分布式应用监控: SkyWalking 快速接入实践

　　分布式应用，会存在各种问题。而要解决这些难题，除了要应用自己做一些监控埋点外，还应该有一些外围的系统进行主动探测，主动发现。

　　APM工具就是干这活的，SkyWalking 是国人开源的一款优秀的APM应用，已成为apache的顶级项目。

　　

　　今天我们就来实践下 SkyWalking 下吧。

　　实践目标： 达到监控现有的几个系统，清楚各调用关系，可以找到出性能问题点。

实践步骤：

　　1. SkyWalking 服务端安装运行；
　　2. 应用端的接入；
　　3. 后台查看效果；
　　4. 分析排查问题；
　　5. 深入了解（如有心情）；

1. SkyWalking 服务端安装

　　下载应用包:

    # 主下载页
    http://skywalking.apache.org/downloads/
    # 点开具体下载地址后进行下载，如：
    wget http://mirrors.tuna.tsinghua.edu.cn/apache/skywalking/6.5.0/apache-skywalking-apm-6.5.0.tar.gz
    

　　解压安装包:

    tar -xzvf apache-skywalking-apm-6.5..tar.gz

　　使用默认配置端口，默认存储方式 h2, 直接启动服务：

    ./bin/startup.sh

　　好产品就是这么简单！

　　现在服务端就启起来了，可以打开后台地址查看(默认是8080端口): http://localhost:8080    界面如下：

　　当然，上面是已存在应用的页面。现在你是看不到任何应用的，因为你还没有接入嘛。

2. 应用端的接入

　　我们只以java应用接入方式实践。

　　直接使用 javaagent 进行启动即可：

    java -javaagent:/root/skywalking/agent/skywalking-agent.jar -Dskywalking.agent.service_name=app1 -Dskywalking.collector.backend_service=localhost: -jar myapp.jar

　　参数说明：

    # 参数解释
    skywalking.agent.service_name: 本应用在skywalking中的名称
    skywalking.collector.backend_service: skywalking 服务端地址，grpc上报地址，默认端口是
    # 上面两个参数也可以使用另外的表现形式
    SW_AGENT_COLLECTOR_BACKEND_SERVICES: 与 skywalking.collector.backend_service 含义相同
    SW_AGENT_NAME: 与 skywalking.agent.service_name 含义相同

　　随便访问几个接口或页面，使监控抓取到数据。

　　再回管理页面，已经看到有节点了。截图如上。

　　现在我们还可以查看各应用之间的关系了!

