Table of contents
Distributed configuration center_Nacos configuration dynamic refresh
Distributed configuration center_Dubbo service docking distributed configuration center
Distributed configuration center_Nacos cluster architecture introduction
Data Persistence of Distributed Configuration Center_Nacos
Distributed configuration center_Nacos cluster configuration
Distributed Traffic Protection_Understanding Distributed Traffic Protection
Distributed Traffic Protection_Know Sentinel
Distributed configuration center_Nacos configuration dynamic refresh
Configure Dynamic Refresh
The dynamic refresh of the configuration only needs to be annotated with @RefreshScope.
Annotation method
@RestController
/* 只需要在需要动态读取配置的类上添加此注解就可以 */
@RefreshScope
public class ConfigController {
@Value( "${config.config}" )
private String appName;
@GetMapping("/getConfig")
public String nacosConfingTest2(){
return(appName);
}
}Real-time effect feedback
1. Nacos distributed configuration center realizes dynamic refresh through ____ annotation.
A Refresh
B RefreshScope
C Scope
D above are all wrong
Distributed configuration center_Dubbo service docking distributed configuration center
POM introduces dependencies
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-bootstrap</artifactId>
</dependency>
Console creates dataId
Create bootstrap.yml
spring:
main:
allow-bean-definition-overriding: true
allow-circular-references: true
application:
#应用名字
name: consumer-dubbo-order
cloud:
nacos:
config:
# 设置应用名字
prefix: ${spring.application.name}
# 配置文件后缀
file-extension: yaml
# 配置中心地址
server-addr: 192.168.66.101:8848
profiles:
# 设置环境
active: devtest
Request http://localhost:80/order/index
Distributed configuration center_Nacos cluster architecture introduction
Why do you need to build a Nacos cluster
By default, Nacos uses the embedded database Derby to store data. Therefore, if you start multiple Nacos nodes under the default configuration, there will be consistency problems in data storage. In order to solve this problem, Nacos adopts a centralized storage method to support cluster deployment, and currently only supports MySQL storage.
Nacos supports three deployment modes
1. Stand-alone mode - for testing and stand-alone trial.
2. Cluster mode - used in production environments to ensure high availability.
3. Multi-cluster mode - for multi-data center scenarios.
cluster mode
Real-time effect feedback
1. Build a Nacos cluster to solve the _____ problem.
A data is inconsistent
B safe
C single point of failure
D above are all wrong
2. The default memory database of Nacos is____.
A SQLite
B MySQL
C Derby
D above are all wrong
Data Persistence of Distributed Configuration Center_Nacos
Initialize the database
The Nacos database script file enters the \nacos\conf directory in the compressed package when we download Nacos-server, the initialization file: nacos-mysql.sql Here I create a database named mynacos , and then execute the initialization script. After success, 11 tables will be generated;
Modify the configuration file
Here is the need to modify the configuration file of Nacos-server. Nacos-server is actually a Java project or a Springboot project. Its configuration file is in the nacos\conf directory, named application.properties , and the data source configuration is added at the bottom of the file:
spring.datasource.platform=mysql
db.num=1
db.url.0=jdbc:mysql://127.0.0.1:3306/mynacos?
characterEncoding=utf8&connectTimeout=1000&so
cketTimeout=3000&autoReconnect=true
db.user=root
db.password=123456
Start Nacos-server and Nacos-config
Start the Nacos-server first, and enter the Nacos console after the startup is successful. At this time, the Nacos console has a new look, and the previous data is gone.
Note: Because of the addition of a new data source, Nacos reads all configuration files from mysql, and the database we just initialized is clean, so naturally there will be no data and information to display.
Create a new configuration file DataID: nacos-config.yml in the public space (public), the configuration content is as follows:
server:
port: 9989
nacos:
config: 配置文件已持久化到数据库中...Then start the demo project in Nacos (4). After the service starts successfully, observe the Nacos console as follows
Verify whether it is persisted to the database
Distributed configuration center_Nacos cluster configuration
cluster start
Simulate 3 machines locally through 3 ports, the ports are: 8848, 8858, 8868.
