Prior to this commit, the generated POMs for Spring Framework modules
would contain unneeded/harmful information from the Spring Framework
build:
1. The BOM imports applied to each module by the dependency
management plugin, for example for Netty or Reactor Netty.
Spring should not export that opinion to its POMs.
2. The exclusion of "org.slf4:jcl-over-slf4j" from *all* dependencies,
which made the POMs much larger than necessary and suggested to
developers that they should exclude it as well when using all those
listed dependencies. In fact, only Apache Tiles currently brings that
transitively.
This commit removes that information from the POMs.
The dependencyManagement Gradle plugin is disabled for POM generation
and we manually resolve the dependency versions during the generation
phase.
The Gradle build is streamlined to exclude "org.slf4:jcl-over-slf4j"
only when necessary.
Issue: SPR-16893
Previously the maven dependencies were specified in an arbitrary order
which made comparing the poms against other versions difficult.
This commit sorts the dependencies by scope, group id, and then
artifact id.
Replace existing 'optional' and 'provided' Spring specific build
extensions with a new Gradle propdeps-plugin. Optional and Provided
dependencies are now defined use dependency configurations.
The new plugin does not currently support the notion of optional
runtime dependencies. All optional dependencies are implicitly
part of the 'compile' scope. This is an intentional design decision
that aims to keep both the plugin and the build simple. Since optional
dependencies are non-transitive this restriction should not cause
any real problems for existing users. The only existing dependency
affected is 'commons-io' in the 'spring-beans' project, however, this
was an optional compile scope dependency in the previous Spring 3.1
release.
Both provided and optional dependencies are no longer exported from
generated eclipse .classpath files. This fixes several tests that
would previously fail when running within eclipse. The servlet-api
specific elements of ide.gradle are also no longer required.
Issue: SPR-9656, SPR-10070
Previously the publish-maven.gradle only supported having a single
artifact be marked as optional or provided. This causes problems now
that we are building modules that support multiple versions of an
artifact. For example, we compile against two versions of Tiles
artifacts with identical names, both of which need to be marked
optional.
This updates publish-maven.gradle to find all the artifacts and mark
them as optional as apposed to the first entry.
- Fix deprecation warnings about dynamic properties; favor use of
"extra properties extensions" per [1]
- Certain such deprecations are still issued due to violations within
the docbook-reference plugin. These will be fixed in an upcoming
revision of the plugin, at which point spring-framework will upgrade
to depend on it and these warnings will be eliminated
[1] http://gradle.org/docs/current/dsl/org.gradle.api.plugins.ExtraPropertiesExtension.html
Issue: SPR-9327
Understanding Gradle pom generation
-------------------------------------------
All spring-* subprojects have had Gradle's 'maven' plugin applied to
them. This means that one can run `gradle install`, and POMs will be
generated according to the metadata in the build.gradle file.
The 'customizePom' routine added by this commit hooks into this
generation process in order to add elements to the pom required for
entry into Maven Central via oss.sonatype.org[1].
This pom generation happens on-the-fly during `gradle install` and
the generated poms exist only in your local .m2 cache. Therefore,
you will not see the poms on the source tree after this command.
Handling optional and provided dependencies
-------------------------------------------
Note particularly the handling of 'optional' and 'provided'
dependencies. Gradle does not have a first class notion for these
concepts, nor are they significant to the actual Gradle build process,
but they are important when publishing POMs for consumption via Maven
Central and other Maven-compatible repositories.
<optional>true</optional> indicates that a dependency need not be
downloaded when resolving artifacts. e.g. spring-context has an
compile-time dependency on cglib, but when a Spring user resolves
spring-context from Maven Central, cglib should *not* automatically
be downloaded at the same time. This is because the core functionality
within spring-context can operate just fine without cglib on the
classpath; it is only if the user chooses explicitly to use certain
functionality, e.g. @Configuration classes, which do require cglib,
that the user must declare an explicit dependency in their own build
script on cglib.
Marking these kinds of dependencies as 'optional' provides a kind of
built in 'documentation' about which version of cglib the user should
declare if in fact he wishes to.
Spring has a great many compile-time dependencies, but in fact very
few mandatory runtime dependencies. Therefore, *most* of Spring's
dependencies are optional.
<scope>provided</scope> is similar to 'optional', in that dependencies
so marked should not be automatically downloaded during dependency
resolution, but indicates rather that they are expected to have been
provided by the user application runtime environment. For example, the
Servlet API is in fact a required runtime dependency for spring-webmvc,
but it is expected that it will be available via the user's servlet
container classpath. Again, it serves here as a kind of 'documentation'
that spring-webmvc does in fact expect the servlet api to be available,
and furthermore which (minimum) version.
This commit adds two closures named 'optional' and 'provided' as well as
two arrays (optionalDeps, providedDeps) for tracking which dependencies
are optional or provided. An optional dependency is declared as follows:
compile("group:artifact:version", optional)
Here, the optional closure accepts the dependency argument implicitly,
and appends it to the 'optionalDeps' array. Then, during pom generation
(again, the customizePom routine), these arrays are interrogated, and
pom <dependency> elements are updated with <optional>true</optional> or
<scope>provided</scope> as appropriate. Thanks to the Spock framework
for inspiration on this approach[2].
[1] http://bit.ly/wauOqP (Sonatype's central sync requirements)
[2] https://github.com/spockframework/spock/blob/groovy-1.7/gradle/publishMaven.gradle#L63
Brian Clozel
stonio
Sam Brannen
Brian Clozel
Phillip Webb
Rob Winch
Phillip Webb
Chris Beams