Learn SpringCloud Eureka to take you from zero to one

What is a Service registry

A service registry is a core component for service registration and management. Similar to a directory service, it is mainly used to store service information, such as service provider URL string and routing information. A service registry is one of the most fundamental infrastructures in an SOA architecture.

1. The role of the service registry

1. Registration of services

2 Service discovery

2. Common registry

1 Dubo registry Zookeeper

2 SpringCloud的Eureka

3. What problems do service registries solve

1. Service management

2. Service dependency management

4. What is the Eureka Registry

Eureka is a Service discovery component developed by Netflix. It is itself a REST-based service, and SpringCloud integrates it into its sub-project to realize SpringCloud’s service registration and discovery, as well as provide load balancing and registration

4.1 Three roles in the Eureka Registry

Eureka Server

Registers and discovers services through interfaces such as Register, Get, and Renew.
Application Service (Service Provider)

Service Provider

Register your service instance with Eureka Server
Application Client (Service Consumer)

Service caller

Obtain the service list from Eureka Server and consume the service

2. Introduction to Eureka

1. Create projects

1.1 Adding a Dependency

<?xml version="1.0" encoding="UTF-8"? >
<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.13. RELEASE</version>
		<relativePath /> <! -- lookup parent from repository -->
	</parent>
	<groupId>com.luyi</groupId>
	<artifactId>springcloud-eureka-server</artifactId>
	<version>0.0.1 - the SNAPSHOT</version>
	<name>springcloud-eureka-server</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springframework.cloud</groupId>
				<artifactId>spring-cloud-dependencies</artifactId>
				<version>Dalston.SR5</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-config</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-eureka-server</artifactId>
		</dependency>
	</dependencies>
	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>
</project>
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1.2 Modifying the Startup Class

@EnableEurekaServer
@SpringBootApplication
public class EurekaApplication {
    public static void main(String[] args) { SpringApplication.run(EurekaApplication.class, args); }}Copy the code

1.3 Modifying the Global Configuration File

Server. port=8761 # do you want to register with eureka-server? Defaults to true eureka. Client. RegisterWithEureka = false # whether from eureka - service information in the server, the default is true eureka. Client. FetchRegistry = falseCopy the code

1.4 Accessing the Eureka-Server Service Management Platform using a Browser

3. Build Eureka cluster

1. Create projects

1.1 Creating a Project

springcloud-eureka-server-ha

1.2 Modifying the Configuration File

When setting up a Eureka cluster, multiple configuration files need to be added, and the multi-environment configuration method of SpringBoot is used to add as many configuration files as needed in the cluster

1.3 Configuring cluster Nodes in the Configuration file

Eureka1

Port =8761 # set eureka instance name, Eureka.instance. hostname=eureka1 Point to another registry eureka. Client. ServiceUrl. DefaultZone = http://eureka2:8761/eureka/Copy the code

Eureka2

Port =8761 # set eureka instance name, Eureka.instance. hostname=eureka2 Point to another registry eureka. Client. ServiceUrl. DefaultZone = http://eureka1:8761/eureka/Copy the code

1.4 Adding the LogBack Log Configuration File

<?xml version="1.0" encoding="UTF-8" ? >
 <configuration>
<! Do not use relative path in LogBack configuration -->  
    <property name="LOG_HOME" value="${catalina.base}/logs/" />  
    <! -- Console output -->   
    <appender name="Stdout" class="ch.qos.logback.core.ConsoleAppender">
       <! -- Log output code -->  
        <layout class="ch.qos.logback.classic.PatternLayout">   
             <! Format output: %d indicates the date, %thread indicates the thread name, %-5level indicates the level of 5 characters from the left. % MSG indicates the log message, %n indicates the newline character. 
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n   
            </pattern>   
        </layout>   
    </appender>   
    <! Generate log files per day -->   
    <appender name="RollingFile"  class="ch.qos.logback.core.rolling.RollingFileAppender">   
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <! -- Log file output file name -->
            <FileNamePattern>${LOG_HOME}/server.%d{yyyy-MM-dd}.log</FileNamePattern>   
            <MaxHistory>30</MaxHistory>
        </rollingPolicy>   
        <layout class="ch.qos.logback.classic.PatternLayout">  
            <! Format output: %d indicates the date, %thread indicates the thread name, %-5level indicates the level of 5 characters from the left. % MSG indicates the log message, %n indicates the newline character. 
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n   
            </pattern>   
       </layout> 
        <! -- Maximum size of log file -->
       <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
         <MaxFileSize>10MB</MaxFileSize>
       </triggeringPolicy>
    </appender>     

