SkyWalking

安装

使用 SkyWalking Java Agent

Apache SkyWalking的Java代理，它为Java项目提供本地跟踪/度量/日志/事件功能。

1. 在SkyWalking发布包中找到skywalking-java文件夹

2. 将-javaagent:/skywalking-java/skywalking-agent.jar添加到JVM参数中。并确保将它添加到-jar参数之前。

   $ java -javaagent:/skywalking-java/skywalking-agent.jar=agent.service_name=myApp,collector.backend_service=localhost:11800 -jar myApp.jar

Java代理的工具包

Java代理提供了用于log4j、log4j2和logback的工具包，用于通过自动注入跟踪上下文的文件报告日志。

logback插件

添加Maven依赖：

<dependency>
	<groupId>org.apache.skywalking</groupId>
	<artifactId>apm-toolkit-logback-1.x</artifactId>
	<version>{project.release.version}</version>
</dependency>
	```

#### 在日志中打印跟踪ID
当您使用`-javaagent`激活SkyWalking跟踪程序时，logback将输出traceId(如果它存在)。如果跟踪器未激活，则输出`TID: N/A`。

* 在logback.xml的模式部分设置`%tid`

	```xml
	<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
            <layout class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.TraceIdPatternLogbackLayout">
                <Pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%tid] [%thread] %-5level %logger{36} -%msg%n</Pattern>
            </layout>
        </encoder>
    </appender>
	```

* 对于MDC，在logback.xml的Pattern部分设置`%X{tid}`

	```xml
	<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
            <layout class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.mdc.TraceIdMDCPatternLogbackLayout">
                <Pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%X{tid}] [%thread] %-5level %logger{36} -%msg%n</Pattern>
            </layout>
        </encoder>
    </appender>
	```

* 支持logback AsyncAppender(MDC也支持)，无需额外配置。请参考下面的logback.xml演示。详细信息:[Logback AsyncAppender](https://logback.qos.ch/manual/appenders.html#AsyncAppender)

	```xml
	<configuration scan="true" scanPeriod=" 5 seconds">
        <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
            <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
                <layout class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.mdc.TraceIdMDCPatternLogbackLayout">
                    <Pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%X{tid}] [%thread] %-5level %logger{36} -%msg%n</Pattern>
                </layout>
            </encoder>
        </appender>
    
        <appender name="ASYNC" class="ch.qos.logback.classic.AsyncAppender">
            <discardingThreshold>0</discardingThreshold>
            <queueSize>1024</queueSize>
            <neverBlock>true</neverBlock>
            <appender-ref ref="STDOUT"/>
        </appender>
    
        <root level="INFO">
            <appender-ref ref="ASYNC"/>
        </root>
    </configuration>
	```

#### 在日志中打印SkyWalking上下文

* 您只需要将模式`%tid`或`%X{tid]}`替换为`%sw_ctx`或`%X{sw_ctx}`。

* 当你使用`-javaagent`激活SkyWalking跟踪器时，如果它存在，logback将输出`SW_CTX: [$serviceName，$instanceName，$traceId，$traceSegmentId，$spanId]`。如果跟踪程序处于非活动状态，则输出为`SW_CTX: N/A`。


#### 完整示例

```xml
<?xml version="1.0" encoding="UTF-8"?>
<!--
  ~ Licensed to the Apache Software Foundation (ASF) under one or more
  ~ contributor license agreements.  See the NOTICE file distributed with
  ~ this work for additional information regarding copyright ownership.
  ~ The ASF licenses this file to You under the Apache License, Version 2.0
  ~ (the "License"); you may not use this file except in compliance with
  ~ the License.  You may obtain a copy of the License at
  ~
  ~      http://www.apache.org/licenses/LICENSE-2.0
  ~
  ~ Unless required by applicable law or agreed to in writing, software
  ~ distributed under the License is distributed on an "AS IS" BASIS,
  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  ~ See the License for the specific language governing permissions and
  ~ limitations under the License.
  -->
<configuration scan="true" scanPeriod=" 5 seconds">

    <appender name="stdout" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
            <layout class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.mdc.TraceIdMDCPatternLogbackLayout">
                <Pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%X{tid}] [%thread] %-5level %logger{36} -%msg%n</Pattern>
            </layout>
        </encoder>
    </appender>

    <appender name="grpc-log" class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.log.GRPCLogClientAppender">
        <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
            <layout class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.mdc.TraceIdMDCPatternLogbackLayout">
                <Pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%X{tid}] [%thread] %-5level %logger{36} -%msg%n</Pattern>
            </layout>
        </encoder>
    </appender>

    <appender name="fileAppender" class="ch.qos.logback.core.FileAppender">
        <file>/tmp/skywalking-logs/logback/e2e-service-provider.log</file>
        <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
            <layout class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.TraceIdPatternLogbackLayout">
                <Pattern>[%sw_ctx] [%level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %logger:%line - %msg%n</Pattern>
            </layout>
        </encoder>
    </appender>

    <root level="INFO">
        <appender-ref ref="grpc-log"/>
        <appender-ref ref="stdout"/>
    </root>
    <logger name="fileLogger" level="INFO">
        <appender-ref ref="fileAppender"/>
    </logger>
</configuration>