[Spring Cloud] Detailed explanation of Nacos configuration management

1 Introduction

1.1 Why configuration management is needed

In the complex software development and deployment process, configuration management plays a vital role. The following are the main benefits provided by configuration management:

Decoupling configuration from code : By separating configuration from code, you can modify the behavior of your application without changing the code. This is especially important for multi-environment deployments (e.g. development, test, production, etc.), each of which may require different configurations.
Dynamic configuration : The configuration can be modified dynamically while the application is running, and the application can respond to these changes immediately without redeploying or restarting.
Centralized management : For large-scale microservice architecture, configuration management tools provide a centralized storage to facilitate unified management and monitoring of the configuration of all services.
Version control and rollback : Configuration management tools often include version control functions so that erroneous configuration changes can be quickly identified and rolled back.

To understand more intuitively, consider a simple example: a configuration item for a database connection.

database:
  host: 127.0.0.1
  port: 3306
  user: admin
  password: secret

When the address of the database server changes, without configuration management, you may need to manually update the code or rebuild the application. But with configuration management, you only need to modify it in the centralized configuration center, and all services using that configuration will automatically adapt.

1.2 Nacos configuration management overview

Nacos (Dynamic Naming and Configuration Service) is a dynamic naming and configuration service that provides centralized configuration management, service registration and discovery functions for microservice architecture. In terms of configuration management, Nacos provides the following features:

Centralized configuration management : allows the configuration of all microservices to be managed in a central location.
Dynamic push : When configuration changes, Nacos can push to related services in real time.
Version and history : Nacos provides version control for configuration changes and supports historical version query and rollback.
Grayscale publishing : Ability to publish new configurations to specific service instances or groups without affecting other instances.
Access Control : Control access to configurations through namespaces, roles, and permissions.

Simply, Nacos' configuration management can be viewed as a highly available "key-value" storage system. Among them, "key" usually consists of Data IDand Group, and "value" is the specific configuration content.

The following is a simple Java code example using Nacos to obtain configuration:

Properties properties = new Properties();
properties.put("serverAddr", "127.0.0.1:8848");
properties.put("namespace", "YOUR_NAMESPACE");
ConfigService configService = NacosFactory.createConfigService(properties);
String config = configService.getConfig("YOUR_DATA_ID", "YOUR_GROUP", 3000);
System.out.println(config);

Through this example, we can see how to integrate Nacos in Java applications to obtain dynamic configuration. As the configuration changes, the application can receive the new configuration and adjust accordingly.

In general, Nacos's configuration management function provides an efficient, flexible, and reliable way for microservices to manage and use configurations, ensuring stable operation and rapid iteration of services.

2. Core concepts of Nacos configuration management

2.1 Data ID and Group

In Nacos configuration management, each configuration has a unique identifier, which consists of Data IDand Group.

Data ID : It is a unique identifier for each configuration item and usually reflects the content or purpose of the configuration. For example, database-configit can be a configuration about database connection information.
Group : To better organize and manage configurations, Nacos provides Groupthe concept of. Through Group, you can group related configuration items together. For example, DEV, TESTand PRODmay be three groups in different environments, used to distinguish the configuration of development, test and production environments.

Combinations Data IDand Groupcan locate a specific configuration, such as the configuration database-configunder DEVthe group.

Example :

Consider a scenario where you have an application deployed in three environments: development, testing, and production. You can use the following configuration flags:

Data ID: app-config
Group: DEV, TEST, PROD

At this point, app-config@DEVpoint to the configuration of the development environment, and app-config@PRODpoint to the configuration of the production environment.

2.2 Configuration version and history

Nacos provides version control for every configuration change. Whenever you change the configuration content, Nacos will generate a new version number for it. This makes it possible to track configuration changes and roll back to a specific version.

Version tracking : You can view all historical versions of configuration items and find out the changes and time of each version.
Configuration rollback : If you find a problem with the latest configuration, you can easily roll back to a previous version.

Example :

Suppose you modify the value of a configuration item. In the Nacos console, you can view the version history of this configuration item, find the changes you made, and view its corresponding version number. If necessary, you can select an earlier version and perform a rollback operation.

2.3 Configure monitoring

Configuration monitoring is a powerful feature in Nacos configuration management. An application or service can monitor the configuration items it depends on. Once these configuration items change, Nacos will notify these listeners, and the application or service can then adjust its behavior based on the new configuration.

