates first-party dependency management
   from third-party dependencies in kie-parent.
   - Refocus drools-build-parent/pom.xml responsibilities: The existing
   drools-build-parent/pom.xml will be refocused to keep build
   configuration and plugin management only. It will no longer manage
   first-party dependencies (moved to kie-parent-drools) and will no longer
   declare third-party dependencies directly. It will inherit from
   kie-parent-drools.
   - Remove all <dependencyManagement> from submodules: All submodules will
   inherit dependency versions from kie-parent, with no local overrides
   allowed.
   - Enforce centralized dependency management: Two new enforcer rule
   modules will be introduced:
      - kie-no-dependency-management-enforcer-rule: Enforces a "no
      dependencyManagement" rule within Drools submodules. Submodules will
      no longer be allowed to declare their own <dependencyManagement>
sections,
      not even inside profiles. This prevents the anti‑pattern of declaring
      dependency versions outside the main BOM. Exceptions will be allowed only
      for well‑justified and explicitly approved cases via the
      <allowedPomsList> property.
      - kie-no-external-managed-dependency-enforcer-rule: Blocks dependency
      management entries for external artifacts not part of the current
      multi-module project. This keeps managed dependencies limited to the
      project's own modules and prevents accidentally pulling in or controlling
      versions of unrelated external libraries.
   - Isolate Quarkus‑specific build logic: A new module,
   kie-quarkus-build-parent, will be introduced to extend kie-parent for
   the only allowed Quarkus‑related module within Drools (
   drools-quarkus-extension). This exception is retained for historical
   reasons (Drools has a dependency on Quarkus). It extends rather than
   imports to also inherit pluginManagement.

See diagram:
https://github.com/user-attachments/assets/7db5e9be-213d-4d86-804f-e1f1cffb50d3

kogito-runtimes:

   - Remove kogito-dependencies-bom: Deleted as it's no longer needed;
   functionality replaced by inheriting directly from drools/kie-parent through
   the parent hierarchy, eliminating duplication of third-party dependency
   declarations.
   - Modify kogito-bom: Existing BOM module, now inherits from
   drools/kie-parent-drools, aggregating kogito-specific dependency
   management.
   - Modify kogito-runtime-bom: Existing runtime BOM, now inherits from
   drools-build-parent for configuration build setting import.
   - Modify kie-kogito-bom: Existing KIE-Kogito integration BOM, now
   inherits from drools-build-parent.
   - Populate kogito-quarkus-bom: Existing but previously unused BOM now
   populated with all Quarkus-specific dependencies; inherits from
   kogito-build-no-bom-parent; inherited by kogito-apps-quarkus.
   - Populate kogito-spring-boot-bom: Existing but previously unused BOM
   now populated with all Spring Boot-specific dependencies; inherits from
   kogito-build-no-bom-parent; inherited by kogito-apps-spring-boot.
   - Remove all <dependencyManagement> from submodules: All submodules
   inherit dependency versions from their parent BOMs.
   - Uniform checks with drools repository: Apply the same enforcer rules
   and patterns used in drools.

See diagram:
https://github.com/user-attachments/assets/90f80d70-2300-4d8a-901a-330807039440

kogito-apps:

   - Regroup applications by framework instead of by feature: The current
   feature‑centric structure will be reorganized to be framework‑centric.
   Specifically, two top‑level, framework‑specific modules will be introduced:
   kogito-apps-quarkus and kogito-apps-spring-boot. All framework‑specific
   application modules will be moved under their respective top‑level
   framework module.

See diagram:
https://github.com/apache/incubator-kie-issues/issues/2029#kogito-apps-diagram

kogito-examples: The kogito-examples repository will receive only minimal
changes required to work with the main changes applied in upstream
repositories. The main changes are: the POM file of the Quarkus examples
module will import the kogito-apps-quarkus-bom BOM and the Spring Boot
examples module will import the kogito-apps-spring-boot-bom BOM.

kie-tools:

   - Keep maven-base as the shared base BOM, but clean it up by removing
   unnecessary dependencies and BOM imports already covered by kie-parent
    (drools).
   - Create maven-quarkus-bom and maven-spring-boot-bom to manage Quarkus
   and Spring Boot dependencies separately.
   - Make leaf modules inherit from the appropriate framework-specific BOM
   according to their runtime framework.

See diagram:
https://github.com/user-attachments/assets/06f8362a-092d-40bb-8a01-3560c41a4a8e
Kudos to Gabriele Cardosi, who is driving this important initiative
and to Chinchu
P Shaji for her support.

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