#copy3份解压后的nacos，修改各自的application.properties中的端口号，分别为：8848，8858，8868
server.port=8848
server.port=8858
server.port=8868
The cluster.conf file is placed in the respective conf directory, and the content of the file is:
192.168.66.100:8848
192.168.66.100:8858
192.168.66.100:8868Start the Nacos service
./startup.sh
Use Nginx as load balancing to access Nacos of the cluster
Environment installation
yum -y install gcc make automake pcre-devel
zlib zlib-devel openssl openssl-devel
Install Nginx
./configure
make && make installConfigure nginx.conf file
#定义upstream名字，下面会引用
upstream nacos{
#指定后端服务器地址
server 192.168.66.100:8848;
server 192.168.66.100:8858;
server 192.168.66.100:8868;
}
server {
listen 80;
server_name localhost;
location / {
proxy_pass http://nacos; #引用upstream
}
}
Restart Nginx
docker restart nginx
The load balancing of nacos access can be achieved by accessing nginx
request http://localhost/nacos
Distributed Traffic Protection_Understanding Distributed Traffic Protection
In a distributed system, mutual calls between services generate distributed traffic. How to protect traffic through components and effectively control traffic is one of the technical challenges of distributed systems.
What is Service Avalanche
Suppose I have a microservice system, which contains four microservices of ABCD, all of which are built in cluster mode.
Avalanche problem:
Microservices call each other, because a service failure in the call chain causes the entire link to be inaccessible.
solution
Service Protection Technology
Multiple service protection technologies are supported in Spring Cloud:
1、Hystrix
2、Sentinel
3、Resilience4J
Sentinel Service Fault Tolerance Ideas
Sentinel is a service fault-tolerant component of Spring Cloud Alibaba, and we often call it "anti-traffic sentinel". It is the patron saint of the core scenarios of Alibaba’s Double Eleven promotion, and has built-in rich service fault-tolerant application scenarios. It takes traffic as the entry point and achieves the purpose of maintaining service stability through various internal and external prevention and control methods.
Internal Exception Governance
In Sentinel, we can handle internal exceptions by downgrading and fusing. The so-called downgrade means that when the service call has a response timeout, service exception, etc., we can execute a piece of "downgrade logic" inside the service.
The so-called circuit breaker means that when the amount of abnormal calls reaches a certain judgment condition, for example, when the ratio of abnormal downgrade and slow call requests reaches a threshold and the number of downgrade requests reaches a certain number within the window time, the microservice stops calling the target service for a period of time, and all incoming requests directly execute the downgrade logic. Therefore, the circuit breaker is the cumulative result of "multiple service call exceptions".
external flow control
Traffic limiting is a kind of traffic shaping and flow control scheme. In Sentinel, we can set a flow-limiting rule for each service according to the processing capacity of the cluster, and control external access traffic from the dimension of QPS or the number of concurrent threads. Once the number of visits exceeds the threshold, subsequent requests will be "fast fail", which is the most commonly used traffic limiting method.
Real-time effect feedback
1. The following ___ can solve the service avalanche problem.
A timeout mechanism
B fuse mechanism
C flow control
All of the above are correct
2. Sentinel external flow control refers to _____.
A fuse
B downgraded
C current limit
D isolated
Distributed Traffic Protection_Know Sentinel
Sentinel is an open source project of Ali, which provides multiple dimensions such as flow control, circuit breaker degradation, and system load protection to ensure the stability of services.
Key Features of Sentinel
Sentinel is divided into two parts
1. Console (Dashboard): The console is mainly responsible for managing push rules, monitoring, cluster current limit allocation management, machine discovery, etc.
2. Core library (Java client): does not depend on any framework/library, can run in the runtime environment of Java 7 and above, and also has good support for Dubbo / Spring Cloud and other frameworks.
Notice:
Sentinel can be simply divided into Sentinel core library and Dashboard. The core library does not depend on Dashboard, but it can achieve the best results in combination with Dashboard.
Who is using Sentinel?
Comparison of Sentinel with Hystrix and resilience4j
Real-time effect feedback
1. The following advantages of Sentinel are ___.
A provides out-of-the-box console
B Rich circuit breaker downgrade strategy
C supports traffic shaping
All of the above are correct