Detailed introduction to the usage of Nacos configuration center

         The last article introduced Nacos Usage as a registry , besides ,Nacos It can also be used as a configuration center , Then this article will introduce Nacos As the basic usage of configuration center , First, let's understand why we need to use the configuration center .

One 、 Why configure the center ：

Before there is no configuration center , The traditional application configuration has the following pain points ：

（1） Adopt local static configuration , There's no guarantee of real-time ： Modifying the configuration is not flexible and requires a long test release cycle , Unable to notify the client as soon as possible , Some configurations require high real-time performance , For example, the configuration of active / standby switchover or the configuration needs to be modified in case of failure , At this time, configure through traditional static configuration or republishing , Then the response speed is very slow , Business risks are very high

（2） Easy to cause production accidents ： For example, when publishing , It is easy to bring the configuration of the test environment to production , Cause production accidents .

（3） The configuration is messy and the format is not standard ： Some use properties Format , Some use xml Format , There are still deposits DB, Teams tend to make their own wheels , There are various methods .

（4） The configuration lacks security audit 、 version control 、 Configure permission control function ： who ？ At what time ？ What configuration has been modified ？ There is no way to trace , If something goes wrong, you can't rollback to the previous version in time ; Unable to authenticate and authorize the release of configuration changes , Everyone can modify and publish the configuration .

         The configuration center is different from the traditional way that the configuration information is distributed to all corners of the system , Centralized and unified management of configuration files in the system , There is no need to manage individual servers one by one . So what's the advantage of doing this ？

（1） Through the configuration center , It can standardize the configuration 、 Unified format

（2） When the configuration information changes , Changes take effect in real time , There is no need to restart the server , Can automatically perceive the corresponding changes , And send the new changes to the corresponding procedures , Respond quickly to change . For example, a function is only for users in a certain region , There is also a function that is only available during the promotion period , After using the configuration center, only relevant personnel need to dynamically adjust parameters in the configuration center , Basically, you can adjust the corresponding business in real time or quasi real time .

（3） The audit function can also trace the problem

Two 、Nacos Use of configuration center ：

         There are three main solutions for configuration center in microservices ：Nacos、Apollo、Config+Bus, However, this article mainly introduces Nacos Usage as configuration center , Readers who are interested in the other two ways should check online by themselves

1、Springboot Integrate Nacos Configuration center ：

（1） First, we declare the version information of the project ：

<properties>
    <spring-boot.version>2.3.2.RELEASE</spring-boot.version>
    <spring-cloud.version>Hoxton.SR9</spring-cloud.version>
    <spring-cloud-alibaba.version>2.2.6.RELEASE</spring-cloud-alibaba.version>
</properties>

<!--   Only declare dependencies , Do not introduce dependencies  -->
<dependencyManagement>
    <dependencies>
        <!--  Statement springBoot edition  -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-dependencies</artifactId>
            <version>${spring-boot.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
        <!--  Statement springCloud edition  -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>${spring-cloud.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
        <!--  Statement  springCloud Alibaba  edition  -->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-alibaba-dependencies</artifactId>
            <version>${spring-cloud-alibaba.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

（2） add to nacos Configuration center maven rely on ：

<!-- SpringCloud Ailibaba Nacos Config -->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
</dependency>

（3） stay application.properties Add... To the file nacos Configuration center related configuration ：

spring.profiles.active=dev
spring.application.name=cloud-producer-server
server.port=8080

# nacos  Configure center address 
spring.cloud.nacos.config.server-addr=localhost:8848
#  The type of configuration file 
spring.cloud.nacos.config.file-extension=yaml

（4） stay nacos Create a new console DataID by cloud-producer-server-dev.yaml Configuration set of ：

Why? DataID The named cloud-producer-server-dev.yaml We'll talk about

 （5） Writing test classes ：

// After configuration Publishing , Dynamic refresh configuration 
@RefreshScope
@RestController
@RequestMapping("provider")
public class ProviderController
{
    //  Use native annotations @Value() Import configuration 
    @Value("${user.id}")
    private String id;
    @Value("${user.name}")
    private String name;
    @Value("${user.age}")
    private String age;

