exists-maven-plugin
Check if a maven artifact exists. Designed around the use case of skipping deployment if the stable version already exists.
How This Plugin Determines if Builds are the "Same"
There are two strategies to determine if a maven artifacts are the "same" as what the project just built: version comparison, and checksum comparison. By default, this plugin uses version comparison. Version comparison simply checks if the group:artifact:version matches an artifact in the local or remote repository. This simple check will not catch the situation where the developer has failed to update the version in pom.xml.
Alternatively, when <cmpChecksum> is true, this plugin compares the checksum of the local or remote
artifact with the just built artifact. Checksum comparison requires that the maven build be
reproducible. Without specific configuration, maven builds are not reproducible. See
Configuring for Reproducible Builds
for details on making your build reproducible.
Goals
There are two goals: local checks if the just built artifact is already in the local repository; and remote checks if the just built artifact is already in the remote repository.
Mojo details at plugin info
Parameters
Every parameter can be set with a maven property exists.<parameter_name>. e.g. skip parameter can be set from command line -Dexists.skip=true.
In the following table p: indicates the default constituent properties are prefixed with
project. and dm: indicates the default constituent properties are prefixed with
project.distributionManagement. e.g. for artifact parameter, the full default is
${project.artifactId}-${project.version}.${project.packaging}
| Parameter | Default | Description |
|---|---|---|
| artifact | p: |
The artifact within the project to query |
| cmpChecksum | false | Compare checksums of artifacts |
| failIfExists | false | Fail the build if the artifact already exists |
| failIfNotExists | false | Fail the build if the artifact does not exist |
| failIfNotMatch | false | Fail the build if the artifact exists and cmpChecksum is set and checksums do not match |
| lastSnapshotTime | The property to set with the timestamp of the last snapshot install / deploy | |
| project | p: |
The project within the repository to query |
| property | ${maven.deploy.skip} or ${maven.install.skip} | The property to receive the result of the query |
| repository | dm: ${repository.url} | For remote goal, the repository to query for artifacts |
| requireGoal | Execute goal only if requireGoal value matches one of the maven command line goals | |
| serverId | dm: ${repository.id} | For remote goal, the server ID to use for authentication and proxy settings |
| skip | false | Skip executing the plugin |
| skipIfSnapshot | true | Skip the query if the project ends with -SNAPSHOT |
| snapshotRepository | dm: ${snapshotRepository.url} | For remote goal, the repository to query for snapshot artifacts |
| snapshotServerId | dm: ${snapshotRepository.id} | For remote goal, the server ID to use for snapshot authentication and proxy settings |
| userProperty | false | If the property should be set as a user property, to be available in child projects |
Requirements
- Maven 3.5 or later
- Java 11 or later
Typical Use
<build>
<plugins>
<plugin>
<groupId>org.honton.chas</groupId>
<artifactId>exists-maven-plugin</artifactId>
<version>0.8.0</version>
<executions>
<execution>
<goals>
<goal>remote</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>Snapshot builds
When checking snapshot builds against a remote/local repository, the last deployed/installed
snapshot of the correct version will be matched. Optionally, you can configure a property with
the lastSnapshotTime parameter which will receive the build timestamp. If you need additional date
math on the timestamp value, open a feature request with your use case.
Preventing failures of remote goal
Consider the scenario where there is an artifact that can only be deployed from a specific build server to a corporate repository with a specialized workflow that ensures various security and license policies. The exists-maven-plugin remote goal is also used to avoid duplicate deployments.
Running maven with the install phase will cause the exists-maven-plugin to execute the remote
task. This might fail for various reasons; including the developer laptop is not connected to the
internet, or the corporate repository is only available to specific build machines.
We could change the binding of the remote goal to the deploy phase. However, the
maven-deploy-plugin's deploy goal will run before exists-maven-plugin's remote goal because
"When multiple executions are given that match a particular phase, they are executed in the order
specified in the POM, with inherited executions running first."
The solution is to leave the remote goal bound to the install phase and add a requireGoal
configuration:
<configuration>
<!-- run only if deploy goal is specified in maven command line -->
<requireGoal>deploy</requireGoal>
</configuration>