Table of contents
Using nacos as the configuration center is actually treating nacos as a server and each microservice as a client. We store the configuration files of each microservice on nacos, and then each microservice pulls the configuration from nacos. Can.
Use of configuration center:
During this process, an error is reported when starting the main program:
异常：java.lang.IllegalArgumentException: Could not resolve placeholder 'spring.datasource.druid.username' in value "${spring.datasource.druid.username}"
2023-05-17 19:33:57.875 ERROR 12820 --- [ main] o.s.boot.SpringApplication : Application run failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSourceConfig': Injection of autowired dependencies failed; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'spring.datasource.druid.username' in value "${spring.datasource.druid.username}"
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:405) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1431) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:619) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:955) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918) ~[spring-context-5.3.22.jar:5.3.22]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.22.jar:5.3.22]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.6.11.jar:2.6.11]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:745) ~[spring-boot-2.6.11.jar:2.6.11]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:420) ~[spring-boot-2.6.11.jar:2.6.11]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:307) ~[spring-boot-2.6.11.jar:2.6.11]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1317) ~[spring-boot-2.6.11.jar:2.6.11]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306) ~[spring-boot-2.6.11.jar:2.6.11]
at com.buba.UserApp.main(UserApp.java:17) ~[classes/:na]
Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'spring.datasource.druid.username' in value "${spring.datasource.druid.username}"
at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:180) ~[spring-core-5.3.22.jar:5.3.22]
at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126) ~[spring-core-5.3.22.jar:5.3.22]
at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:239) ~[spring-core-5.3.22.jar:5.3.22]
at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:210) ~[spring-core-5.3.22.jar:5.3.22]
at org.springframework.context.support.PropertySourcesPlaceholderConfigurer.lambda$processProperties$0(PropertySourcesPlaceholderConfigurer.java:191) ~[spring-context-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.support.AbstractBeanFactory.resolveEmbeddedValue(AbstractBeanFactory.java:936) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1332) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1311) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:656) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:639) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119) ~[spring-beans-5.3.22.jar:5.3.22]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399) ~[spring-beans-5.3.22.jar:5.3.22]
... 17 common frames omitted2023-05-17 19:33:57.875 ERROR 12820 --- [ main] o.s.boot.SpringApplication : Application run failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSourceConfig': Injection of autowired dependencies failed; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'spring.datasource.druid.username' in value "${spring.datasource.druid.username}"
at
This error is caused by the inability of springboot to parse ${XXXXXXXX} in the application.properties configuration file when it starts.
yml configuration file before error reporting:
spring:
application:
name: user-server
cloud:
nacos:
discovery:
username: nacos
password: nacos
server-addr: 192.168.177.129:8848
config:
server-addr: 192.168.177.129:8848
file-extension: yamlHow to solve it?
spring:
application:
name: user-server
cloud:
nacos:
discovery:
username: nacos
password: nacos
server-addr: 192.168.177.129:8848
config:
username: nacos
password: nacos
server-addr: 192.168.177.129:8848
file-extension: yaml
In the previous solution, the Nacos page did not log in, so the authentication was set up, so the configuration center also needs it.
After correcting the configuration file, the springboot application can start normally. This is also one of the mistakes when using configuration files. So when we write properties configuration, we need to pay attention to:
1. The attribute name should correspond to the official document, case-sensitive
2. When using ${propertyName} to refer to other properties, the property name should also be correct
3. If there is an exception that the placeholder cannot be parsed, first check whether the attribute name in the placeholder is correct