眼瞎了。。。

原来pom文件是这样的：

居然放在了 pluginManagement中！！！

<build>
        <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
                <plugin>
                    <groupId>com.spotify</groupId>
                    <artifactId>docker-maven-plugin</artifactId>
                    <configuration>
                        <imageName>${imageName}</imageName>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>

改成 plugins 节点：

<build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>

            <plugin>
                <groupId>com.spotify</groupId>
                <artifactId>docker-maven-plugin</artifactId>
                <configuration>
                    <imageName>${imageName}</imageName>
                </configuration>
            </plugin>
        </plugins>
    </build>