    @GetMapping("getNacosConfig")
    public String providerTest()
    {
        return " I am a provider, Successfully obtained nacos Configure the data of the center ：(id:" + id + ",name:" + name + ",age:" + age +")";
    }
}

（6） Start service validation ：

         Start project , visit http://localhost:8080/provider/getNacosConfig Interface , You can see nacos The configuration information of the configuration center has been effective and successfully obtained

（7） Verify the dynamic refresh configuration ：

         Dynamic refresh of configuration is one of the core functions of the configuration center , Suppose I need to modify it now user.name Value , Then I'll just change Nacos Will the configuration in take effect ？ Let's try to directly Nacos Change the configuration in to “zhangsan”, Here's the picture ：

  At this time, do not restart the project and re access the interface , give the result as follows ：

         We found that the configuration has been refreshed dynamically , Why is that ？ In fact, it's because we added @RefreshScope The effect of annotation .

// After configuration Publishing , Dynamic refresh configuration 
@RefreshScope
@RestController
@RequestMapping("provider")
public class ProviderController

2、Nacos Core concept of ：

2.1、Data ID：

（1）Data ID Naming format for ：

         Previously we demonstrated in nacos Create a new console DataID by cloud-producer-server-dev.yaml Data set of , So this Data ID What is it? ？Data ID Is the unique identification of the configuration set , An application can contain multiple configuration sets , Each configuration set needs to be identified by a meaningful name . that Data ID How to get the value ？ The popular format is “ Prefix - Environmental Science - Extension ”, As shown below ：

${spring.cloud.nacos.config.prefix}-${spring.profiles.active}.${spring.cloud.nacos.config.file-extension}

① prefix： Prefix , The default is spring.application.name Value , You can also configure items through spring.cloud.nacos.config.prefix To configure the .

#  If not specified , The default scheme is the application name 
spring.application.name=cloud-producer-server

#  Manually specify the configuration dataID Prefix identification 
# spring.cloud.nacos.config.prefix=cloud-producer-server-config

② active： Configure the operating environment , That is, the current environment corresponds to profile.

Be careful ： When spring.profiles.active It's empty time , Corresponding connector ”-“ There will be no ,dataId The splicing format of becomes ${prefix}.${file-extension}

# dev Represents the development environment 
spring.profiles.active=dev

③ file-exetension： The type of configuration file , The default is properties, You can also configure items through spring.cloud.nacos.config.file-extension To configure the , At present, the supported types are TEXT、JSON、XML、YAML、HTML、Properties

#  Specify the configuration file type as yaml file 
spring.cloud.nacos.config.file-extension=yaml

④ Final configuration ：

         Go through the first three steps , We ended up with nacos The new configuration file on the console of the configuration center is ：cloud-producer-server.yaml

2.2、 Environmental isolation - Namespace Namespace：

        Nacos Introduce namespace Namespace To manage and isolate multiple environment configurations and services . for example , You may have a local development environment dev、 Test environment test、 Production environment prod Three different environments , Then you can create three different Namespace Distinguish between different environments . Create it as follows ：

  After creation , You can go to Nacos You can see different namespaces on the configuration list of the console , Here's the picture ：

         After successfully creating the new namespace , You can go to springboot Configuration file configuration namespace id Switch to the corresponding namespace , And get the configuration file under the corresponding space , But without specifying the namespace configuration , The default configuration is public In the space , The way to specify the namespace is as follows ：

#  Corresponding to the created namespace ID, Here it corresponds to dev Namespace 
cloud.nacos.config.namespace=483bb765-a42d-4112-90bc-50b8dff768b3

2.3、 Business isolation -Group grouping ：

        Group It can also realize the function of environmental isolation , but Group The main purpose of the design is to group different services in the same environment , Divide the configuration files of different microservices into the same group ,Nacos If you don't specify Group, The default grouping is DEFAULT_GROUP.

         without Group, Just imagine this scene ： There are two microservices , One is the order system , One is the user system , But they have the same configuration , such as datasource-url, So how to distinguish ？ Now Group That comes in handy . The order system in the above scenario 、 The user system can be divided into a separate group , such as ORDER_GROUP、USER_GROUP, Of course, this is a fine-grained grouping , According to the business of the enterprise, multiple micro services can also be divided into a group .