This mechanism allows applications to respond to configuration changes in real time without restarting or redeploying.

Example :

Consider a microservice that relies on a certain database connection configuration. When the database is migrated to a new server, you only need to update the relevant configuration in Nacos. After the microservice listens to this change, it can automatically disconnect the current database connection and reconnect to the new database server without any manual intervention.

Using the Nacos client for Java, you can set up a listener like this:

String dataId = "database-config";
String group = "DEV";
long timeoutMs = 3000;
ConfigService configService = NacosFactory.createConfigService("127.0.0.1:8848");
String content = configService.getConfig(dataId, group, timeoutMs);
configService.addListener(dataId, group, new Listener() {
    
    
    @Override
    public void receiveConfigInfo(String configInfo) {
    
    
        // 当配置变更时, 这里的代码将被执行
        System.out.println("配置已变更：" + configInfo);
    }

    @Override
    public Executor getExecutor() {
    
    
        return null;
    }
});

This code first gets the configuration from Nacos and then sets a listener for this configuration. When database-config@DEVthe content of the changes, receiveConfigInfothe method will be called, where you can perform the required logic, such as re-establishing the database connection.

3. Nacos configuration management process

3.1 Creation and deletion of configurations

Creating a configuration : In Nacos, creating a configuration is a simple process. You need to select or create a specific one Group, then provide one for the configuration Data IDand fill in the configuration content.

Example :

Using the Nacos console:

Log in to the Nacos console.
Select "Configuration Management" > "Configuration List" from the left menu.
Click the "Create Configuration" button.
Fill in Data IDand Groupconfigure the content, and then save.

Nacos client using Java:

String dataId = "new-config";
String group = "DEFAULT_GROUP";
String content = "This is a new configuration.";
ConfigService configService = NacosFactory.createConfigService("127.0.0.1:8848");
boolean result = configService.publishConfig(dataId, group, content);
System.out.println("配置创建: " + (result ? "成功" : "失败"));

Deleting a configuration : When a configuration is no longer needed, you can delete it from Nacos. Please note that once deleted, you cannot restore the configuration.

Example :

Using the Nacos console:

Find the configuration you want to delete in the configuration list.
Click the "Delete" button to the right of the configuration.
Click "OK" in the pop-up confirmation box.

Nacos client using Java:

String dataId = "new-config";
String group = "DEFAULT_GROUP";
ConfigService configService = NacosFactory.createConfigService("127.0.0.1:8848");
boolean result = configService.removeConfig(dataId, group);
System.out.println("配置删除: " + (result ? "成功" : "失败"));

3.2 Modification and acquisition of configuration

Modify the configuration : As the application or environment changes, you may need to update the configuration in Nacos.

Example :

Using the Nacos console:

Find the configuration you want to modify in the configuration list.
Click the "Edit" button to the right of the configuration.
Modify the configuration content and click "Save".

Nacos client using Java:

String dataId = "new-config";
String group = "DEFAULT_GROUP";
String newContent = "This is the updated configuration content.";
ConfigService configService = NacosFactory.createConfigService("127.0.0.1:8848");
boolean result = configService.publishConfig(dataId, group, newContent);
System.out.println("配置更新: " + (result ? "成功" : "失败"));

Obtain configuration : When the application starts or runs, it needs to obtain the configuration of its dependencies from Nacos.

Example :

Nacos client using Java:

String dataId = "new-config";
String group = "DEFAULT_GROUP";
long timeoutMs = 3000;
ConfigService configService = NacosFactory.createConfigService("127.0.0.1:8848");
String content = configService.getConfig(dataId, group, timeoutMs);
System.out.println("获取到的配置内容: " + content);

3.3 Configuration synchronization and distribution

In a distributed system, it is crucial to ensure that the configuration is synchronized across all nodes. Nacos provides mechanisms for this.

Configuration synchronization : When you modify the configuration in the Nacos console, Nacos will automatically synchronize these changes to all clients listening to the configuration.

Distribution of configuration : In multi-data center or cross-region deployment, Nacos supports distributed management of configuration. You can create and manage configurations in the main data center and then distribute these configurations to other data centers or regions.

Example :

Consider a deployment spanning two data centers. You can create and modify configurations in the Nacos instance in the primary data center, and then the configuration is automatically distributed to the Nacos instances in the secondary data center through the synchronization mechanism of the Nacos cluster. No matter which data center the client is connected to Nacos, it can obtain the latest configuration content.

