Where is the default Maven tomcat plugin configured?

Question

In a Maven project I can use the tomcat plugin without adding it to the POM. So I can deploy and run my webapp for example like this:

mvn clean install tomcat:run

I know that it is using some default configuration, but my question is why Maven allows me to use this plugin even though I haven't configured it? It also isn't in the super POM. So I have no idea where it's configuration comes from. Does anyone know?

Answer 1

Maven has some conventions about it, even if you do not configure anything in the project POM or in your settings.xml . When you invoke a plugin that way in the command line, Maven tries to find the plugin by adding one of the following groupId's:

• org.apache.maven.plugins
• org.codehaus.mojo

For the artifactId, it also tries to complete the "prefix" you specify (here tomcat ) with one of these:

• maven-${prefix}-plugin : (convetion for official plugins) -> maven-tomcat-plugin
• ${prefix}-maven-plugin : (convention for 3rd party plugins) -> tomcat-maven-plugin

And for the version, it just tries to get the latest available.

In your particular case, there is a match for the defaults: org.codehaus.mojo:tomcat-maven-plugin:1.1 (or any other available version).

A bit more detail here about the mechanics, and how you can also use these conventions for your own groupId's.