　　关系清晰吧！一目了然，代码再复杂也不怕了。

　　我们还可以追踪具体链路：

　　只要知道问题发生的时间点，即可以很快定位到发生问题的接口、系统，快速解决。

3. SkyWalking 配置文件

　　如上，我们并没有改任何配置文件，就让系统跑起来了。幸运的同时，我们应该要知道更多！至少配置得知道。

　　config/application.yml : 收集器服务端配置

　　webapp/webapp.yml : 配置 Web 的端口及获取数据的 OAP(Collector)的IP和端口

　　agent/config/agent.config : 配置 Agent 信息，如 Skywalking OAP(Collector)的地址和名称

　　下面是 skywalking 的默认配置，我们可以不用更改就能跑起来一个样例！更改以生产化配置！

config/application.yml

cluster:
  standalone:
  # Please check your ZooKeeper is 3.5+, However, it is also compatible with ZooKeeper 3.4.x. Replace the ZooKeeper 3.5+
  # library the oap-libs folder with your ZooKeeper 3.4.x library.
#  zookeeper:
#    nameSpace: ${SW_NAMESPACE:""}
#    hostPort: ${SW_CLUSTER_ZK_HOST_PORT:localhost:}
#    #Retry Policy
#    baseSleepTimeMs: ${SW_CLUSTER_ZK_SLEEP_TIME:} # initial amount of time to wait between retries
#    maxRetries: ${SW_CLUSTER_ZK_MAX_RETRIES:} # max number of times to retry
#    # Enable ACL
#    enableACL: ${SW_ZK_ENABLE_ACL:false} # disable ACL in default
#    schema: ${SW_ZK_SCHEMA:digest} # only support digest schema
#    expression: ${SW_ZK_EXPRESSION:skywalking:skywalking}
#  kubernetes:
#    watchTimeoutSeconds: ${SW_CLUSTER_K8S_WATCH_TIMEOUT:}
#    namespace: ${SW_CLUSTER_K8S_NAMESPACE:default}
#    labelSelector: ${SW_CLUSTER_K8S_LABEL:app=collector,release=skywalking}
#    uidEnvName: ${SW_CLUSTER_K8S_UID:SKYWALKING_COLLECTOR_UID}
#  consul:
#    serviceName: ${SW_SERVICE_NAME:"SkyWalking_OAP_Cluster"}
#     Consul cluster nodes, example: 10.0.0.1:,10.0.0.2:,10.0.0.3:
#    hostPort: ${SW_CLUSTER_CONSUL_HOST_PORT:localhost:}
#  nacos:
#    serviceName: ${SW_SERVICE_NAME:"SkyWalking_OAP_Cluster"}
#    hostPort: ${SW_CLUSTER_NACOS_HOST_PORT:localhost:}
#  # Nacos Configuration namespace
#    namespace: 'public'
#  etcd:
#    serviceName: ${SW_SERVICE_NAME:"SkyWalking_OAP_Cluster"}
#     etcd cluster nodes, example: 10.0.0.1:,10.0.0.2:,10.0.0.3:
#    hostPort: ${SW_CLUSTER_ETCD_HOST_PORT:localhost:}
core:
  default:
    # Mixed: Receive agent data, Level  aggregate, Level  aggregate
    # Receiver: Receive agent data, Level  aggregate
    # Aggregator: Level  aggregate
    role: ${SW_CORE_ROLE:Mixed} # Mixed/Receiver/Aggregator
    restHost: ${SW_CORE_REST_HOST:0.0.0.0}
    restPort: ${SW_CORE_REST_PORT:}
    restContextPath: ${SW_CORE_REST_CONTEXT_PATH:/}
    gRPCHost: ${SW_CORE_GRPC_HOST:0.0.0.0}
    gRPCPort: ${SW_CORE_GRPC_PORT:}
    downsampling:
      - Hour
      - Day
      - Month
    # Set a timeout on metrics data. After the timeout has expired, the metrics data will automatically be deleted.
    enableDataKeeperExecutor: ${SW_CORE_ENABLE_DATA_KEEPER_EXECUTOR:true} # Turn it off then automatically metrics data delete will be close.
    dataKeeperExecutePeriod: ${SW_CORE_DATA_KEEPER_EXECUTE_PERIOD:} # How often the data keeper executor runs periodically, unit is minute
    recordDataTTL: ${SW_CORE_RECORD_DATA_TTL:} # Unit is minute
    minuteMetricsDataTTL: ${SW_CORE_MINUTE_METRIC_DATA_TTL:} # Unit is minute
    hourMetricsDataTTL: ${SW_CORE_HOUR_METRIC_DATA_TTL:} # Unit is hour
    dayMetricsDataTTL: ${SW_CORE_DAY_METRIC_DATA_TTL:} # Unit is day
    monthMetricsDataTTL: ${SW_CORE_MONTH_METRIC_DATA_TTL:} # Unit is month
    # Cache metric data for  minute to reduce database queries, and if the OAP cluster changes within that minute,
    # the metrics may not be accurate within that minute.
    enableDatabaseSession: ${SW_CORE_ENABLE_DATABASE_SESSION:true}
storage:
#  elasticsearch:
#    nameSpace: ${SW_NAMESPACE:""}
#    clusterNodes: ${SW_STORAGE_ES_CLUSTER_NODES:localhost:}
#    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:}
#    indexReplicasNumber: ${SW_STORAGE_ES_INDEX_REPLICAS_NUMBER:}
#    # Those data TTL settings will override the same settings in core module.
#    recordDataTTL: ${SW_STORAGE_ES_RECORD_DATA_TTL:} # Unit is day
#    otherMetricsDataTTL: ${SW_STORAGE_ES_OTHER_METRIC_DATA_TTL:} # Unit is day
#    monthMetricsDataTTL: ${SW_STORAGE_ES_MONTH_METRIC_DATA_TTL:} # 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:} # Execute the bulk every  requests
#    flushInterval: ${SW_STORAGE_ES_FLUSH_INTERVAL:} # flush the bulk every  seconds whatever the number of requests
#    concurrentRequests: ${SW_STORAGE_ES_CONCURRENT_REQUESTS:} # the number of concurrent requests
#    resultWindowMaxSize: ${SW_STORAGE_ES_QUERY_MAX_WINDOW_SIZE:}
#    metadataQueryMaxSize: ${SW_STORAGE_ES_QUERY_MAX_SIZE:}
#    segmentQueryMaxSize: ${SW_STORAGE_ES_QUERY_SEGMENT_SIZE:}
  h2:
