In maven, can I define a variable used in another pom? - maven

I'm getting an error when running maven build (unable to load a dependency).
[ERROR] Failed to execute goal on . . .
Could not transfer artifact my.group:libme1:${someVariable} from/to . . .
I believe that the developer that published this artifact was supposed to be setting the variable ${someVariable} but didn't. I think this is a bug but I'm trying to work around it by setting the variable.
The POM for the JAR I'm depending on my.group:libme1:1.2.3 looks like this (snippet highlighting the issue):
<groupId>my.group</groupId>
<artifactId>libme1</artifactId>
<parent>
<groupId>my.group</groupId>
<artifactId>libme1-parent</artifactId>
<version>${someVariable}</version>
</parent>
I tried defining it by adding -DsomeVariable=1.2.3 on the command line but it didn't work. For example, this command
mvn -DsomeVariable=1.2.3 clean install
should work based on Baeldung's article but doesn't.
I also ran:
mvn -DsomeVariable=1.2.3 help:effective-pom
and I see the variable being set, so I know he POM I'm using has that defined, but for some reason another POM doesn't pick up that value (or that is how it appears to me).
Is there any way to set the variable so it can be used in another POM? I'm guessing this is not possible.
Searching for an answer I found:
The maven doc
https://maven.apache.org/settings.html#Activation
If you know that this is bug, please let me know. I'm also reaching out to the publish of the artifact to ask them how this is supposed to work.

Basically the dependency's pom is invalid, the reasoning is following:
maven allows developers to do following things:
define dependencies in parent pom
impose restrictions on dependencies via <dependencyManagement> in both current and parent pom
use placeholders ${...} in <version> element, which somehow get resolved via system properties and current/parent pom properties
all those features mentioned above are very convenient from development perspective, however when you publish artifacts those features cause a pain in behind: that became not possible to use external library without it's parent pom, because parent pom may define dependencies and properties.
In your particular case someone have define version of parent pom as ${someVariable}, that in turn means it is not possible to use that library without information about the value of ${someVariable}. However, even if you had known the "correct" value of ${someVariable} and might specify it via system properties, that would cause some weird behaviour: today you may specify one value for ${someVariable}, tomorrow you (or someone else) will specify another value and ultimately you will get different builds, due to that maven denies such configurations (that is much better to fail a build rather than build something unreliable), that would be wiser to initially deny publishing such poms, but we have what we have.

It might be that the variable was stored in some user's settings.xml.
This would allow checking out an older version already in production for writing patches.
<settings>
...
<profiles>
<profile>
<id>work-in-progress</id>
<properties>
<someVariable>1.2.3</someVariable>
</properties>
</profile>
</profiles>
<activeProfiles>
<activeProfile>work-in-progress</activeProfile>
</activeProfiles>
</settings>
So you might do that too. And search in users' directories, .m2 repo directories where usually the settings.xml is stored.

Related

Setting application-specific properties on deploy by maven

I would like to deploy java app twice to one tomcat server, each time with different environment properties.
I would like to find a way like
mvn tomcat7:deploy -Denvironment=local
I don't mind using other maven plugin.
With no need to change files after deploy.
Is it somehow possible?
Thank you for you answer.
You can have a configuration file (something like e.g. application.properties) that you enable resource filtering for. You could then parameterize the values in that configuration file, and pass in different parameter values for each of the deployments (-Dkey1=value1 -Dkey2=value2).
You could pass the different parameter values on the command-line, or you could cement them in different profiles, and just activate the appropriate profile from the command-line (-Psecond-deployment).
What seems a little unfortunate from the suggested approach in your question is: in its most basic sense Maven is a build tool, meant to produce a consistent artifact from a build. This is no longer the case with the suggested approach in your question. If this is a web application that is never used as a dependency of other module, this may be fine. But just highlighting that different deployment configurations is a deployment concern, not a build concern.
I used little workaround.
I created different profiles which I use to update application property.
example:
In my POM I have:
<profiles>
<profile>
<id>local</id>
<properties>
<environment>local</environment>
....
</properties>
</profile>
and in application.property file I have
environment=#environment#
(That # are correct! )
This way I can deploy my app with defined environment by using command
mvn -P local tomcat7:deploy
and use environment variable anywhere else as ${environment}