In order to implement this function, you need to specify the data synchronization strategy and the address of the target data center in the Nacos cluster configuration.

4. Practical Guidelines

4.1 Environment and tool preparation

Before starting the practice, we need to ensure that we have the appropriate environment and tools.

Environmental requirements :

Operating system : It is recommended to use a Linux-based operating system, such as CentOS, Ubuntu, etc.
JVM : Since Nacos server is developed based on Java, JDK 1.8 or higher is required.
Network : Make sure all machines (Nacos servers, application servers, etc.) are on the same network or subnet and can reach each other.

Tool preparation :

Nacos Server : You can download the latest version from the Nacos official website.
Maven : Dependency management for Java projects.
IDE : such as IntelliJ IDEA or Eclipse, used for development and testing.

4.2 Example: Using Nacos to manage application configurations

This example will guide you on how to use Nacos for configuration management for a simple Java application.

Create application :

Create a simple application based on Spring Boot. pom.xmlAdd Nacos dependencies in :

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
    <version>LATEST_VERSION</version>
</dependency>

Configure Nacos :

In src/main/resourcesthe directory, create or modify bootstrap.propertiesthe file and add the following content:
```
spring.cloud.nacos.config.server-addr=YOUR_NACOS_SERVER_ADDRESS
spring.application.name=myapp
```
Release configuration :

In the Nacos console, myappcreate a configuration for . For example, settings message=Hello Nacos!.

Use the configuration in your application :

In a Spring Boot application, you can use @Valueannotations to obtain configuration values:

@RestController
public class ConfigController {
      
      

    @Value("${message}")
    private String message;

    @GetMapping("/message")
    public String getMessage() {
      
      
        return message;
    }
}

Run the application :

Start the Spring Boot application and access /messagethe path. You should see output like "Hello Nacos!"

4.3 Dynamically refresh configuration

A powerful feature of Nacos is the ability to dynamically refresh configurations. This means that when the configuration changes in Nacos, your application will automatically get the latest configuration values without restarting.

Enable dynamic refresh :

In bootstrap.propertiesthe file, add the following configuration items:
```
spring.cloud.nacos.config.refresh-enabled=true
```

Use@RefreshScope :

On the Bean you want to dynamically refresh, add @RefreshScopeannotations.

@RestController
@RefreshScope
public class ConfigController {
      
       /* ... */ }

Test dynamic refresh :

In the Nacos console, change messagethe value of , for example to "Hello Nacos v2!". In the application, access /messagethe path again and you should see new message content indicating that the configuration has been successfully refreshed.

The above steps show you how to use Nacos for configuration management in a real application and take advantage of its dynamic refresh feature. This ensures that configuration changes are reflected in the application in real time, enhancing application flexibility and responsiveness.

5. Advanced features

5.1 Configured persistent storage

Persistent storage is key to ensuring the security and reliability of configuration data. In Nacos, the configured persistent storage has the following characteristics:

Storage mechanism : Nacos uses an embedded database (such as Derby) by default for configured persistent storage, but in a production environment, it is recommended to use an external database (such as MySQL) to ensure data stability and security.
Data backup and recovery : It is a good practice to regularly back up configuration data to an external storage device or cloud storage. Nacos provides convenient tools and interfaces to allow users to easily back up and restore configuration data.
```
# 示例：使用 Nacos 提供的备份工具
$ nacos-config-backup.sh -o backup.tar.gz
```
Scalability : Nacos's storage layer is pluggable, which means you can easily replace it with a custom storage solution, such as connecting to a distributed file system or other database system.

5.2 Grayscale release and configuration rollback

Grayscale release is a strategy for deploying new features in production that allows developers to release changes gradually, thereby reducing the risk caused by new changes. Nacos supports grayscale release configuration:

Tag management : In Nacos, you can add tags to the configuration, such as beta, productionetc., to identify which environments or user groups it applies to.
Publishing strategies : Based on tags, Nacos allows you to develop publishing strategies. For example, release a new configuration to tagged instances first beta, observe how it performs, and then decide whether to release it to the wider user base.
Configuration rollback : If a new configuration causes problems, Nacos provides a configuration rollback feature that allows you to quickly revert to a previous configuration version.
```
# 示例：使用 Nacos 控制台回滚到某一配置版本
$ nacos-config-rollback.sh -v VERSION_NUMBER
```

