A case tutorial for troubleshooting HTTP requests returning 401 (#1341)

tutorials/katacoda/case-http-401-cn/arthas-boot.md

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+
+
+
+
+在新的`Terminal 2`里，下载`arthas-boot.jar`，再用`java -jar`命令启动：
+
+`wget https://alibaba.github.io/arthas/arthas-boot.jar
+java -jar arthas-boot.jar`{{execute T2}}
+
+`arthas-boot`是`Arthas`的启动程序，它启动后，会列出所有的Java进程，用户可以选择需要诊断的目标进程。
+
+选择第一个进程，输入 `1`{{execute T2}} ，再`Enter/回车`：
+
+Attach成功之后，会打印Arthas LOGO。输入 `help`{{execute T2}} 可以获取到更多的帮助信息。
+
+![Arthas Boot](/arthas/scenarios/common-resources/assets/arthas-boot.png)

tutorials/katacoda/case-http-401-cn/case-http-401.md

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+
+
+在这个案例里，展示排查HTTP 401问题的技巧。
+
+访问： https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/admin
+
+结果是：
+
+```
+Something went wrong: 401 Unauthorized
+```
+
+我们知道`401`通常是被权限管理的`Filter`拦截了，那么到底是哪个`Filter`处理了这个请求，返回了401？
+
+
+### 跟踪所有的Filter函数
+
+开始trace：
+
+`trace javax.servlet.Filter *`{{execute T2}}
+
+访问： https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/admin
+
+可以在调用树的最深层，找到`AdminFilterConfig$AdminFilter`返回了`401`：
+
+```
++---[3.806273ms] javax.servlet.FilterChain:doFilter()
+|   `---[3.447472ms] com.example.demo.arthas.AdminFilterConfig$AdminFilter:doFilter()
+|       `---[0.17259ms] javax.servlet.http.HttpServletResponse:sendError()
+```
+
+### 通过stack获取调用栈
+
+上面是通过`trace`命令来获取信息，从结果里，我们可以知道通过`stack`跟踪`HttpServletResponse:sendError()`，同样可以知道是哪个`Filter`返回了`401`
+
+执行：
+
+`stack javax.servlet.http.HttpServletResponse sendError 'params[0]==401'`{{execute T2}}
+
+访问： https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/admin
+
+```bash
+$ stack javax.servlet.http.HttpServletResponse sendError 'params[0]==401'
+Press Q or Ctrl+C to abort.
+Affect(class-cnt:2 , method-cnt:4) cost in 87 ms.
+ts=2019-02-15 16:44:06;thread_name=http-nio-8080-exec-6;id=16;is_daemon=true;priority=5;TCCL=org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedWebappClassLoader@8546cd5
+    @org.apache.catalina.connector.ResponseFacade.sendError()
+        at com.example.demo.arthas.AdminFilterConfig$AdminFilter.doFilter(AdminFilterConfig.java:38)
+        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
+        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
+        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
+        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
+```

tutorials/katacoda/case-http-401-cn/finish.md

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+
+通过本教程基本掌握了Arthas排查HTTP请求返回401。更多高级特性，可以在下面的进阶指南里继续了解。
+
+* [Arthas进阶](https://alibaba.github.io/arthas/arthas-tutorials?language=cn&id=arthas-advanced)
+* [Arthas Github](https://github.com/alibaba/arthas)
+* [Arthas 文档](https://alibaba.github.io/arthas/)
+
+欢迎关注公众号，获取Arthas项目的信息，源码分析，案例实践。
+
+![Arthas公众号](/arthas/scenarios/common-resources/assets/qrcode_gongzhonghao.jpg)

tutorials/katacoda/case-http-401-cn/index.json

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+{
+  "title": "Arthas 排查HTTP请求返回401 案例",
+  "description": "Arthas 排查HTTP请求返回401 案例",
+  "difficulty": "高级使用者",
+  "time": "10分钟",
+  "details": {
+    "steps": [
+      {
+        "title": "Start demo",
+        "text": "start-demo.md"
+      },
+      {
+        "title": "Start arthas-boot",
+        "text": "arthas-boot.md"
+      },
+      {
+        "title": "排查HTTP请求返回401",
+        "text": "case-http-401.md"
+      }
+    ],
+    "intro": {
+      "text": "intro.md"
+    },
+    "finish": {
+      "text": "finish.md"
+    },
+    "assets": {
+      "host01": []
+    }
+  },
+  "environment": {
+    "uilayout": "terminal",
+    "showdashboard": true,
+    "dashboards": [
+      {
+        "name": "Web Port 80",
+        "port": 80
+      }
+    ]
+  },
+  "backend": {
+    "imageid": "java",
+    "environmentsprotocol": "http"
+  }
+}

tutorials/katacoda/case-http-401-cn/intro.md

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+
+
+
+![Arthas](https://alibaba.github.io/arthas/_images/arthas.png)
+
+`Arthas` 是Alibaba开源的Java诊断工具，深受开发者喜爱。在线排查问题，无需重启；动态跟踪Java代码；实时监控JVM状态。
+
+`Arthas` 支持JDK 6+，支持Linux/Mac/Windows，采用命令行交互模式，同时提供丰富的 `Tab` 自动补全功能，进一步方便进行问题的定位和诊断。
+
+* Github: https://github.com/alibaba/arthas
+* 文档: https://alibaba.github.io/arthas/

