Alibaba cloud microservices (II) distributed service configuration center and Nacos usage scenarios and implementation introduction

If the registry is used for addressing in microservices , Help one service call another service , The function of service configuration is to modify the configuration of each service more conveniently , for instance , If we use a configuration file to configure information , If you want to modify a configuration item , We need to repackage , Release , But if you use the configuration center , Then you only need to modify

About using the configuration center for Shenma , I think there are mainly the following reasons ：
1. Separate multi-environment configuration
2. More flexible management permissions
3. Higher security

About 1. Separate multi-environment configuration
In the same case, different configuration environments may be required
as follows , We are in the configuration center nacos Add a configuration information


Test in the service to see whether the configuration information can be read

You can see from the figure below that the configuration information is read successfully

The configuration information just now is in properties Configured in , If you change the configuration file to yaml What will be done ？


You can see the read yaml File information
After that, you can start from Nacos Two configuration files were observed in time , It is more convenient to manage files

For configuration information, it is common that the same code may be in different scenarios profile and namespace There are different configurations on
profile It's in different profile You can have the same configuration item but different values
As follows, in the environment profile Change to develop

Use the app name +profile To create

About namespace Different
Create a new one namespace training

Record his namespace id

Add to configuration

You can see the read namespace Configuration information of succeeded
About Nacos
Nacos There are mainly service registration and discovery , Health check and access policy

The picture below is nacos and zookeeper as well as Eureka Comparison of

You can see Nacos You can freely choose a consistency agreement , How to choose a consistency protocol , It can be understood as
If the success or failure of a single write request is important , Should guarantee cp The consistency of , because cp The consistency of services sacrifices the overall availability of services in exchange for data consistency
If the success or failure of a single request is not very important , Instead, data consistency can be maintained through subsequent data compensation mechanisms , Should guarantee ap The consistency of
besides ,Nacos It also has its own advantages in access strategy
The access strategy of the server is more flexible , Because there is no need to modify the client and it can be adjusted more flexibly in the process of use

In the data service model , Services and clusters can store different service configurations for service management , Like some specific information, such as ip And ports can be managed by the instance
Nacos The implementation of is mainly divided into the following modules

Preliminary permission verification is defined in the user interface module , Parameter verification and data conversion
The push module manages all subscribers , And push trigger , Aggregation and weight removal
The health check module supports server-side detection and client-side reporting
Access policies filter the server through different access policies , Currently, the supported access policies are tag based access policies

Store data and server Synchronization between to ensure data consistency