5.3 Access control and rights management

In order to ensure the security of configuration, Nacos provides complete access control and permission management functions:

Users and roles : In Nacos, users and roles can be defined, and different permissions can be assigned to each role, such as reading configuration, modifying configuration, etc.
Configuration-level access control : You can set access permissions for specific configuration items or configuration groups to ensure that only authorized users or services have access.
Access log : Nacos records all access requests, including who, when, and what was accessed. Not only can this help track potential security issues, but it can also be used for auditing and compliance with regulatory requirements.
Integrate external authentication systems : If your organization already has existing authentication and authorization systems (such as LDAP or OAuth), Nacos provides corresponding plug-ins or interfaces that allow you to easily integrate these systems.

Through the above-mentioned advanced features, Nacos can provide stable, secure and efficient configuration management services in complex production environments.

6. Frequently Asked Questions and Solutions

6.1 Resolution of configuration item conflicts

In an environment where multiple people or teams work together, configuration item conflicts are a common problem. Conflicts can occur when two or more changes are made to the same configuration item at the same time.

Version control : Nacos provides a configuration version history function, allowing you to view the modification history of configuration items and find out when and who introduced conflicts.
Merge conflicts : Once configuration conflicts are detected, they need to be merged in time. This usually requires communication with the teams or individuals involved and merging the conflict when consensus is reached.
```
# 示例：查看配置项的版本历史
$ nacos-config-history.sh -id CONFIG_ID
```
Best practices for avoiding conflicts : It is recommended to break down configurations into smaller, functionally related units to reduce the possibility of multiple teams or individuals modifying the same configuration at the same time.

6.2 Troubleshooting configuration push delay

Real-time configuration is critical for many applications. If you notice delays in configuration push, here are some troubleshooting steps:

Check the network status : Make sure the network connection between the Nacos server and the application is smooth and stable.
Check Nacos server load : excessive server load may cause processing delays. Consider expanding the Nacos cluster or optimizing the configuration to reduce server pressure.
Application log troubleshooting : Check the application logs to see if there are errors or exceptions related to configuration updates.
```
# 示例：查看Nacos服务器的状态
$ nacos-server-status.sh
```
Make sure you use configuration listeners : Your application should set up listeners correctly to receive timely updates when configuration changes.

6.3 Enhancement of configuration storage security

Configuration information may contain sensitive data, such as database connection strings, API keys, etc. Protecting the security of this information is critical.

Encrypted configuration : Sensitive configuration items can be stored in an encrypted manner, and the application will decrypt them when reading the configuration. Nacos provides plug-in support, allowing you to integrate external encryption tools.
Access control : Ensure that only authorized users and services have access to sensitive configurations. Use Nacos's access control function to set different access permissions for different configurations.
Regular auditing : Regularly check and audit configuration access logs to ensure there is no unauthorized access.

Through the above strategies, you can effectively improve the security of the configuration and protect sensitive information from being leaked.

7. Conclusion

7.1 Summary of this article

In modern microservice architecture, configuration management has become a core component to ensure system flexibility and agility. Nacos, as a solution that integrates service registration, discovery, and configuration management, provides us with an efficient, stable, and easy-to-use platform to implement these functions.

This article explores the configuration management function of Nacos in depth, starting from the basic concepts and introducing in detail all aspects of configuration management, such as core concepts, configuration management processes, practice guides, and advanced features. We also provide solutions to some common problems you may encounter in configuration management, hoping to provide you with a reference when using Nacos.

7.2 Recommended reading and further learning resources

Nacos Official Documentation : This is the best starting point for learning Nacos, describing all its features and configuration options in detail. Click here to visit
Nacos GitHub : If you want to have a deeper understanding of the internal implementation of Nacos or participate in open source projects, you can visit its GitHub repository. Click here to visit
Microservice Architecture Design : This book provides an in-depth exploration of the design principles, patterns, and practices of microservice architecture. It is a very good resource to help you better understand the relationship between microservices and configuration management.
Spring Cloud Alibaba : This is a Spring Cloud project that integrates Alibaba Cloud microservice solutions such as Nacos, Sentinel, and Seata. It is suitable for developers who want to use Nacos in Spring projects. Click here to visit

I hope these resources will help you in your in-depth research in the field of microservices and configuration management.