Maven read .properties to use in pom.xml

Question

Im trying to get the properties-maven-plugin to read from my .properties file. Flyway (which im trying to use the properties for) just keeps throwing errors about the db url being malformed, but works if i set the values within the pom.xml itself, rather than using the properties read from file.

Im using eclipse with the m2e plugin.

plugin config to read from .properties

<plugin>
  <groupId>org.codehaus.mojo</groupId>
  <artifactId>properties-maven-plugin</artifactId>
  <version>1.0-alpha-2</version>
  <executions>
    <execution>
      <phase>initialize</phase>
      <goals>
        <goal>read-project-properties</goal>
      </goals>
      <configuration>
        <files>
          <file>src/main/resources/config.properties</file>
        </files>
      </configuration>
    </execution>
  </executions>
</plugin>

Flyway config where the properties are being used

<plugin>
  <groupId>com.googlecode.flyway</groupId>
  <artifactId>flyway-maven-plugin</artifactId>
  <version>2.2.1</version>
  <executions>
    <execution>
     <phase>compile</phase>
      <goals>
        <goal>flyway:migrate</goal>
      </goals>
    </execution>
  </executions>
  <configuration>
    <driver>${db.driver}</driver>
    <url>${db.url}</url>
    <user>${db.user}</user>
    <password>${db.password}</password>
  </configuration>
  <dependencies>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.26</version>
    </dependency>
  </dependencies>
</plugin>

config.properties located in /src/main/resources/

# Database details
db.driver=com.mysql.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/dbname
db.user=username
db.pass=password

Ive tried looking through several other stackoverflow threads but none of the solutions seem to work. I'm new to maven and the whole thing seems to be throwing me, anyone got a light to shed?

Answer 1

There are basically two ways you can execute the Flyway migrate goal:

1. As part of a lifecycle phase: You have configured the Flyway plugin to be executed during the compile phase. That means you can just enter mvn compile and Flyway will be executed along with all other goals that are part of that lifecycle phase and all previous phases. Everything works fine, except you have a slight misconfiguration: The goal must not be prefixed. In order to fix this you have to provide the goal without prefix:

   <goals>
       <goal>migrate</goal>
   </goals>
   

   Now the execution works. Flyway gets all parameters from the properties-maven-plugin because it is executed in a previous phase.

2. Direct invocation: If you execute Flyway with mvn flyway:migrate, the plugin is invoked independent of any lifecycle phases. Since no phase is executed, the properties-maven-plugin is also not executed because it relies on the initialize phase - which effectively doesn't set any parameters. That's why Flyway complains about missing parameters.

Solution: If you want the properties-maven-plugin to work together with Flyway you have to execute Flyway as part of a lifecycle. If you don't want to invoke it with every compile phase, you could create a separate profile and only run this profile whenever you need a Flyway migration with mvn compile -PflywayMigration:

<profiles>
    <profile>
        <id>flywayMigration</id>
        <build>
            <plugins>
                <plugin>
                    <groupId>com.googlecode.flyway</groupId>
                    <artifactId>flyway-maven-plugin</artifactId>
                    <version>2.2.1</version>
                    <executions>
                        <execution>
                            <phase>compile</phase>
                            <goals>
                                <goal>migrate</goal>
                            </goals>
                        </execution>
                    </executions>
                    <configuration>
                        <driver>${db.driver}</driver>
                        <url>${db.url}</url>
                        <user>${db.user}</user>
                        <password>${db.password}</password>
                    </configuration>
                    <dependencies>
                        <dependency>
                            <groupId>mysql</groupId>
                            <artifactId>mysql-connector-java</artifactId>
                            <version>5.1.26</version>
                        </dependency>
                    </dependencies>
                </plugin>
            </plugins>
        </build>
    </profile>
</profiles>