         Next, we will demonstrate how to specify grouping when creating configuration sets and when integrating , Or the previous example , The new configuration set is specified in the following location Group grouping ：

  The next in application.properties File grouping ：

spring.cloud.nacos.config.namespace=483bb765-a42d-4112-90bc-50b8dff768b3

3、 Summary ：

Nacos Implementing configuration management and dynamic configuration refresh is very simple , Summarize the following steps ：

• ① Add corresponding spring-cloud-starter-alibaba-nacos-config rely on
• ② Use native annotations @Value() Import configuration
• ③ Use native annotations @RefreshScope Refresh configuration
• ④ Do a lot of environment configuration isolation according to your business scenario (Namespace)、 Different business configurations are isolated (Group)

4、 Shared configuration ：

         When we have more and more micro Services , There must be the same configuration , At this time, we can extract the same configuration as the common configuration of the project , For example, the data source information in the cluster 、 Log configuration information ,nacos It also supports the writing of multiple configuration sets in one configuration center .

（1） We are nacos New two in Data ID Namely db.yaml and log.yaml The file of .

（2） Add some configuration contents to the configuration file respectively

（3） stay Springboot Add the following nacos To configure ：

spring:
  cloud:
    nacos:
      config:
        extension-configs[0]:
          data-id: db.yaml
          #  The default is DEFAULT_GROUP
          group: DEFAULT_GROUP
          #  Whether to refresh dynamically , The default is false
          refresh: true
        extension-configs[1]:
          data-id: log.yaml
          group: DEFAULT_GROUP
          refresh: true

In order to more clearly configure shared Data Id, Official recommendation shared-configs, The configuration is as follows ：

spring:
  cloud:
    nacos:
      config:
        shared-configs[0]:
          data-id: db.yaml
          #  The default is DEFAULT_GROUP
          group: DEFAULT_GROUP   
          #  Whether to refresh dynamically , The default is false
          refresh: true   
        shared-configs[1]:
          data-id: log.yaml
          group: DEFAULT_GROUP
          refresh: true

（4） reflection ： Here 2 The same configuration appears in files ,nacos How to choose ？

         When more than one Data Id When the same configuration appears at the same time , Its priority relationship is spring.cloud.nacos.config.extension-configs[n].data-id among n The greater the value of , The higher the priority .

Be careful ：spring.cloud.nacos.config.extension-configs[n].data-id The value of must have a file extension , The file extension can support properties, You can support yaml/yml. here spring.cloud.nacos.config.file-extension The configuration of the user-defined extension configuration Data Id File extensions have no effect .

（5） Configure load priority in different ways ：

        Nacos The configuration center currently provides the following three configuration capabilities from Nacos Pull the relevant configuration , When the three methods are used together , One of their priorities is :A < B < C：

• A： adopt spring.cloud.nacos.config.shared-configs[n].data-id Support multiple shares Data Id Configuration of
• B： adopt spring.cloud.nacos.config.extension-configs[n].data-id The way to support multiple extensions Data Id Configuration of
• C： Through internal rules (spring.cloud.nacos.config.prefix、spring.cloud.nacos.config.file-extension、spring.cloud.nacos.config.group) Automatically generate related Data Id To configure

Reference article ：

SpringBoot2.X Integrate Nacos Do configuration center

Fifty five pictures show you the soul ferry of micro service Nacos How strong ？