maven-build-lifecycle

What this skill does

# Maven Build Lifecycle

Master Maven's build lifecycle including phases, goals, profiles, and build customization for efficient Java project builds.

## Overview

Maven's build lifecycle is a well-defined sequence of phases that execute in order. Understanding the lifecycle is essential for effective build configuration and optimization.

## Default Lifecycle Phases

### Complete Phase Order

```
1.  validate      - Validate project structure
2.  initialize    - Initialize build state
3.  generate-sources
4.  process-sources
5.  generate-resources
6.  process-resources - Copy resources to output
7.  compile       - Compile source code
8.  process-classes
9.  generate-test-sources
10. process-test-sources
11. generate-test-resources
12. process-test-resources
13. test-compile  - Compile test sources
14. process-test-classes
15. test          - Run unit tests
16. prepare-package
17. package       - Create JAR/WAR
18. pre-integration-test
19. integration-test - Run integration tests
20. post-integration-test
21. verify        - Run verification checks
22. install       - Install to local repo
23. deploy        - Deploy to remote repo
```

### Common Phase Commands

```bash
# Compile only
mvn compile

# Compile and run tests
mvn test

# Create package
mvn package

# Install to local repository
mvn install

# Deploy to remote repository
mvn deploy

# Clean and build
mvn clean install

# Skip tests
mvn install -DskipTests

# Skip test compilation and execution
mvn install -Dmaven.test.skip=true
```

## Clean Lifecycle

```
1. pre-clean
2. clean         - Delete target directory
3. post-clean
```

```bash
# Clean build artifacts
mvn clean

# Clean specific directory
mvn clean -DbuildDirectory=out
```

## Site Lifecycle

```
1. pre-site
2. site          - Generate documentation
3. post-site
4. site-deploy   - Deploy documentation
```

```bash
# Generate site
mvn site

# Generate and deploy site
mvn site-deploy
```

## Goals vs Phases

### Executing Phases

```bash
# Execute phase (runs all previous phases)
mvn package
```

### Executing Goals

```bash
# Execute specific goal
mvn compiler:compile
mvn surefire:test
mvn jar:jar

# Multiple goals
mvn dependency:tree compiler:compile
```

### Phase-to-Goal Bindings

```xml
<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.12.1</version>
            <executions>
                <execution>
                    <id>compile-sources</id>
                    <phase>compile</phase>
                    <goals>
                        <goal>compile</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>
```

## Build Profiles

### Profile Definition

```xml
<profiles>
    <profile>
        <id>development</id>
        <activation>
            <activeByDefault>true</activeByDefault>
        </activation>
        <properties>
            <env>dev</env>
            <skip.integration.tests>true</skip.integration.tests>
        </properties>
    </profile>

    <profile>
        <id>production</id>
        <properties>
            <env>prod</env>
            <skip.integration.tests>false</skip.integration.tests>
        </properties>
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <configuration>
                        <debug>false</debug>
                        <optimize>true</optimize>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </profile>
</profiles>
```

### Profile Activation

```bash
# Activate by name
mvn install -Pproduction

# Multiple profiles
mvn install -Pproduction,ci

# Deactivate profile
mvn install -P!development
```

### Activation Triggers

```xml
<profile>
    <id>jdk17</id>
    <activation>
        <!-- Activate by JDK version -->
        <jdk>17</jdk>
    </activation>
</profile>

<profile>
    <id>windows</id>
    <activation>
        <!-- Activate by OS -->
        <os>
            <family>windows</family>
        </os>
    </activation>
</profile>

<profile>
    <id>ci</id>
    <activation>
        <!-- Activate by environment variable -->
        <property>
            <name>env.CI</name>
            <value>true</value>
        </property>
    </activation>
</profile>

<profile>
    <id>with-config</id>
    <activation>
        <!-- Activate by file existence -->
        <file>
            <exists>src/main/config/app.properties</exists>
        </file>
    </activation>
</profile>
```

## Resource Filtering

### Enable Filtering

```xml
<build>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <filtering>true</filtering>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
        </resource>
        <resource>
            <directory>src/main/resources</directory>
            <filtering>false</filtering>
            <excludes>
                <exclude>**/*.properties</exclude>
                <exclude>**/*.xml</exclude>
            </excludes>
        </resource>
    </resources>
</build>
```

### Property Substitution

```properties
# application.properties
app.name=${project.name}
app.version=${project.version}
app.environment=${env}
build.timestamp=${maven.build.timestamp}
```

## Build Customization

### Source and Target Configuration

```xml
<properties>
    <maven.compiler.source>17</maven.compiler.source>
    <maven.compiler.target>17</maven.compiler.target>
    <maven.compiler.release>17</maven.compiler.release>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
```

### Custom Source Directories

```xml
<build>
    <sourceDirectory>src/main/java</sourceDirectory>
    <testSourceDirectory>src/test/java</testSourceDirectory>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
        </resource>
    </resources>
    <testResources>
        <testResource>
            <directory>src/test/resources</directory>
        </testResource>
    </testResources>
</build>
```

### Final Name and Output

```xml
<build>
    <finalName>${project.artifactId}-${project.version}</finalName>
    <directory>target</directory>
    <outputDirectory>target/classes</outputDirectory>
    <testOutputDirectory>target/test-classes</testOutputDirectory>
</build>
```

## Multi-Module Builds

### Reactor Options

```bash
# Build all modules
mvn install

# Build specific module and dependencies
mvn install -pl module-name -am

# Build dependents of a module
mvn install -pl module-name -amd

# Resume from specific module
mvn install -rf :module-name

# Build in parallel
mvn install -T 4
mvn install -T 1C  # 1 thread per CPU core
```

### Module Order Control

```xml
<!-- parent/pom.xml -->
<modules>
    <module>common</module>
    <module>api</module>
    <module>service</module>
    <module>web</module>
</modules>
```

## Test Configuration

### Surefire Plugin (Unit Tests)

```xml
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>3.2.3</version>
    <configuration>
        <includes>
            <include>**/*Test.java</include>
            <include>**/*Tests.java</include>
        </includes>
        <excludes>
            <exclude>**/*IntegrationTest.java</exclude>
        </excludes>
        <parallel>methods</parallel>
        <threadCount>4</threadCount>
        <forkCount>1</forkCount>
        <reuseForks>true</reuseForks>
    </configuration>
</plugin>
```

### Failsafe Plugin (Integration Tests)

```xml
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-failsafe-plugin</artifactId>