    <! -- Log output level -->
    <root level="DEBUG">   
        <appender-ref ref="Stdout" />   
        <appender-ref ref="RollingFile" />   
    </root> 



<! -- Log asynchronous to database -->  
<! - < appender name = "DB" class = "ch. Qos. Logback. Classic. DB. DBAppender" > asynchronous to the database log < connectionSource Class = "ch. Qos. Logback. Core. The DriverManagerConnectionSource" < > connection pool dataSource class="com.mchange.v2.c3p0.ComboPooledDataSource"> <driverClass>com.mysql.jdbc.Driver</driverClass> < url > JDBC: mysql: / / 127.0.0.1:3306 / databaseName < / url > < user > root < / user > < password > root < / password > < / a dataSource > </connectionSource> </appender> -->

</configuration>
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1.5 Eureka Cluster Deployment

Deployment environment: JDK1.8

Package projects
Upload the JAR package to the /usr/local/eureka folder

1.6 Writing startup Scripts

#! /bin/bashCD 'dirname $0' CUR_SHELL_DIR= 'PWD' CUR_SHELL_NAME= 'basename ${BASH_SOURCE}' JAR_NAME=" Project name" JAR_PATH=$CUR_SHELL_DIR/$JAR_NAME 
#JAVA_MEM_OPTS=" -server -Xms1024m -Xmx1024m -XX:PermSize=128m"JAVA_MEM_OPTS="" SPRING_PROFILES_ACTIV=" -dspring.profiles. active= Profile variable name"#SPRING_PROFILES_ACTIV=""LOG_DIR=$CUR_SHELL_DIR/logs LOG_PATH=$LOG_DIR/${JAR_NAME%.. log echo_help() { echo -e "syntax: sh $CUR_SHELL_NAME start|stop" } if [ -z $1 ]; then echo_help exit 1 fi if [ ! -d "$LOG_DIR" ]; then mkdir "$LOG_DIR" fi if [ ! -f "$LOG_PATH" ]; then touch "$LOG_DIR" fi if [ "$1" == "start" ]; then # check server PIDS=`ps --no-heading -C java -f --width 1000 | grep $JAR_NAME | awk '{print $2}'` if [ -n "$PIDS" ]; then echo -e "ERROR: The $JAR_NAME already started and the PID is ${PIDS}." exit 1 fi echo "Starting the $JAR_NAME..." # start nohup java $JAVA_MEM_OPTS -jar $SPRING_PROFILES_ACTIV $JAR_PATH >> $LOG_PATH 2>&1 & COUNT=0 while [ $COUNT -lt 1 ]; do sleep 1 COUNT=`ps --no-heading -C java -f --width 1000 | grep "$JAR_NAME" | awk '{print $2}' | wc -l` if [ $COUNT -gt 0]; then break fi done PIDS=`ps --no-heading -C java -f --width 1000 | grep "$JAR_NAME" | awk '{print $2}'` echo "${JAR_NAME} Started and the PID is ${PIDS}." echo "You can check the log file in ${LOG_PATH} for details." elif [ "$1" == "stop" ]; then PIDS=`ps --no-heading -C java -f --width 1000 | grep $JAR_NAME | awk '{print $2}'` if [ -z "$PIDS" ]; then echo "ERROR:The $JAR_NAME does not started!" exit 1 fi echo -e "Stopping the $JAR_NAME..." for PID in $PIDS; do kill $PID > /dev/null 2>&1 done COUNT=0 while [ $COUNT -lt 1 ]; do sleep 1 COUNT=1 for PID in $PIDS ; do PID_EXIST=`ps --no-heading -p $PID` if [ -n "$PID_EXIST" ]; then COUNT=0 break fi done done echo -e "${JAR_NAME} Stopped and the PID is ${PIDS}." else echo_help exit 1 fiCopy the code

