Maven dependency resolution and scope overriding
Running mvn dependency:tree
on the sample project posted in the bug link specified above,
[INFO] Building MEAR-143 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-dependency-plugin:2.3:tree (default-cli) @ mear-143 ---
[INFO] ljnelson:mear-143:pom:1.0-SNAPSHOT
[INFO] \- junit:junit:jar:4.8.2:test
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building MEAR-143 Leaf 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-dependency-plugin:2.3:tree (default-cli) @ mear-143-leaf ---
[INFO] ljnelson:mear-143-leaf:jar:1.0-SNAPSHOT
[INFO] \- junit:junit:jar:4.8.2:test
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building MEAR-143 Middle 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-dependency-plugin:2.3:tree (default-cli) @ mear-143-middle ---
[INFO] ljnelson:mear-143-middle:jar:1.0-SNAPSHOT
[INFO] +- ljnelson:mear-143-leaf:jar:1.0-SNAPSHOT:runtime
[INFO] \- junit:junit:jar:4.8.2:test
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building MEAR-143 EAR 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-dependency-plugin:2.3:tree (default-cli) @ mear-143-ear ---
[INFO] ljnelson:mear-143-ear:ear:1.0-SNAPSHOT
[INFO] +- ljnelson:mear-143-middle:jar:1.0-SNAPSHOT:runtime
[INFO] | \- ljnelson:mear-143-leaf:jar:1.0-SNAPSHOT:test (scope managed from ru
ntime)
[INFO] \- junit:junit:jar:4.8.2:test
The dependency scope
of mear-143-leaf
in mear-143-middle
, where the dependency is explicitly defined is indeed runtime
, overriding the test
scope defined in the dependencyManagement
section of parent pom, mear-143
.
In mear-143-ear
, mear-143-leaf
gets included transitively. Here the test
scope defined in dependencyManagement
of mear-143
takes precedence over the inherited runtime
scope.
This, I guess is in line with what is specified in the second bullet point in the section you have referred above. Quoting it here and highlighting in bold and italics the relevant parts:
b is defined in B's parent's dependency management section and since dependency management takes precedence over dependency mediation for transitive dependencies, version 1.0 will be selected should it be referenced in a or c's pom. b will also have compile scope
Laird Nelson
Devoted husband and father. Writing software at the intersection of Java EE, Kubernetes and microservices. Hammond B3 player living on Bainbridge Island, WA. General all-around nice guy.
Updated on July 04, 2020Comments
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Laird Nelson almost 4 years
Disclaimer
(I originally asked the question in a very detailed manner over here. I've excerpted it here as the
maven-users
mailing list has gone quiet on this question.) (not just another newbie question)Reference
My reference material is http://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html#Dependency_Management; please let me know in this discussion if this is outdated or wrong.
Question
There is a section in that document that begins with "A second, and very important...". In what follows I'll refer to that section's projects
A
andB
, and will excerpt from them.In that section, you will see that project
A
has a<dependencyManagement>
section that--among other things--defines an artifact,c
, as having scopecompile
:<!-- In A's pom.xml; condensed for brevity --> <dependencyManagement> <dependency> <groupId>test</groupId> <artifactId>c</artifactId> <version>1.0</version> <scope>compile</scope> <!-- look: compile scope --> </dependency> </dependencyManagement>
Then you will see a
pom.xml
for projectB
that (a) inherits from projectA
(thus inheriting itsdependencyManagement
section) and (b) establishes a dependency on artifactc
, without having to specify itsversion
. You will also notice that the dependency on artifactc
overrides the scope ofc
to beruntime
, notcompile
:<!-- In B's pom.xml, whose parent is A's pom.xml (above); condensed for brevity --> <dependencies> <dependency> <groupId>test</groupId> <artifactId>c</artifactId> <scope>runtime</scope> <!-- look: runtime scope --> </dependency> </dependencies>
Again, you'll note that there is no
<version>
element, but there is a<scope>runtime</scope>
element.My interpretation of this is that when all is said and done,
B
will depend on version1.0
of artifactc
inruntime
scope, notcompile
scope.Is that correct? My
maven-ear-plugin
bug rests on the fact that this is the expected behavior. It is not what happens when themaven-ear-plugin
builds an.ear
file.Next, if that's correct, I would also expect that if artifact
c
had any transitiveruntime
dependencies they would be available inB
'sruntime
classpath (as defined by the somewhat baffling table in http://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html#Dependency_Scope).Is that correct?
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Laird Nelson over 12 yearsThank you; realizing that it takes precedence even for scope (not just version) was the key thing missing for me.
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thecoop about 9 yearsIs there any way to override the scope of a managed dependency in a child pom?
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6ton almost 9 years@thecoop see stackoverflow.com/questions/31711024/…