# Maven<no value>
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== Description

The Maven crawler looks recursively for all `pom.xml` files from a specific root directory, and tries to update the dependencies declared in each one.

Two things are updated per POM:

* every entry under `<dependencies>`
* the `<parent>` POM, when one is declared

This crawler is enabled by default, so it can be used either automatically by running `updatecli diff` from a directory containing the files to update, or by providing a manifest.
The automatic discovery behavior can be tuned by providing a YAML manifest with a `maven` crawler in top-level directive `autodiscovery` as explained in the link:/docs/core/autodiscovery/#_parameters["Autodiscovery" page].

== Generated manifests

Each dependency produces a link:{{< ref "maven" >}}[`maven`] source resolving the latest version, two link:{{< ref "xml" >}}[`xml`] conditions asserting that the `groupId` and `artifactId` still match, and an `xml` target writing the new version into the POM.

== Repositories, mirrors, and credentials

The repository used to look up a dependency is taken from the `<repositories>` declared in the POM, falling back to Maven Central.

Updatecli also reads `settings.xml`, looked up in this order:

. `settings.xml` next to the POM
. `$HOME/.m2/settings.xml`

From it, Updatecli applies:

* **mirrors** - a repository whose `id` or URL matches a `<mirrorOf>` rule is replaced by the mirror, including the `central` shorthand,
* **server credentials** - the `<username>` and `<password>` of the `<server>` whose `id` matches the repository.

The `MAVEN_MIRROR_URL` environment variable is honoured, and `${env.VARIABLE}` expressions inside `settings.xml` are interpolated.

== Version filtering

Unlike most crawlers, the version filter defaults to kind `latest`, because Maven coordinates do not reliably follow semantic versioning. Set an explicit `versionfilter` to constrain updates.

More details on the link:/docs/core/versionfilter/["Version Filtering" page].

== Limitations

* A dependency whose `<version>` is a property reference, such as `${junit.version}`, is skipped. Updatecli does not resolve the property to find the literal it should rewrite.
* Only files named exactly `pom.xml` are scanned.

== Manifest
=== Parameters

{{< autodiscoveryparameters "maven" >}}

=== Example

[source,yaml]
----
# updatecli.d/default.yaml
{{<include "assets/code_example/docs/plugins/autodiscovery/maven/updatecli.d/default.yaml">}}
----