使用Docker部署Sling Bundle后遇404报错，请求排查问题

问题描述 #

尝试通过Docker镜像搭建Sling应用，操作步骤如下：

• 启动Docker镜像：docker run --rm -p 8080:8080 apache/sling:snapshot
• 创建Maven项目SlingSample，pom.xml配置如下：

<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.example</groupId>
  <artifactId>SlingSample</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>bundle</packaging>
  <name>Sling Sample Bundle</name>
  <description>A sample Sling servlet bundle.</description>

  <dependencies>
    <dependency>
      <groupId>org.apache.sling</groupId>
      <artifactId>org.apache.sling.api</artifactId>
      <version>2.23.0</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.0.1</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>org.apache.sling</groupId>
      <artifactId>org.apache.sling.servlets.annotations</artifactId>
      <version>1.0.0</version>
    </dependency>
    <dependency>
      <groupId>org.osgi</groupId>
      <artifactId>org.osgi.service.component.annotations</artifactId>
      <version>1.4.0</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.1</version>
        <configuration>
          <source>11</source>
          <target>11</target>
        </configuration>
      </plugin>
      <plugin>
        <groupId>org.apache.felix</groupId>
        <artifactId>maven-bundle-plugin</artifactId>
        <version>5.1.8</version>
        <extensions>true</extensions>
        <configuration>
          <instructions>
            <Bundle-SymbolicName>${project.artifactId}</Bundle-SymbolicName>
            <Bundle-Activator>org.example.Activator</Bundle-Activator>
            <Export-Package>org.example.*</Export-Package>
            <Sling-Servlet-Paths>/bin/helloworld</Sling-Servlet-Paths>
          </instructions>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

• 编写HelloWorldServlet代码：

package com.example;

import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.SlingHttpServletResponse;
import org.apache.sling.api.servlets.HttpConstants;
import org.apache.sling.api.servlets.SlingAllMethodsServlet;
import org.apache.sling.servlets.annotations.SlingServletPaths;
import org.apache.sling.servlets.annotations.SlingServletResourceTypes;
import org.osgi.service.component.annotations.Component;
import javax.servlet.Servlet;
import java.io.IOException;

@Component(service = {Servlet.class})
@SlingServletPaths("/bin/helloworld")
@SlingServletResourceTypes(
        resourceTypes = "sling/servlet/default",
        selectors = "HelloWorldServlet",
        extensions = "txt")
public class HelloWorldServlet extends SlingAllMethodsServlet {

    @Override
    protected void doGet(SlingHttpServletRequest request, SlingHttpServletResponse response) throws IOException {
        response.setContentType("text/plain");
        response.getWriter().write("Hello, World!");
    }
}

• 执行mvn clean install生成jar包；
• 在容器中创建/opt/sling/install目录，执行docker cp target/SlingSample-1.0-SNAPSHOT.jar <container_id>:/opt/sling/install/复制jar包。

遇到的问题：

• 访问http://localhost:8080/bin/helloworld返回404错误：

Resource at '/bin/helloworld' not found: No resource found (404)
The requested URL /bin/helloworld resulted in an error in org.apache.sling.servlets.resolver.internal.defaults.DefaultErrorHandlerServlet.

• 在http://localhost:8080/system/console/bundles中找不到SlingSample bundle。

排查与修复步骤 #

1. 移除不存在的Bundle Activator配置 #

pom.xml中配置了<Bundle-Activator>org.example.Activator</Bundle-Activator>，但未编写对应的org.example.Activator类，这会导致bundle无法被OSGi容器正常识别和启动。修改maven-bundle-plugin的instructions，删除这一行配置：

<!-- 移除该行 -->
<Bundle-Activator>org.example.Activator</Bundle-Activator>

2. 使用Docker容器内的正确安装目录 #

apache/sling:snapshot镜像的默认监听安装目录是/app/sling/install，而非你创建的/opt/sling/install。先进入容器验证路径：

docker exec -it <container_id> bash
ls /app/sling/install

重新复制jar包到正确路径：

docker cp target/SlingSample-1.0-SNAPSHOT.jar <container_id>:/app/sling/install/

3. 对齐依赖版本与Sling镜像版本 #

你使用的依赖版本（如org.apache.sling.api:2.23.0）较旧，与snapshot版本的Sling存在兼容性风险。建议通过Sling BOM统一管理依赖版本，在pom.xml中添加：

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>org.apache.sling</groupId>
      <artifactId>org.apache.sling.bom</artifactId>
      <version>12</version>
      <scope>import</scope>
      <type>pom</type>
    </dependency>
  </dependencies>
</dependencyManagement>

然后移除各依赖的version标签，让BOM自动匹配兼容版本。

4. 简化Servlet注解配置 #

同时使用@SlingServletPaths和@SlingServletResourceTypes可能造成解析冲突，建议先保留单一配置测试。比如只保留路径注解：

@Component(service = {Servlet.class})
@SlingServletPaths("/bin/helloworld")
public class HelloWorldServlet extends SlingAllMethodsServlet {
    // 原有doGet方法代码不变
}

5. 验证Bundle状态 #

复制jar包后，刷新http://localhost:8080/system/console/bundles，如果仍未找到目标bundle，查看容器日志排查具体错误：

docker logs <container_id>

日志会明确显示bundle加载失败的原因（如依赖缺失、类找不到等）。

内容的提问来源于stack exchange，提问作者ANAKHA ANIE JOSE 190768