最近在学习springcloud阿里巴巴的使用，单机使用nacos启动时没有问题，修改了配置之后启动报错，如下
org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:156)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:544)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:744)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:391)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:312)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1204)
at com.alibaba.nacos.Nacos.main(Nacos.java:35)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49)
at org.springframework.boot.loader.Launcher.launch(Launcher.java:107)
at org.springframework.boot.loader.Launcher.launch(Launcher.java:58)
at org.springframework.boot.loader.PropertiesLauncher.main(PropertiesLauncher.java:467)
Caused by: org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:124)
at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.<init>(TomcatWebServer.java:86)
at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getTomcatWebServer(TomcatServletWebServerFactory.java:416)
at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getWebServer(TomcatServletWebServerFactory.java:180)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:180)
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:153)
... 16 common frames omitted贴出已经修改的配置文件，cluster.conf和application.properties
cluster.conf如下
#2022-09-09T17:19:05.745
127.0.0.1:8845
127.0.0.1:8846
127.0.0.1:8847
application.properties如下，其他不需要修改的地方没有复制进来
#*************** Spring Boot Related Configurations ***************#
### Default web context path:
server.servlet.contextPath=/nacos
### Default web server port:
server.port=8845
#*************** Network Related Configurations ***************#
### If prefer hostname over ip for Nacos server addresses in cluster.conf:
# nacos.inetutils.prefer-hostname-over-ip=false
### Specify local server's IP:
# nacos.inetutils.ip-address=
#*************** Config Module Related Configurations ***************#
### If use MySQL as datasource:
spring.datasource.platform=mysql
### Count of DB:
# db.num=1
### Connect URL of DB:
db.url.0=jdbc:mysql://127.0.0.1:3306/nacos?characterEncoding=utf8&connectTimeout=1000&socketTimeout=3000&autoReconnect=true&useUnicode=true&useSSL=false&serverTimezone=UTC
db.user.0=root
db.password.0=password
### Connection pool configuration: hikariCP
db.pool.config.connectionTimeout=30000
db.pool.config.validationTimeout=10000
db.pool.config.maximumPoolSize=20
db.pool.config.minimumIdle=2因为是看着视频一步一步改的，然后视频里老师成功了，我运行失败了，网上找了很多地方都没有解答，都是说把集群改成单机启动就可以了，但是我要的就是集群启动。然后看了一下nacos.log的最后几行日志，提示jdbc连接有问题，如下
Caused by: java.lang.RuntimeException: java.lang.RuntimeException: [db-load-error]load jdbc.properties error
at com.alibaba.nacos.config.server.service.datasource.DynamicDataSource.getDataSource(DynamicDataSource.java:58)
at com.alibaba.nacos.config.server.service.repository.extrnal.ExternalStoragePersistServiceImpl.init(ExternalStoragePersistServiceImpl.java:138)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleElement.invoke(InitDestroyAnnotationBeanPostProcessor.java:363)
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor$LifecycleMetadata.invokeInitMethods(InitDestroyAnnotationBeanPostProcessor.java:307)
at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:136)
... 158 common frames omitted
Caused by: java.lang.RuntimeException: [db-load-error]load jdbc.properties error
at com.alibaba.nacos.config.server.service.datasource.ExternalDataSourceServiceImpl.init(ExternalDataSourceServiceImpl.java:107)
at com.alibaba.nacos.config.server.service.datasource.DynamicDataSource.getDataSource(DynamicDataSource.java:53)
... 166 common frames omitted方向确认，进mysql测试url账号密码一切正常，但是发现配置文件有个容易忽略的地方没有修改，相信细心的同学已经发现了，就是application.properties中的Count of DB，如下
### Count of DB:
# db.num=1
### Connect URL of DB:
db.url.0=jdbc:mysql://127.0.0.1:3306/nacos?characterEncoding=utf8&connectTimeout=1000&socketTimeout=3000&autoReconnect=true&useUnicode=true&useSSL=false&serverTimezone=UTC
db.user.0=root
db.password.0=password把db.num=1 前面的注释删掉，重新启动，运行成功！！！！
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