目的
為了學習skywalking源碼的設計，以及更好的了解內部原理，對系統進行擴展，優化。
參考
github上skywalking官方教程:https://github.com/apache/skywalking/blob/master/docs/en/guides/How-to-build.md
SkyWalking 6.x 源碼分析 —— 調試環境搭建【芋道源碼】:http://www.iocoder.cn/SkyWalking/6/build-debugging-environment/
環境准備
操作系統: macOS 10.14.1
skywalking源碼版本: github上6.6.0之后的master分支(2020-1-29)
IDE: intelliJ IDEA
jdk: 1.8
maven: maven 3
構建項目
1.clone代碼
git clone https://github.com/apache/skywalking.git
遇到的問題
(1) 問題：clone代碼失敗：
解決辦法：配置host，可加快網速
219.76.4.4 github-cloud.s3.amazonaws.com
192.30.253.112 github.com
151.101.185.194 github.global.ssl.fastly.net
2.選擇maven方式導入skywalking源碼到IDEA
3.執行git命令
git submodule init
4.執行git命令
git submodule update
這兩步的目的是獲取skywalking子模塊的源碼，子模塊包括apm-network、query-graphql-plugin、skywalking-ui、e2e-ttl-es，具體的依賴信息可查看/.gitmodules文件
[submodule "apm-protocol/apm-network/src/main/proto"]
path = apm-protocol/apm-network/src/main/proto
url = https://github.com/apache/skywalking-data-collect-protocol.git
[submodule "oap-server/server-query-plugin/query-graphql-plugin/src/main/resources/query-protocol"]
path = oap-server/server-query-plugin/query-graphql-plugin/src/main/resources/query-protocol
url = https://github.com/apache/skywalking-query-protocol.git
[submodule "skywalking-ui"]
path = skywalking-ui
url = https://github.com/apache/skywalking-rocketbot-ui.git
[submodule "test/e2e/e2e-ttl/e2e-ttl-es/src/main/proto"]
path = test/e2e/e2e-ttl/e2e-ttl-es/src/main/proto
url = https://github.com/apache/skywalking-data-collect-protocol.git
- 【敲黑板】該步驟非常重要，不完整執行成功，后續的編譯會失敗。
- git submodule update執行很慢，還可能中途中斷，但是執行的過程中不要手動中斷命令的執行，等10分鍾看結果，不然文件可能只下載了一部分，導致莫名其妙的問題。
遇到的問題
(1)git submodule update失敗
terrydeMacBook-Pro:skywalking-terry terry$ git submodule init
terrydeMacBook-Pro:skywalking-terry terry$ git submodule update
Submodule path 'oap-server/server-query-plugin/query-graphql-plugin/src/main/resources/query-protocol': checked out '6fc96650acc7f539fcdf6d51648525ce93e5fa1a'
fatal: Needed a single revision
Unable to find current revision in submodule path 'skywalking-ui'
解決辦法：
參考：https://www.cnblogs.com/ligun123/p/4139883.html
刪除skywalking-ui目錄，再執行git submodule update，將會出現如下：
terrydembp:skywalking-github terry$ git submodule update
remote: Enumerating objects: 14, done.
remote: Counting objects: 100% (14/14), done.
remote: Compressing objects: 100% (14/14), done.
remote: Total 4370 (delta 2), reused 3 (delta 0), pack-reused 4356
Receiving objects: 100% (4370/4370), 13.76 MiB | 36.00 KiB/s, done.
Resolving deltas: 100% (2575/2575), done.
From https://github.com/apache/skywalking-rocketbot-ui
* [new branch] develop -> origin/develop
* [new branch] master -> origin/master
* [new tag] v0.9.0 -> v0.9.0
* [new tag] v1.0.0 -> v1.0.0
* [new tag] v1.0.1 -> v1.0.1
* [new tag] v1.0.2 -> v1.0.2
* [new tag] v1.0.3 -> v1.0.3
* [new tag] v6.1.0 -> v6.1.0
* [new tag] v6.2.0 -> v6.2.0
* [new tag] v6.3.0 -> v6.3.0
* [new tag] v6.4.0 -> v6.4.0
* [new tag] v6.5.0 -> v6.5.0
* [new tag] v6.6.0 -> v6.6.0
Submodule path 'skywalking-ui': checked out '9ad81a05a2f2969420c1f75769c2b4def42819e4'
Submodule path 'test/e2e/e2e-ttl/e2e-ttl-es/src/main/proto': checked out '7b244ff7ec350910295eee85633e02d92a6f6b1c'
5.執行mvn命令
./mvnw clean package -DskipTests
這一步執行時間長短和網速有關系，編譯過兩次，一次14min、一次1h
執行情況示例：
terrydembp:skywalking-github terry$ ./mvnw clean package -DskipTests
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 50710 100 50710 0 0 20994 0 0:00:02 0:00:02 --:--:-- 20997
[INFO] Scanning for projects...