Maven: Define SuperPOM property project.build.directory over command line

I am building my maven project with GitLab CI on a docker file.
I would like to configure my pipeline with a "compile" stage and a "test" stage. To be able to do that, I need to set the property project.build.directory, which is defined in the maven super POM, to the docker cache so the compiled artefact does not get lost between the jobs.
project.build.directory is a predefined maven property. Therefore I would think that I am able define it with the CL parameter -Dproject.build.directory=anotherDir. This somehow does not work and my project still gets built to the default directory target.
If I modify my POM with
<properties>
<buildDir>target</buildDir>
</properties>
<build>
<directory>${buildDir}</directory>
</build>
and call mvn clean install -DbuildDir=customTargetDir, my project gets built to the customTargetDir as expected.
Why is that? I really don't see a difference. I both cases, I define the value of an existing property.

Maven install goal does not generate pom for modules

I'm running a multi-module maven project and have an unexpected behavior. First time I'm seeing this...
My parent module configures the install plugin, defining its classifier.
<plugin>
<artifactId>maven-install-plugin</artifactId>
<configuration>
<generatePom>true</generatePom>
<classifier>${env}</classifier>
</configuration>
</plugin>
<!-- ... -->
<modules>
<module>webapp-formation</module>
<module>db-formation</module>
</modules>
But when I'm running mvn install the .pom files are not generate for my modules. Only my parent is associated with a .pom file in my repositories. Thus trying to browse to my module's artifact on Archiva (after running mvn depoy of course!) it simply fails. I can browse to the parent but not its children.
So... I need to add the undocumented attribute generatePom to my plugin configuration to have the .pom files generated --copied would be a better word actually-- for all my modules. --I said undocumented attribute because this attribute is documented only for the install-file goal which is not the one ran by default. The install goal is not expecting that attribute...
Of course, if I do not configure my install plugin --so not configuring the classifier-- I have no problem and all .pom files are generated properly.
For you guys, is that a normal behavior? Something that you have already seen? Or should I just file a bug?
Thanks,
Olivier.
What you describe as an undocumented attribute is simply wrong, cause the attributes are specific on a goal base which means the given configuration will not change anything, cause the generatePom attribute is only valid for install-file goal. So you can remove it.
In general such configuration does not make sense, cause if you have different environments you should go a different way. Just removed hte configuration with <classifier>${env}</classifier> as well and try to deploy via:
mvn clean deploy

Get version from directory name

I have bunch of projects. All of them must have the same version = branch directory name("7.15.0" for example).
To achieve that, i make one parent pom with code:
<version>${branch}</version>
<properties>
<branch>${project.file.parentFile.parentFile.parentFile.name}</branch>
</properties>
Most of my projects and subprojects are in directories, where ../.. is branch directory. Their poms contains this:
<parent>
<groupId>parentPomGroupId</groupId>
<artifactId>parentPomArtifactId</artifactId>
<version>${branch}</version>
</parent>
But not all projects is on the same level, so i must control and check where they is, and if needed add to their pom correct branch path:
<properties>
<branch>${project.file.parentFile.parentFile.name}</branch>
</properties>
also when project builds, in the log i see :
[INFO] Building appcore-utils ${project.file.parentFile.parentFile.name}
If i set constant in branch - log contains version. Tell me please, how can i resolve property "branch" only once in my parent pom? So if i use ${branch} in child project, it resolves to constant, which already calculated in parent pom. Or maybe there is another way to use branch directory name in version of projects?
I don't think that the goal you're trying to achieve is valid in terms of the current (3.1+) maven. The version tag now should be filled with a constant despite the fact that a while ago it could be possible to use an expression there as described in Maven version with a property , look at the last comment by #JanPeta. BTW the solution by Frederic Close doesn't work anymore (for maven-3.1.1 installed in my system).
Alternatively you can change the version of the artifacts generated in your project, and I have a working solution for that (instead of taking version from a directory name, I use git describe... output) but it's really, really ugly and now I think it's not worth the time I spent fixing all the issues with this approach.