    driver: ${SW_STORAGE_H2_DRIVER:org.h2.jdbcx.JdbcDataSource}
    url: ${SW_STORAGE_H2_URL:jdbc:h2:mem:skywalking-oap-db}
    user: ${SW_STORAGE_H2_USER:sa}
    metadataQueryMaxSize: ${SW_STORAGE_H2_QUERY_MAX_SIZE:}
#  mysql:
#    properties:
#      jdbcUrl: ${SW_JDBC_URL:"jdbc:mysql://localhost:3306/swtest"}
#      dataSource.user: ${SW_DATA_SOURCE_USER:root}
#      dataSource.password: ${SW_DATA_SOURCE_PASSWORD:root@}
#      dataSource.cachePrepStmts: ${SW_DATA_SOURCE_CACHE_PREP_STMTS:true}
#      dataSource.prepStmtCacheSize: ${SW_DATA_SOURCE_PREP_STMT_CACHE_SQL_SIZE:}
#      dataSource.prepStmtCacheSqlLimit: ${SW_DATA_SOURCE_PREP_STMT_CACHE_SQL_LIMIT:}
#      dataSource.useServerPrepStmts: ${SW_DATA_SOURCE_USE_SERVER_PREP_STMTS:true}
#    metadataQueryMaxSize: ${SW_STORAGE_MYSQL_QUERY_MAX_SIZE:}
receiver-sharing-server:
  default:
receiver-register:
  default:
receiver-trace:
  default:
    bufferPath: ${SW_RECEIVER_BUFFER_PATH:../trace-buffer/}  # Path to trace buffer files, suggest to use absolute path
    bufferOffsetMaxFileSize: ${SW_RECEIVER_BUFFER_OFFSET_MAX_FILE_SIZE:} # Unit is MB
    bufferDataMaxFileSize: ${SW_RECEIVER_BUFFER_DATA_MAX_FILE_SIZE:} # Unit is MB
    bufferFileCleanWhenRestart: ${SW_RECEIVER_BUFFER_FILE_CLEAN_WHEN_RESTART:false}
    sampleRate: ${SW_TRACE_SAMPLE_RATE:} # The sample rate precision is /.  means % sample in default.
    slowDBAccessThreshold: ${SW_SLOW_DB_THRESHOLD:default:,mongodb:} # The slow database access thresholds. Unit ms.
receiver-jvm:
  default:
receiver-clr:
  default:
service-mesh:
  default:
    bufferPath: ${SW_SERVICE_MESH_BUFFER_PATH:../mesh-buffer/}  # Path to trace buffer files, suggest to use absolute path
    bufferOffsetMaxFileSize: ${SW_SERVICE_MESH_OFFSET_MAX_FILE_SIZE:} # Unit is MB
    bufferDataMaxFileSize: ${SW_SERVICE_MESH_BUFFER_DATA_MAX_FILE_SIZE:} # Unit is MB
    bufferFileCleanWhenRestart: ${SW_SERVICE_MESH_BUFFER_FILE_CLEAN_WHEN_RESTART:false}
istio-telemetry:
  default:
envoy-metric:
  default:
#    alsHTTPAnalysis: ${SW_ENVOY_METRIC_ALS_HTTP_ANALYSIS:k8s-mesh}
#receiver_zipkin:
#  default:
#    host: ${SW_RECEIVER_ZIPKIN_HOST:0.0.0.0}
#    port: ${SW_RECEIVER_ZIPKIN_PORT:}
#    contextPath: ${SW_RECEIVER_ZIPKIN_CONTEXT_PATH:/}
query:
  graphql:
    path: ${SW_QUERY_GRAPHQL_PATH:/graphql}
alarm:
  default:
telemetry:
  none:
configuration:
  none:
#  apollo:
#    apolloMeta: http://106.12.25.204:8080
#    apolloCluster: default
#    # apolloEnv: # defaults to null
#    appId: skywalking
#    period:
#  nacos:
#    # Nacos Server Host
#    serverAddr: 127.0.0.1
#    # Nacos Server Port
#    port:
#    # Nacos Configuration Group
#    group: 'skywalking'
#    # Nacos Configuration namespace
#    namespace: ''
#    # Unit seconds, sync period. Default fetch every  seconds.
#    period :
#    # the name of current cluster, set the name if you want to upstream system known.
#    clusterName: "default"
#  zookeeper:
#    period :  # Unit seconds, sync period. Default fetch every  seconds.
#    nameSpace: /default
#    hostPort: localhost:
#    #Retry Policy
#    baseSleepTimeMs:  # initial amount of time to wait between retries
#    maxRetries:  # max number of times to retry
#  etcd:
#    period :  # Unit seconds, sync period. Default fetch every  seconds.
#    group :  'skywalking'
#    serverAddr: localhost:
#    clusterName: "default"
#  consul:
#    # Consul host and ports, separated by comma, e.g. 1.2.3.4:,2.3.4.5:
#    hostAndPorts: ${consul.address}
#    # Sync period in seconds. Defaults to  seconds.
#    period: 