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order:
[INFO]
[INFO] apm [pom]
[INFO] apm-commons [pom]
省略許多行......
省略許多行......
省略許多行......
遇到的問題
(1) ./mvnw clean package -DskipTests無法編譯
原因：開了vpn，原以為【翻qiang】會快很多，沒想到開了VPN，反而下載不了需要的插件。
解決辦法：關閉vpm
(2)執行失敗，提示缺少部分類，例如缺少類KeyStringValuePair.java
[ERROR] /Users/terry/Gits/agent/skywalking/skywalking-github/apm-protocol/apm-network/src/main/java/org/apache/skywalking/apm/network/trace/component/command/TraceIgnoreCommand.java:[39,48] 找不到符號
[ERROR] 符號: 變量 KeyStringValuePair
[ERROR] 位置: 類 org.apache.skywalking.apm.network.trace.component.command.TraceIgnoreCommand
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException
[ERROR]
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR] mvn <goals> -rf :apm-network
可能是因為git submodule沒有更新到submodule，解決辦法是：找到上面提到的項目根目錄下的/.gitmodules文件，查看submodule對應的path路徑，看是否完整更新下來的源碼。
可以刪除這幾個目錄，然后執行git submodule init、git submodule update，重新更新submodule的文件。
執行成功的結果：
[INFO] configuration-consul ............................... SUCCESS [ 2.216 s]
[INFO] server-bootstrap ................................... SUCCESS [ 4.166 s]
[INFO] server-starter ..................................... SUCCESS [01:27 min]
[INFO] server-starter-es7 ................................. SUCCESS [ 8.393 s]
[INFO] apm-webapp ......................................... SUCCESS [07:15 min]
[INFO] apache-skywalking-apm .............................. SUCCESS [ 45.532 s]
[INFO] apache-skywalking-apm-es7 .......................... SUCCESS [ 22.466 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 01:01 h
[INFO] Finished at: 2020-01-29T13:03:28+08:00
6.最終在disk目錄下生成了文件：
dist/apache-skywalking-apm-bin.tar.gz
dist/apache-skywalking-apm-bin-es7.tar.gz
這些包和官方的release版本的包是一樣的，后續可以自己修改源碼進行編譯、構建、部署。
7.生成源碼：
grpc-java and java folders in apm-protocol/apm-network/target/generated-sources/protobuf
grpc-java and java folders in oap-server/server-core/target/generated-sources/protobuf
grpc-java and java folders in oap-server/server-receiver-plugin/receiver-proto/target/generated-sources/protobuf
grpc-java and java folders in oap-server/exporter/target/generated-sources/protobuf
grpc-java and java folders in oap-server/server-configuration/grpc-configuration-sync/target/generated-sources/protobuf
antlr4 folder in oap-server/oal-grammar/target/generated-sources
根據官網找到上面的文件目錄，
右鍵--->Mark Directory As --->Generated Rources Root
文件夾會由黃色變成藍色
啟動：
啟動OapServer
執行org.apache.skywalking.oap.server.starter.OAPServerStartUp#main方法，啟動server。
注意
- 6.6.0默認是用es7作為storage module，所以需要部署es7；
如果想用其他storage module，則可以修改/oap-server/server-bootstrap/src/main/resources/application.yml目錄下的storage節點的配置。然后rebuild一下該文件，重新編譯，在重新啟動即可。
我采用的的是ES6，修改skywalking的配置如下，啟動ES后，再啟動OapServer
storage:
elasticsearch:
