Spring cloud Alibaba: multi file loading and sharing configuration of Nacos configuration

1, Load multiple configurations

We already know that the correspondence between the Spring application and the configuration content in Nacos is controlled by the following three parameters:

• spring.cloud.nacos.config.prefix
• spring.cloud.nacos.config.file-extension
• spring.cloud.nacos.config.group

By default, Data ID=${spring.application.name}.properties, group = default will be loaded_ Group configuration.

Suppose there is such a requirement: we want to do unified configuration management for the Actuator module and log output of all applications. Therefore, we hope that the configuration of the Actuator module can be placed in a separate configuration file actuator.properties, and the configuration of log output can be placed in a separate configuration file log.properties. By splitting these two types of configuration content, we hope to achieve shared loading and unified management of configuration.

1. Solutions

Step 1: create data id = actor.properties, group = Default in Nacos_ Group and Data ID=log.properties, Group=DEFAULT_GROUP configuration content.

We will load these three configuration files here

Step 2: in the Spring Cloud application, configure the two configuration contents to be loaded by using the spring.cloud.nacos.config.ext-config parameter, such as:

• properties format

server.port=9004
spring.application.name=config
spring.cloud.nacos.discovery.server-addr=192.168.31.100:8848
spring.cloud.nacos.config.server-addr=192.168.31.100:8848
spring.cloud.nacos.config.file-extension=yaml
spring.cloud.nacos.config.ext-config[0].data-id=actuator.properties
spring.cloud.nacos.config.ext-config[0].group=DEFAULT_GROUP
spring.cloud.nacos.config.ext-config[0].refresh=true
spring.cloud.nacos.config.ext-config[1].data-id=log.properties
spring.cloud.nacos.config.ext-config[1].group=DEFAULT_GROUP
spring.cloud.nacos.config.ext-config[1].refresh=true

• yml format

server:
  port: 9004
spring:
  application:
    name: config
  cloud:
    nacos:
      config:
        ext-config:
        - data-id: actuator.properties
          group: DEFAULT_GROUP
          refresh: true
        - data-id: log.properties
          group: DEFAULT_GROUP
          refresh: true
        file-extension: yaml
        server-addr: 192.168.31.100:8848
      discovery:
        server-addr: 192.168.31.100:8848

As you can see, the spring.cloud.nacos.config.ext-config configuration is an array List type. Each configuration contains three parameters: data ID, group and refresh; The first two do not need to be repeated. They correspond to the configurations created in Nacos. The refresh parameter controls that the contents in this configuration file support automatic refresh. By default, only the default loaded configurations will be refreshed automatically. For these extended configurations, the automatic refresh will be realized when the settings need to be configured.

Note: this configuration must be loaded in the bootstrap.properties file

Step 3: start the test

Request address: 127.0.0.1:9004/config/info

Response result:
config-test.yml:there is test version=1.0
actuator.properties:"hello actuator"
log.properties:"hello log"

2, Shared configuration

By loading multiple configurations above, we can actually share configurations for different applications. However, Nacos also provides another convenient configuration method. For example, the following settings are equivalent to the configuration content used above:

spring.cloud.nacos.config.shared-dataids=actuator.properties,log.properties
spring.cloud.nacos.config.refreshable-dataids=actuator.properties,log.properties

• The spring.cloud.nacos.config.shared-dataids parameter is used to configure the data IDs of multiple shared configurations, which are separated by commas
• The spring.cloud.nacos.config.refreshable-dataids parameter is used to define which shared configuration data IDS can be refreshed dynamically in the application when the configuration changes, and multiple data IDs are separated by commas. If there is no explicit configuration, all shared configurations do not support dynamic refresh by default

3, Configure load priority

When we load multiple configurations, if the same key exists, we need to deeply understand the priority relationship of configuration loading.

When using Nacos configuration, there are three main types of configuration:

• A: Share configuration defined through spring.cloud.nacos.config.shared-dataids
• B: Load configuration defined through spring. Cloud. Nacos. Config. Ext config [n]
• C: Configurations spliced by internal rules (spring.cloud.nacos.config.prefix, spring.cloud.nacos.config.file-extension, spring.cloud.nacos.config.group)

Modify the bootstrap.properties configuration file

server.port=9004
spring.application.name=config
spring.cloud.nacos.discovery.server-addr=192.168.31.100:8848
spring.cloud.nacos.config.server-addr=192.168.31.100:8848
spring.cloud.nacos.config.file-extension=yaml
spring.cloud.nacos.config.ext-config[0].data-id=actuator.properties
spring.cloud.nacos.config.ext-config[0].group=DEFAULT_GROUP
spring.cloud.nacos.config.ext-config[0].refresh=true
#spring.cloud.nacos.config.ext-config[1].data-id=log.properties
#spring.cloud.nacos.config.ext-config[1].group=DEFAULT_GROUP
#spring.cloud.nacos.config.ext-config[1].refresh=true

spring.cloud.nacos.config.shared-dataids=log.properties
spring.cloud.nacos.config.refreshable-dataids=log.properties

According to the above configuration, the application will load three different configuration files. When starting the application, you will see the following output in the log:

2021-10-25 16:31:20.897  INFO 14456 --- [           main] c.a.c.n.c.NacosPropertySourceBuilder     : Loading nacos data, dataId: 'log.properties', group: 'DEFAULT_GROUP'
2021-10-25 16:31:20.902  INFO 14456 --- [           main] c.a.c.n.c.NacosPropertySourceBuilder     : Loading nacos data, dataId: 'actuator.properties', group: 'DEFAULT_GROUP'
2021-10-25 16:31:20.910  INFO 14456 --- [           main] c.a.c.n.c.NacosPropertySourceBuilder     : Loading nacos data, dataId: 'config-test.yaml', group: 'DEFAULT_GROUP'

Conclusion: the configuration loaded later will overwrite the configuration loaded earlier, so the priority relationship is: a < B < C