Add permissions

chmod -R 755 server.sh

1.7 Modifying the hosts file on the Linux OS

vi /etc/hosts

192.168.234.130 eureka1
192.168.234.131 eureka2
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1.8 Start the Eureka registry

Sh start # Start./server.sh stop # StopCopy the code

4. Set up the Provider service in the highly available Eureka registry

1. Create projects

springcloud-eureka-provider

1.1 Adding a Dependency

<?xml version="1.0" encoding="UTF-8"? >
<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.13. RELEASE</version>
		<relativePath /> <! -- lookup parent from repository -->
	</parent>
	<groupId>com.luyi</groupId>
	<artifactId>springcloud-eureka-provider</artifactId>
	<version>0.0.1 - the SNAPSHOT</version>
	<name>springcloud-eureka-provider</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springframework.cloud</groupId>
				<artifactId>spring-cloud-dependencies</artifactId>
				<version>Dalston.SR5</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-config</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.cloud</groupId>
			<artifactId>spring-cloud-starter-eureka</artifactId>
		</dependency>
	</dependencies>
	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>
</project>
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1.2 Modifying the Startup Class

// Represents the client of Eureka
@EnableEurekaClient
@SpringBootApplication
public class EurekaApplication {
    public static void main(String[] args) { SpringApplication.run(EurekaApplication.class, args); }}Copy the code

1.3 Modifying the Provider Configuration File

Name =eureka-provider server.port=9090 To all the registry for registration eureka. Client. ServiceUrl. DefaultZone = http://eureka1:8761/eureka/, http://eureka2:8761/eureka/Copy the code

1.4 Modifying the Host file in Windows

C:\Windows\System32\drivers\etc

192.168.234.130 eureka1 192.168.234.131 eureka2

1.5 Writing service Interfaces

@RestController
public class UserController {

    @RequestMapping("/user")
    public List<User> getUsers(a){
        List<User> users = new ArrayList<>();
        users.add(new User(1."zhangsan".20));
        users.add(new User(2."lisi".22));
        users.add(new User(3."wangwu".30));
        returnusers; }}Copy the code

1.6 Creating Entities

/** * Author: LuYi * Date: 2019/11/6 12:30 * Description: Description */
public class User {

    private Integer userid;
    private String username;
    private Integer userage;

    public User(a) {}public User(Integer userid, String username, Integer userage) {
        this.userid = userid;
        this.username = username;
        this.userage = userage;
    }

    public Integer getUserid(a) {
        return userid;
    }

    public void setUserid(Integer userid) {
        this.userid = userid;
    }

    public String getUsername(a) {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getUserage(a) {
        return userage;
    }

    public void setUserage(Integer userage) {
        this.userage = userage; }}Copy the code

5. Set up Consumer services in the highly available Eureka registry

Both consumers and producers of services need to register with the Eureka registry

1. Create projects

1.1 Consumer profile

Name =eureka-consumer server.port=9091 To all the registry for registration eureka. Client. ServiceUrl. DefaultZone = http://eureka1:8761/eureka/, http://eureka2:8761/eureka/Copy the code

1.2 Complete Service Invocation in Service

@Service
public class UserService {

    @Autowired
    private LoadBalancerClient loadBalancerClient;  //ribbon: load balancer

    public List<User> getUsers(a){

        // Select the name of the service to invoke
            //ServiceInstance: encapsulates basic service information, such as the IP address and port number
        ServiceInstance si = loadBalancerClient.choose("eureka-provider");
        // Concatenate the URL to access the service
        StringBuffer sb = new StringBuffer();

        //http://localhost:9090/user
        sb.append("http://").append(si.getHost()).append(":").append(si.getPort()).append("/user");

        //SpringMVC RestTemplate
        RestTemplate restTemplate = new RestTemplate();
        ParameterizedTypeReference<List<User>> type = new ParameterizedTypeReference<List<User>>() {
        };

        //ResponseEntity: encapsulates the return value information
        ResponseEntity<List<User>> entity = restTemplate.exchange(sb.toString(), HttpMethod.GET, null, type);
        returnentity.getBody(); }}Copy the code