nameSpace: ${SW_NAMESPACE:""}
clusterNodes: ${SW_STORAGE_ES_CLUSTER_NODES:localhost:9200}
protocol: ${SW_STORAGE_ES_HTTP_PROTOCOL:"http"}
#trustStorePath: ${SW_SW_STORAGE_ES_SSL_JKS_PATH:"../es_keystore.jks"}
#trustStorePass: ${SW_SW_STORAGE_ES_SSL_JKS_PASS:""}
user: ${SW_ES_USER:""}
password: ${SW_ES_PASSWORD:""}
indexShardsNumber: ${SW_STORAGE_ES_INDEX_SHARDS_NUMBER:2}
indexReplicasNumber: ${SW_STORAGE_ES_INDEX_REPLICAS_NUMBER:0}
# Those data TTL settings will override the same settings in core module.
recordDataTTL: ${SW_STORAGE_ES_RECORD_DATA_TTL:7} # Unit is day
otherMetricsDataTTL: ${SW_STORAGE_ES_OTHER_METRIC_DATA_TTL:45} # Unit is day
monthMetricsDataTTL: ${SW_STORAGE_ES_MONTH_METRIC_DATA_TTL:18} # Unit is month
# Batch process setting, refer to https://www.elastic.co/guide/en/elasticsearch/client/java-api/5.5/java-docs-bulk-processor.html
bulkActions: ${SW_STORAGE_ES_BULK_ACTIONS:1000} # Execute the bulk every 1000 requests
flushInterval: ${SW_STORAGE_ES_FLUSH_INTERVAL:10} # flush the bulk every 10 seconds whatever the number of requests
concurrentRequests: ${SW_STORAGE_ES_CONCURRENT_REQUESTS:2} # the number of concurrent requests
resultWindowMaxSize: ${SW_STORAGE_ES_QUERY_MAX_WINDOW_SIZE:10000}
metadataQueryMaxSize: ${SW_STORAGE_ES_QUERY_MAX_SIZE:5000}
segmentQueryMaxSize: ${SW_STORAGE_ES_QUERY_SEGMENT_SIZE:200}
profileTaskQueryMaxSize: ${SW_STORAGE_ES_QUERY_PROFILE_TASK_SIZE:200}
advanced: ${SW_STORAGE_ES_ADVANCED:""}
# elasticsearch7:
# nameSpace: ${SW_NAMESPACE:""}
# clusterNodes: ${SW_STORAGE_ES_CLUSTER_NODES:localhost:9200}
# protocol: ${SW_STORAGE_ES_HTTP_PROTOCOL:"http"}
# #trustStorePath: ${SW_SW_STORAGE_ES_SSL_JKS_PATH:"../es_keystore.jks"}
# #trustStorePass: ${SW_SW_STORAGE_ES_SSL_JKS_PASS:""}
# user: ${SW_ES_USER:""}
# password: ${SW_ES_PASSWORD:""}
# indexShardsNumber: ${SW_STORAGE_ES_INDEX_SHARDS_NUMBER:2}
# indexReplicasNumber: ${SW_STORAGE_ES_INDEX_REPLICAS_NUMBER:0}
# # Those data TTL settings will override the same settings in core module.
# recordDataTTL: ${SW_STORAGE_ES_RECORD_DATA_TTL:7} # Unit is day
# otherMetricsDataTTL: ${SW_STORAGE_ES_OTHER_METRIC_DATA_TTL:45} # Unit is day
# monthMetricsDataTTL: ${SW_STORAGE_ES_MONTH_METRIC_DATA_TTL:18} # Unit is month
# # Batch process setting, refer to https://www.elastic.co/guide/en/elasticsearch/client/java-api/5.5/java-docs-bulk-processor.html
# bulkActions: ${SW_STORAGE_ES_BULK_ACTIONS:1000} # Execute the bulk every 1000 requests
# flushInterval: ${SW_STORAGE_ES_FLUSH_INTERVAL:10} # flush the bulk every 10 seconds whatever the number of requests
# concurrentRequests: ${SW_STORAGE_ES_CONCURRENT_REQUESTS:2} # the number of concurrent requests
# resultWindowMaxSize: ${SW_STORAGE_ES_QUERY_MAX_WINDOW_SIZE:10000}
# metadataQueryMaxSize: ${SW_STORAGE_ES_QUERY_MAX_SIZE:5000}
# segmentQueryMaxSize: ${SW_STORAGE_ES_QUERY_SEGMENT_SIZE:200}
# advanced: ${SW_STORAGE_ES_ADVANCED:""}
查看ES索引
訪問http://localhost:9200/_cat/indices
查看ES索引可以檢驗skywalking初始化數據是否成功
啟動webApp
執行org.apache.skywalking.apm.webapp.ApplicationStartUp方法
驗證
訪問http://127.0.0.1:8080/
啟動普通java應用，驗證鏈路追蹤
配置應用的VM參數如下，再運行應用：
-Dskywalking.agent.service_name=skywalking-test-local -Dskywalking.collector.backend_service=127.0.0.1:11800 -javaagent:/Users/terry/Gits/agent/skywalking-bin/6.6.0/apache-skywalking-apm-bin/agent/skywalking-agent.jar
驗證
訪問一個springmvc的請求localhost:8082/a_testSysLog
參考skywalking