#exporter:
#  grpc:
#    targetHost: ${SW_EXPORTER_GRPC_HOST:127.0.0.1}
#    targetPort: ${SW_EXPORTER_GRPC_PORT:}
    

webapp/webapp.yml

server:
  port: 

collector:
  path: /graphql
  ribbon:
    ReadTimeout:
    # Point to all backend's restHost:restPort, split by ,
    listOfServers: 127.0.0.1:

agent/config/agent.config

# The agent namespace
# agent.namespace=${SW_AGENT_NAMESPACE:default-namespace}

# The service name in UI
agent.service_name=${SW_AGENT_NAME:Your_ApplicationName}

# The number of sampled traces per  seconds
# Negative number means sample traces as many as possible, most likely %
# agent.sample_n_per_3_secs=${SW_AGENT_SAMPLE:-}

# Authentication active is based on backend setting, see application.yml for more details.
# agent.authentication = ${SW_AGENT_AUTHENTICATION:xxxx}

# The max amount of spans in a single segment.
# Through this config item, skywalking keep your application memory cost estimated.
# agent.span_limit_per_segment=${SW_AGENT_SPAN_LIMIT:}

# Ignore the segments if their operation names end with these suffix.
# agent.ignore_suffix=${SW_AGENT_IGNORE_SUFFIX:.jpg,.jpeg,.js,.css,.png,.bmp,.gif,.ico,.mp3,.mp4,.html,.svg}

# If true, skywalking agent will save all instrumented classes files in `/debugging` folder.
# Skywalking team may ask for these files in order to resolve compatible problem.
# agent.is_open_debugging_class = ${SW_AGENT_OPEN_DEBUG:true}

# The operationName max length
# agent.operation_name_threshold=${SW_AGENT_OPERATION_NAME_THRESHOLD:}

# Backend service addresses.
collector.backend_service=${SW_AGENT_COLLECTOR_BACKEND_SERVICES:127.0.0.1:}

# Logging file_name
logging.file_name=${SW_LOGGING_FILE_NAME:skywalking-api.log}

# Logging level
logging.level=${SW_LOGGING_LEVEL:DEBUG}

# Logging dir
# logging.dir=${SW_LOGGING_DIR:""}

# Logging max_file_size, default:  *  *  =
# logging.max_file_size=${SW_LOGGING_MAX_FILE_SIZE:}

# The max history log files. When rollover happened, if log files exceed this number,
# then the oldest file will be delete. Negative or zero means off, by default.
# logging.max_history_files=${SW_LOGGING_MAX_HISTORY_FILES:-}

# mysql plugin configuration
# plugin.mysql.trace_sql_parameters=${SW_MYSQL_TRACE_SQL_PARAMETERS:false}

4. SkyWalking 架构

　　来自官网的图片，感受一下！无须细说，大概原理就是： 针对各种不同客户端实现不同的指标采集，统一通过grpc/http发送到apm服务端，然后经过分析引擎后存储到es/h2/mysql等等存储系统，最后由前端通过查询引擎进行展现。

5. 可以用来干啥

　　发现系统耗时或者说瓶颈在哪里。

　　发现各系统之间的调用关系。

　　监控服务异常。

　　排查系统故障。

6. 其他存储系统接入

　　h2只是一个内存存储系统，其目的是为了让你能够快速验证快速响应，它还没有强大到足以支撑线上系统运行。

　　所以，线上一定得选用某个更可靠存储。

　　一般地，ES会是个不错的选择，一来它以搜索速度著称而这正好符合后台查询的需求，二来es是分布式存储，可以避免一定的大数据量问题。

　　mysql: 一般地对普通开发同学友好，且单机mysql容易搭建。

　　tidb: 与mysql协议完全兼容，分布式存储。

　　配置方法如demo所示。。。