1.3 create a Controller

@RestController
public class UserController {

    @Autowired
    private UserService userService;

    @RequestMapping("/consumer")
    public List<User> getUsers(a){
        returnuserService.getUsers(); }}Copy the code

6. Architecture principle of Eureka Registry

1. Eureka architecture diagram

Register: Register your IP address and port number with Eureka
Renew: Send heartbeat packets every 30 seconds to tell Eureka that they are alive
Cancel: When the provider is closed, it sends a message to Eureka to remove itself from the list of services. Prevents a Consumer from invoking a service that doesn’t exist
Get Registry: Get a list of other services
Replicate (Data synchronization in a Cluster) : Data replication and synchronization in a Eureka cluster
Make Remote Call: Complete the service Remote Call

7. Based on the distributed CAP theorem, this paper analyzes the differences between the two mainstream frameworks of registry: Eureka and Zookeeper

1. What are the CAP principles

The CAP principle, also known as the CAP theorem, refers to Consistency, Availability and Partition tolerance in distributed systems.

CAP was proposed by Eric Brewer at PODC 2000. The conjecture proved true two years later and became known as the CAP theorem

2. Differences between Zookeeper and Eureka

8. Eureka’s elegant stop service

1. Under what circumstances does Eureka turn on self-protection

1.1 Self-protection conditions

Generally, after Eureka is registered, the microserver sends heartbeat packets every 30 seconds, and deletes services that do not send heartbeat packets in the 90s periodically.

1.2 There are two conditions in which The Eureka Server cannot receive the heartbeat of the microservice

Microservices themselves
The reason for the network between microservices and Eureka

If a microservice fault occurs, a large number of heartbeat packets cannot be received, but only some faults occur. However, a network fault causes a large number of heartbeat packets cannot be received.

Considering this difference, Eureka sets a threshold. If a large number of heartbeat packets are not received within a short period of time, it will be judged as a network fault. In this way, Eureka will not delete the service whose heartbeat has expired
So what’s the threshold

Determine if it is below 85% within 15 minutes

Eureka Server determines whether 85% of heartbeat failures occur within 15 minutes

This algorithm is called Eureka Server’s self-protection mode.

2. Why protect yourself

Because it is better to keep ** good data and ** bad data than to delete all data, if you enter self-protection mode because of network failure, when the fault is repaired, it will automatically exit self-protection mode
The load balancing policy of microservice automatically removes dead microservice nodes

3. How do I turn off self-protection

Example Modify the Eureka Server configuration file

Eureka.server. enable-self-preservation=false eureka.server.enable-self-preservation=false Ms, default is 60*1000) Eureka. server.eviction- interval-timer-in-MS =60000Copy the code

4. 4. Smart Laundry peg

4.1 You do not need to disable self-protection in Eureka Server

4.2 Adding the skeleton.jar package to services

4.3 Modifying the Configuration File

# start shutdown endpoints. Shutdown. Enabled = true # disabled password authentication endpoints. The shutdown. The sensitive = falseCopy the code

4.4 Send a URL request to disable the service

public class HttpClientUtil {

	public static String doGet(String url, Map<String, String> param) {

		// Create an Httpclient object
		CloseableHttpClient httpclient = HttpClients.createDefault();

		String resultString = "";
		CloseableHttpResponse response = null;
		try {
			/ / create a uri
			URIBuilder builder = new URIBuilder(url);
			if(param ! =null) {
				for (String key : param.keySet()) {
					builder.addParameter(key, param.get(key));
				}
			}
			URI uri = builder.build();

			// Create an HTTP GET request
			HttpGet httpGet = new HttpGet(uri);

