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About java : How-to-refer-environment-variable-in-POMxml

Question Detail

I am using maven as build tool. I have set an environment variable called env. How can I get access to this environment variable’s value in the pom.xml file?

Question Answer

Check out the Maven Properties Guide…

As Seshagiri pointed out in the comments, ${env.VARIABLE_NAME} will do what you want.

I will add a word of warning and say that a pom.xml should completely describe your project so please use environment variables judiciously. If you make your builds dependent on your environment, they are harder to reproduce

It might be safer to directly pass environment variables to maven system properties. For example, say on Linux you want to access environment variable MY_VARIABLE. You can use a system property in your pom file.

<properties>
    ...
    <!-- Default value for my.variable can be defined here -->
    <my.variable>foo</my.variable>
    ...
</properties>
...
<!-- Use my.variable -->
... ${my.variable} ...

Set the property value on the maven command line:

mvn clean package -Dmy.variable=$MY_VARIABLE

Also, make sure that your environment variable is composed only by UPPER CASE LETTERS…. I don’t know why (the documentation doesn’t say nothing explicit about it, at least the link provided by @Andrew White), but if the variable is a lower case word (e.g. env.dummy), the variable always came empty or null…

i was struggling with this like an hour, until I decided to try an UPPER CASE VARIABLE, and problem solved.

OK Variables Examples:

  • DUMMY
  • DUMMY_ONE
  • JBOSS_SERVER_PATH

(NOTE: I was using maven v3.0.5)

I Hope that this can help someone….

Can’t we use

<properties>
    <my.variable>${env.MY_VARIABLE}</my.variable>
</properties>

I was struggling with the same thing, running a shell script that set variables, then wanting to use the variables in the shared-pom. The goal was to have environment variables replace strings in my project files using the com.google.code.maven-replacer-plugin.

Using ${env.foo} or ${env.FOO} didn’t work for me. Maven just wasn’t finding the variable. What worked was passing the variable in as a command-line parameter in Maven. Here’s the setup:

  1. Set the variable in the shell script. If you’re launching Maven in a sub-script, make sure the variable is getting set, e.g. using source ./maven_script.sh to call it from the parent script.

  2. In shared-pom, create a command-line param that grabs the environment variable:

<plugin>
  ...
  <executions>
    <executions>
    ...
      <execution>
      ...
        <configuration>
          <param>${foo}</param> <!-- Note this is *not* ${env.foo} -->
        </configuration>
  1. In com.google.code.maven-replacer-plugin, make the replacement value ${foo}.

  2. In my shell script that calls maven, add this to the command: -Dfoo=$foo

You can use <properties> tag to define a custom variable and ${variable} pattern to use it

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

    <!-- define -->
    <properties>
        <property.name>1.0</property.name>
    </properties>

    <!-- using -->
    <version>${property.name}</version>

</project>

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