tutorials/katacoda/case-http-401-cn/start-demo.md

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+
+
+
+
+下载`demo-arthas-spring-boot.jar`，再用`java -jar`命令启动：
+
+`wget https://github.com/hengyunabc/spring-boot-inside/raw/master/demo-arthas-spring-boot/demo-arthas-spring-boot.jar
+java -jar demo-arthas-spring-boot.jar`{{execute T1}}
+
+`demo-arthas-spring-boot`是一个很简单的spring boot应用，源代码：[查看](https://github.com/hengyunabc/spring-boot-inside/tree/master/demo-arthas-spring-boot)
+
+启动之后，可以访问80端口： https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com
+
+![Demo Web](/arthas/scenarios/common-resources/assets/demo-web.png)

tutorials/katacoda/case-http-401-en/arthas-boot.md

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+
+
+
+
+In the new `Terminal 2`, download `arthas-boot.jar` and start with the `java -jar` command:
+
+`wget https://alibaba.github.io/arthas/arthas-boot.jar
+java -jar arthas-boot.jar`{{execute T2}}
+
+`arthas-boot` is the launcher for `Arthas`. It lists all the Java processes, and the user can select the target process to be diagnosed.
+
+Select the first process, type `1`{{execute T2}} ，then type `Enter`：
+
+After the Attach is successful, Arthas LOGO is printed. Enter `help`{{execute T2}} for more help.
+
+![Arthas Boot](/arthas/scenarios/common-resources/assets/arthas-boot.png)

tutorials/katacoda/case-http-401-en/case-http-401.md

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+
+
+In this case, the user will resolve the HTTP 401 issue.
+
+Visit: https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/admin
+
+The result is:
+
+```
+Something went wrong: 401 Unauthorized
+```
+
+We know that `401` is usually intercepted by the permission-managed `Filter`, so which `Filter` returns 401?
+
+
+### Track all Filter methods
+
+Start trace:
+
+`trace javax.servlet.Filter *`{{execute T2}}
+
+Visit: https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/admin
+
+At the deepest level of the call tree, you can find `AdminFilterConfig$AdminFilter` which returns `401`:
+
+```
++---[3.806273ms] javax.servlet.FilterChain:doFilter()
+|   `---[3.447472ms] com.example.demo.arthas.AdminFilterConfig$AdminFilter:doFilter()
+|       `---[0.17259ms] javax.servlet.http.HttpServletResponse:sendError()
+```
+
+### Get the call stack through stack command
+
+From the above result, we can find the method: `HttpServletResponse:sendError()`. So we can use `stack` command to resolved the HTTP `401` issue.
+
+
+Run:
+
+`stack javax.servlet.http.HttpServletResponse sendError 'params[0]==401'`{{execute T2}}
+
+Visit: https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/admin
+
+The Result:
+
+```bash
+$ stack javax.servlet.http.HttpServletResponse sendError 'params[0]==401'
+Press Q or Ctrl+C to abort.
+Affect(class-cnt:2 , method-cnt:4) cost in 87 ms.
+ts=2019-02-15 16:44:06;thread_name=http-nio-8080-exec-6;id=16;is_daemon=true;priority=5;TCCL=org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedWebappClassLoader@8546cd5
+    @org.apache.catalina.connector.ResponseFacade.sendError()
+        at com.example.demo.arthas.AdminFilterConfig$AdminFilter.doFilter(AdminFilterConfig.java:38)
+        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
+        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
+        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
+        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
+```

