Maven does not replace a variable in 'settings.xml' when it is invoked

Question

I have defined a local mirror for all repositories in the settings.xml file:

<mirror>
  <id>myMirror</id>
  <mirrorOf>*</mirrorOf>
  <url>file://${mypath}/maven/.m2/repository</url>
</mirror>

I want that my mirror to point to a local path, in this case the path is:

file://${mypath}/maven/.m2/repository

Where ${mypath} is a variable that I pass when I invoke Maven:

 mvn -Dmypath="/D:/test" package

The problem is that Maven does not replace the variable when it is invoked. I can see that this error is happening by inspection of the build log. For example, Maven reports that it is downloading a file from file://${mypath}/maven/.m2/repository when the correct would be file:///D:/test/maven/.m2/repository.

I have also noted that Maven replaces correctly my variable when it is inserted in the url child tag of the repository tag:

<repository>
        <id>central</id>
        <url>http://${mypath}/maven/.m2/repository</url>
</repository>

The build works correctly when I replace the variable in my settings.xml by the complete URL like in the example below:

<mirror>
        <id>myMirror</id>
        <mirrorOf>*</mirrorOf>
        <url>file:///D:test/maven/.m2/repository</url>
</mirror>

Answer 1

I had a slightly different experience here from Rich's answer, so I think it's worth mentioning in a different one.

Variable substitution does indeed work inside a profile, but it seems to fail if you need them replaced before parent pom resolution happens.

I had the following configuration here:

<profiles>
  <profile>
    <id>company-dev</id>
    <properties>
      <company.repo.deployment.endpoint>https://companyartifacts.jfrog.io/companyartifacts</company.repo.deployment.endpoint>
      <company.repo.download.endpoint>https://companyartifacts.jfrog.io/companyartifacts</company.repo.download.endpoint>
    </properties>
    <repositories>
      ...
      <repository>
        <id>company-repo-snap</id>
        <name>libs-snapshots</name>
        <url>${company.repo.download.endpoint}/libs-snapshots</url>
        <snapshots>
          <enabled>true</enabled>
        </snapshots>
        <releases>
          <enabled>false</enabled>
        </releases>
      </repository>
    </repositories>
    </pluginRepositories>
  </profile>
</profiles>

It's been like that for years now, every place where I use company.repo.download.endpoint var seems to work great until I needed it to resolve a parent pom like this:

<project ...>
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.company.jcompany</groupId>
        <artifactId>persistence</artifactId>
        <version>5-SNAPSHOT</version>
    </parent>
    <artifactId>persistence-api</artifactId>
    <version>5.0.0-SNAPSHOT</version>
    ...
</project>

Then, I started having this exception, even running something as simple as mvn -X help:effective-pom only:

(notice variables are not replaced in URL)

[ERROR]   The project com.company.jcompany:persistence-api:5.0.0-SNAPSHOT (/var/lib/jenkins/jobs/jcompany_persistence_api-trunk/workspace/pom.xml) has 1 error
[ERROR]     Non-resolvable parent POM: Could not transfer artifact com.company.jcompany:persistence:pom:5-SNAPSHOT from/to company-repo-snap (${company.repo.download.endpoint}/libs-snapshots): No connector available to access repository company-repo-snap (${company.repo.download.endpoint}/libs-snapshots) of type default using the available factories WagonRepositoryConnectorFactory and 'parent.relativePath' points at wrong local POM @ line 5, column 10 -> [Help 2]
org.apache.maven.model.resolution.UnresolvableModelException: Could not transfer artifact com.company.jcompany:persistence:pom:5-SNAPSHOT from/to company-repo-snap (${company.repo.download.endpoint}/libs-snapshots): No connector available to access repository company-repo-snap (${company.repo.download.endpoint}/libs-snapshots) of type default using the available factories WagonRepositoryConnectorFactory
    at org.apache.maven.project.ProjectModelResolver.resolveModel(ProjectModelResolver.java:159)
    at org.apache.maven.model.building.DefaultModelBuilder.readParentExternally(DefaultModelBuilder.java:813)
    at org.apache.maven.model.building.DefaultModelBuilder.readParent(DefaultModelBuilder.java:664)
    at org.apache.maven.model.building.DefaultModelBuilder.build(DefaultModelBuilder.java:310)
    at org.apache.maven.model.building.DefaultModelBuilder.build(DefaultModelBuilder.java:232)

The only reasonable explanation I find for this problem is that parent pom resolution happens so early in the process that variables are not replaced yet. When I don't have to fetch snapshots for parent poms, then all variables are replaced successfully, as expected. Not sure if I should report this as a bug.

Using Maven 3.6.3 at time of answer, if that matters.