Howdy,
some tooling already exists:
gav-dm-tree:
https://gist.github.com/cstamas/7e3f8d444a74d9a2f4f7d7114af156bf
gav-dm-list
<https://gist.github.com/cstamas/7e3f8d444a74d9a2f4f7d7114af156bfgav-dm-list>:
https://gist.github.com/cstamas/419f4663744150b76f737cbd89fedf4f
and the new "flatten bom" mojo.
And my proposal is to "pre-digest" the BOM, not any BOM you consume,
just those super-BOMs that have deep (import) hierarchy (look at
dm-tree and dm-list outputs above).
While I did flatten-BOM, I was also tinkering to do some "merge" or
alike, but realized that:
* simple tool is better than complex
* flatten "solves" the problem for big BOMs (for example, using this
tool for Junit BOM makes no sense)
* the rest of how to "fit" flattened BOM becomes simpler, as now that
they are flat, you DO have control.
* generation of flat BOM should be consistent: for same BOM GAV the
output should be SAME -- just keep it simple; if we add knobs like
which version to select, user could easily shoot himself in the foot
The goal of new mojo is to flatten input BOM and do it consistently:
if you point it at same BOM, your output is same as before (sans
possible coordinate change of the emitted BOM itself)
T
On Wed, Mar 19, 2025 at 9:16 AM Hervé Boutemy <hbout...@apache.org> wrote:
FTR Jira issues
https://issues.apache.org/jira/browse/MNG-7906
https://issues.apache.org/jira/browse/MNG-7854
https://issues.apache.org/jira/browse/MPH-183
and all linked issues
I don't know how this is relates with bom packaging in Maven 4
https://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html#Bill_of_Materials_.28BOM.29_POMs
The fact that this dependencyManagement import happens at effective model
building stage, and not during dependency resolution, created specific
complexity on how to analyze conflict resolution, report (not possible to
dependency-tree -Dverbose), and have solutions for end-user to override
default conflict resolution result.
I dislike the currently non-actionable WARNINGs, particularly when
actionable
solution when a conflict resolution does not bring you the result you
want, you
can override by declaring a dependencyManagement entry before import.
On what conflict resolution algorithm is in place, should we change it,
to
which one: discussion never went to a solid proposition.
Notice that we don't have great usable documentation on that feature and
its
problems: just long discussions in Jira issues.
I discover here what I'll call a new proposal from Tamasz:
1. promote avoiding multiple conflicting dependencyManagement imports,
as they
are hard to analyze
2. promote a merging tool where these conflicts can be worked on and
choices
done: first wins? last wins? (personal addition) greater wins?
I'm sure some reporting on BOM POMs could also be interesting, given they
started small and easy to get when used individually, but went complex
when
people started to assemble them
HTH
Hervé
Le mardi 18 mars 2025, 18:47:49 CET Tamás Cservenák a écrit :
Howdy,
Problem with BOM imports is that they were never "done done" in Maven
3.x time-frame, and they work the total opposite to everything else in
Maven (think dependencies, as Delany says), hence they work in "non
Maven way", not intuitive way, and tend to cause (usually bad)
surprises. Sadly, they are overused in many projects, especially with
recursive-imports happening. Maven 4 just tries to warn you about
these, when a dependency is "stepping on toe" of another dependency,
but again, as a consumer, you have not much control over it.
Personally, I'd avoid using BOMs like these, and I'd preferably
generate my own.
In short, BOMs should be
* flat (no recursive import)
* generated
* curated
Sadly, with BOM you point at, none of these stands. Maven 4 tries to
"fix" things, that's all. Same as with CI Friendly support, this is
just yet another "incomplete" implementation.
Personally, I'd prevent or better REMOVE recursive import capability
(so dep type=pom scope=import would NOT recursively import anything)
-- just to force them to be flat for start.
BOMs should be curated and generated (and flat).
For these cases:
* take a peek at BOM generator (used in Maven build as well):
https://github.com/maveniverse/bom-builder-maven-plugin
* took a stab for a tool I'd use: BOM flatten, try it
out!https://github.com/maveniverse/toolbox/pull/180
Regarding flatten-BOM: again, perso I'd NOT use BOM specified by you,
but instead I'd deploy "flattened" BOM under my namespace (see gist
example) and use that. Given it is generated, you can just generate
new for any new version out there,
My 5 cents
T
On Mon, Mar 17, 2025 at 8:43 PM Karl Heinz Marbaise
<khmarba...@gmx.de.invalid> wrote:
Hi to all,
currently I'm trying to build a simple spring boot application which
uses a BOM for spring-boot-dependencies..
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>3.3.3</version>
<scope>import</scope>
<type>pom</type>
</dependency>
So based on the releases of JUnit Jupiter, Mockito etc.
I define the BOM's of JUnit Jupiter and Mockito (and others; only
excerpts shown here) before the spring boot dependencies like this,
because I want to use newer versions, than spring-boot-dependencies
defines.>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.junit</groupId>
<artifactId>junit-bom</artifactId>
<version>5.12.1</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-bom</artifactId>
<version>5.16.1</version>
<scope>import</scope>
<type>pom</type>
</dependency>
..
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>${spring.boot.version}</version>
<scope>import</scope>
<type>pom</type>
</dependency>
..
</dependencies>
</dependencyManagement>
If I build the project Maven 4.0.0-rc3 I got a bunch of warnings like
this:
mvn clean -e
[INFO] Error stacktraces are turned on.
[INFO]
.....
[INFO] Scanning for projects...
[WARNING]
[WARNING] 26 problems were encountered while building the effective
model for 'com.soebes.spring.example:employee:jar:0.0.1-SNAPSHOT'
(use
-e to see details)
[WARNING] Ignored POM import for:
org.assertj:assertj-core:jar:3.25.3@compile as already imported
org.assertj:assertj-core:jar:3.27.3@compile. Add the conflicting
managed
dependency directly to the dependencyManagement section of the POM.
[WARNING] Ignored POM import for:
org.assertj:assertj-guava:jar:3.25.3@compile as already imported
org.assertj:assertj-guava:jar:3.27.3@compile. Add the conflicting
managed dependency directly to the dependencyManagement section of
the
POM.
[WARNING] Ignored POM import for:
org.junit.jupiter:junit-jupiter:jar:5.10.3@compile as already
imported
org.junit.jupiter:junit-jupiter:jar:5.12.1@compile. Add the
conflicting
managed dependency directly to the dependencyManagement section of
the
POM....
In Maven 3.9.9 I can build that project without any warning, because
the
junit-bom is defined before the spring-boot-dependencies (which has
junit-bom on it's own in an older version), but overwrites the
defined
in the spring-boot-dependencies with the newer versions, which is
exactly what I want..
Back to Maven 4:
So does that mean I have to add all the deps which are coming from
the
junit-bom (also for the deps from assertj-bom, mockito-bom etc.)
manually into my dependencyManagement, as suggested?
That will wipe away any advantage that using BOMs gives me.
Is there a better solution which I'm not yet aware of?
Kind regards
Karl Heinz Marbaise
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