Maven: Selecting Parent Project Based On Profile

I have a maven project - it is a plugin for jenkins. It's parent should be a:
<parent>
<groupId>org.jenkins-ci.plugins</groupId>
<artifactId>plugin</artifactId>
<version>1.414</version>
</parent>
But at the same time this plugin can be also used for hudson, without changing any line of code. But the parent project for it should be:
<parent>
<groupId>org.jvnet.hudson.plugins</groupId>
<artifactId>hudson-plugin-parent</artifactId>
<version>2.0.1</version>
</parent>
Can I specify 2 different profiles for that and use them to build plugin for jenkins or hudson accordingly? So that I call something like that:
mvn package -P jenkins
or
mvn package -P hudson
I have tried to specify properties in profiles, but those are not replaced by their values inside the <parent> tag. So is there any other possibility to build plugin for both, but with as much as possible common code and files?
Added: So, if I cannot do that, what should I do then? How to refactor? What the new structure should be?
As already mentioned, this is not possible.
Also, it is not possible to set a property for the parent's version as the interpolation for that happens a lot earlier than the handling of the profiles.
I would suggest that you create a masterbuild project as follows:
master
|-plugin-jenkins
|-plugin-hudson
|-plugin-assembly
The master should build all three as usual. However, in the assembly, you could add each of the two plugins as dependencies in separate profiles. And... each of these plugins can have the parent you like.
This is obviously somewhat a deviation from the Maven convention, but I believe it is a solution to your problem.
It's not possible because the tag "parent" is not available in the profiles section of the pom.
Currently we decided to stick with 1 repository and 2 separate pom.xml files, giving maven key which pom.xml use to build the project.
mvn package -f pom-jenkins.xml
mvn package -f pom-hudson.xml
No you cannot do that. you will have to refactor somehow to avoid the necessity.
As mentioned already not possible. I would suggest to make separate projects for jenkins plugin and hudson plugin. I assume that in not that far future that will not work anymore cause Hudons and Jenkins will diverge.
In general, you should be able to set the {group,artifact}Id and version of the parent POM via Java System Properties or Environment Variables, but it seems there is a Bug in Maven which will only be fixed in 4.x:
https://issues.apache.org/jira/browse/MNG-624
Another solution is to delegate the inclusion of the parent POM to your own parent POMs which you reference in the relativePath element, and change the content of the target e.g. via a symlink or cp command.
So in the main POM you would write:
<parent>
<groupId>org.mycompany.project</groupId>
<artifactId>foo-artifact</artifactId>
<version>1.0.0</version>
<relativePath>./my-parent.pom</relativePath>
</parent>
And in my-parent-jenkins you would just put:
<groupId>org.mycompany.project</groupId>
<artifactId>foo-artifact</artifactId>
<version>1.0.0</version>
<parent>
<groupId>org.jenkins-ci.plugins</groupId>
<artifactId>plugin</artifactId>
<version>1.414</version>
</parent>
The same project information with the block for hudson you put in my-parent-hudson.pom.
No you can either use
ln -s my-parent-jenkins.pom my-parent.pom
or
ln -s my-parent-hudson.pom my-parent.pom
to include the respective parent POM without the need to maintain two different main POM files for your project.
In case POM does not exist at the place referenced in relativePath, Maven will look up the POM in the remote repository[1], which is also an easy way to overwrite a parent POM locally.
[1] http://maven.apache.org/components/ref/3.3.9/maven-model/maven.html#class_parent

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