How to Refer Environment Variable in Pom.Xml

How to refer environment variable in POM.xml?

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

Maven read environment variable in properties file

You should probably first filter the properties file with the maven resources plugin. Afterwards myBatis plugin should work as intended.

See following gist for a short example to the resources plugin.

development.properties

# place in src/main/resources
username=${env.username}
password=${env.password}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.stackoverflow</groupId>
    <artifactId>question-48693420</artifactId>
    <version>1.0-SNAPSHOT</version>

    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>
</project>

Command line:

username=user1 password=pass1 mvn resources:resources && cat target/classes/development.properties

Console log:

(...)
[INFO] --- maven-resources-plugin:2.3:resources (default-cli) @ question-48693420 ---
(...)
[INFO] Copying 1 resource
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
(...)

username=user1
password=pass1

Intellij not recognising environment variable in pom.xml

Environment Variables can be referred in pom.xml using 'env.' prefix.

Please refer to Maven properties

For example,

env.PATH

Contains the current PATH in which Maven is running. The PATH contains a list of directories used to locate executable scripts and programs.

pom.xml environment variable with default fallback

You could use profiles to achieve this:

<profiles> 
    <profile>
        <id>buildnumber-defined</id>
        <activation>
            <property>
                <name>env.BUILD_NUMBER</name>
            </property>
        </activation>
        <properties>
            <buildnumber>${env.BUILD_NUMBER}</buildnumber>
        </properties>
    </profile>
    <profile>
        <id>buildnumber-undefined</id>
        <activation>
            <property>
                <name>!env.BUILD_NUMBER</name>
            </property>
        </activation>
        <properties>
            <buildnumber>0</buildnumber>
        </properties>
    </profile>
</profiles>

A bit more verbose than bash...

How to conditionally select a specific directory based on environment pom.xml

<profile>
   <id>prod</id>
   <activation>
      <property>
         <name>env</name>
         <value>prod</value>
      </property>
   </activation>
</profile>

This actually works if you set your env variable either via Explicitly using command console input or Through maven settings.

So this profile will be activated depending upon the env variable specified. We can also use !Prod, to select all non-prod environments.

Pom file not reading environment variables

Try adding this profile to your pom.xml (in <profiles/>):

<profile>
  <id>tools.jar</id>
  <activation>
    <file><exists>${java.home}/../lib/tools.jar</exists></file>
  </activation>
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>jdk</groupId>
        <artifactId>tools</artifactId>
        <version>${java.specification.version}</version>
        <scope>system</scope>
        <systemPath>${java.home}/../lib/tools.jar</systemPath>
      </dependency>
    </dependencies>
  </dependencyManagement>
  <build>
    <pluginManagement>
      <plugins>
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-antrun-plugin</artifactId>
          <dependencies>
            <dependency>
              <groupId>jdk</groupId>
              <artifactId>tools</artifactId>
              <version>${java.specification.version}</version>
              <scope>system</scope>
              <systemPath>${java.home}/../lib/tools.jar</systemPath>
            </dependency>
          </dependencies>
        </plugin>
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-javadoc-plugin</artifactId>
          <configuration>
            <docletPath>${tools.jar}</docletPath>
          </configuration>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</profile>

I've included the corresponding change to the javadoc plug-in which may or
may not be useful to you. You can remove it if you don't need it.

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