tutorials/katacoda/case-http-401-en/case-watch-method-exception.md

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+
+
+Currently, visiting http://localhost/user/0 will return a 500 error:
+
+`curl http://localhost/user/0`{{execute T3}}
+
+```
+{"timestamp":1550223186170,"status":500,"error":"Internal Server Error","exception":"java.lang.IllegalArgumentException","message":"id < 1","path":"/user/0"}
+```
+
+But what are the specific parameters of the request, what is the exception stack?
+
+### View the parameters/exception of UserController
+
+Execute in Arthas:
+
+`watch com.example.demo.arthas.user.UserController * '{params, throwExp}'`{{execute T2}}
+
+
+1. The first argument is the class name, which supports wildcards.
+2. The second argument is the function name, which supports wildcards.
+
+Visit `curl http://localhost/user/0`{{execute T3}} , the `watch` command will print the parameters and exception
+
+```bash
+$ watch com.example.demo.arthas.user.UserController * '{params, throwExp}'
+Press Q or Ctrl+C to abort.
+Affect(class-cnt:1 , method-cnt:2) cost in 53 ms.
+ts=2019-02-15 01:35:25; [cost=0.996655ms] result=@ArrayList[
+    @Object[][isEmpty=false;size=1],
+    @IllegalArgumentException[java.lang.IllegalArgumentException: id < 1],
+]
+```
+
+
+The user can see that the actual thrown exception is `IllegalArgumentException`.
+
+The user can exit the watch command by typing `Q`{{execute T2}} or `Ctrl+C`.
+
+If the user want to expand the result, can use the `-x` option:
+
+`watch com.example.demo.arthas.user.UserController * '{params, throwExp}' -x 2`{{execute T2}}
+
+### The return value expression
+
+In the above example, the third argument is the `return value expression`, which is actually an `ognl` expression that supports some built-in objects:
+
+* loader
+* clazz
+* method
+* target
+* params
+* returnObj
+* throwExp
+* isBefore
+* isThrow
+* isReturn
+
+You can use these built-in objects in the expressions. For example, return an array:
+
+`watch com.example.demo.arthas.user.UserController * '{params[0], target, returnObj}'`{{execute T2}}
+
+
+More references: https://alibaba.github.io/arthas/en/advice-class.html
+
+
+### The conditional expression
+
+The `watch` command supports conditional expressions in the fourth argument, such as:
+
+`watch com.example.demo.arthas.user.UserController * returnObj 'params[0] > 100'`{{execute T2}}
+
+When visit https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/user/1 , the `watch` command print nothing.
+
+When visit https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com/user/101 , the `watch` command will print:
+
+```bash
+$ watch com.example.demo.arthas.user.UserController * returnObj 'params[0] > 100'
+Press Q or Ctrl+C to abort.
+Affect(class-cnt:1 , method-cnt:2) cost in 47 ms.
+ts=2019-02-13 19:42:12; [cost=0.821443ms] result=@User[
+    id=@Integer[101],
+    name=@String[name101],
+]
+```
+
+### Capture when an exception occurs
+
+The `watch` command supports the `-e` option, which means that only requests that throw an exception are caught:
+
+`watch com.example.demo.arthas.user.UserController * "{params[0],throwExp}" -e`{{execute T2}}
+
+
+### Filter by cost
+
+The watch command supports filtering by cost, such as:
+
+`watch com.example.demo.arthas.user.UserController * '{params, returnObj}' '#cost>200'`{{execute T2}}

tutorials/katacoda/case-http-401-en/finish.md

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+
+Through this tutorial, you can know how to Troubleshooting HTTP request returns 401. More advanced features can be found in the Advanced Guide below.
+
+* [Arthas Advanced](https://alibaba.github.io/arthas/arthas-tutorials?language=en&id=arthas-advanced)
+* [Arthas Github](https://github.com/alibaba/arthas)
+* [Arthas Documentation](https://alibaba.github.io/arthas/en)

tutorials/katacoda/case-http-401-en/index.json

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+{
+  "title": "Arthas Troubleshooting HTTP request returns 401",
+  "description": "Arthas Troubleshooting HTTP request returns 401",
+  "difficulty": "expert",
+  "time": "10 minutes",
+  "details": {
+    "steps": [
+      {
+        "title": "Start demo",
+        "text": "start-demo.md"
+      },
+      {
+        "title": "Start arthas-boot",
+        "text": "arthas-boot.md"
+      },
+      {
+        "title": "Troubleshooting HTTP request returns 401",
+        "text": "case-http-401.md"
+      }  
+    ],
+    "intro": {
+      "text": "intro.md"
+    },
+    "finish": {
+      "text": "finish.md"
+    },
+    "assets": {
+      "host01": []
+    }
+  },
+  "environment": {
+    "uilayout": "terminal",
+    "showdashboard": true,
+    "dashboards": [
+      {
+        "name": "Web Port 80",
+        "port": 80
+      }
+    ]
+  },
+  "backend": {
+    "imageid": "java",
+    "environmentsprotocol": "http"
+  }
+}

tutorials/katacoda/case-http-401-en/intro.md

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+
+
+
+![Arthas](https://alibaba.github.io/arthas/_images/arthas.png)
+
+`Arthas` is a Java diagnostic tool open-sourced by Alibaba middleware team. Arthas helps developers in trouble-shooting issues in production environment for Java based applications without modifying code or restarting servers.
+
+`Arthas` supports JDK 6+, supports Linux/Mac/Windows.
+
+* Github: https://github.com/alibaba/arthas
+* Documentation: https://alibaba.github.io/arthas/en

tutorials/katacoda/case-http-401-en/start-demo.md

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+
+
+
+
+Download `demo-arthas-spring-boot.jar`, and start with `java -jar` command:
+
+`wget https://github.com/hengyunabc/spring-boot-inside/raw/master/demo-arthas-spring-boot/demo-arthas-spring-boot.jar
+java -jar demo-arthas-spring-boot.jar`{{execute T1}}
+
+`demo-arthas-spring-boot` is a simple Spring Boot demo, the source code here: [View](https://github.com/hengyunabc/spring-boot-inside/tree/master/demo-arthas-spring-boot)
+
+After booting, access port 80: https://[[HOST_SUBDOMAIN]]-80-[[KATACODA_HOST]].environments.katacoda.com
+
+![Demo Web](/arthas/scenarios/common-resources/assets/demo-web.png)