			// Execute the request
			response = httpclient.execute(httpGet);
			// Check whether the return status is 200
			if (response.getStatusLine().getStatusCode() == 200) {
				resultString = EntityUtils.toString(response.getEntity(), "UTF-8"); }}catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				if(response ! =null) {
					response.close();
				}
				httpclient.close();
			} catch(IOException e) { e.printStackTrace(); }}return resultString;
	}

	public static String doGet(String url) {
		return doGet(url, null);
	}

	public static String doPost(String url, Map<String, String> param) {
		// Create an Httpclient object
		CloseableHttpClient httpClient = HttpClients.createDefault();
		CloseableHttpResponse response = null;
		String resultString = "";
		try {
			// Create an Http Post request
			HttpPost httpPost = new HttpPost(url);
			// Create a parameter list
			if(param ! =null) {
				List<NameValuePair> paramList = new ArrayList<>();
				for (String key : param.keySet()) {
					paramList.add(new BasicNameValuePair(key, param.get(key)));
				}
				// Simulate the form
				UrlEncodedFormEntity entity = new UrlEncodedFormEntity(paramList,"utf-8");
				httpPost.setEntity(entity);
			}
			// Execute the HTTP request
			response = httpClient.execute(httpPost);
			resultString = EntityUtils.toString(response.getEntity(), "utf-8");
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				response.close();
			} catch (IOException e) {
				// TODO Auto-generated catch blocke.printStackTrace(); }}return resultString;
	}

	public static String doPost(String url) {
		return doPost(url, null);
	}
	
	public static String doPostJson(String url, String json) {
		// Create an Httpclient object
		CloseableHttpClient httpClient = HttpClients.createDefault();
		CloseableHttpResponse response = null;
		String resultString = "";
		try {
			// Create an Http Post request
			HttpPost httpPost = new HttpPost(url);
			// Create the requested content
			StringEntity entity = new StringEntity(json, ContentType.APPLICATION_JSON);
			httpPost.setEntity(entity);
			// Execute the HTTP request
			response = httpClient.execute(httpPost);
			resultString = EntityUtils.toString(response.getEntity(), "utf-8");
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				response.close();
			} catch (IOException e) {
				// TODO Auto-generated catch blocke.printStackTrace(); }}return resultString;
	}
	
	public static void main(String[] args) {
		String url ="http://127.0.0.1:9090/shutdown";
		// This URL must be sent in doPost modeHttpClientUtil.doPost(url); }}Copy the code

How to strengthen Eureka registration center security certification

1. Add the security package to EurekaServer

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
</dependency>
Copy the code

2. Modify the Eureka Server configuration file

Security.basic. enabled=true security.user.name=user security.user.password=123456Copy the code

3. Change the url for accessing the cluster node

eureka.client.serviceUrl.defaultZone=http://user:123456@eureka2:8761/eureka/
Copy the code

4. Modify the configuration file to change the user name and password for accessing the registry

Name =eureka-provider server.port=9090 Register with all registries eureka.client.serviceUrl.defaultZone=http://user:123456@eureka1:8761/eureka/,http://user:123456@eureka2:8761/eureka/ # start shutdown endpoints. Shutdown. Enabled = true # disabled password authentication endpoints. The shutdown. The sensitive = falseCopy the code

Learn SpringCloud Eureka to take you from zero to one

What is a Service registry

1. The role of the service registry

2. Common registry

3. What problems do service registries solve

4. What is the Eureka Registry

4.1 Three roles in the Eureka Registry

2. Introduction to Eureka

1. Create projects

1.1 Adding a Dependency

1.2 Modifying the Startup Class

1.3 Modifying the Global Configuration File

1.4 Accessing the Eureka-Server Service Management Platform using a Browser

3. Build Eureka cluster

1. Create projects

1.1 Creating a Project

1.2 Modifying the Configuration File

1.3 Configuring cluster Nodes in the Configuration file

1.4 Adding the LogBack Log Configuration File

1.5 Eureka Cluster Deployment

1.6 Writing startup Scripts

1.7 Modifying the hosts file on the Linux OS

1.8 Start the Eureka registry

4. Set up the Provider service in the highly available Eureka registry

1. Create projects

1.1 Adding a Dependency

1.2 Modifying the Startup Class

1.3 Modifying the Provider Configuration File

1.4 Modifying the Host file in Windows

1.5 Writing service Interfaces

1.6 Creating Entities

5. Set up Consumer services in the highly available Eureka registry

1. Create projects

1.1 Consumer profile

1.2 Complete Service Invocation in Service

1.3 create a Controller

6. Architecture principle of Eureka Registry

1. Eureka architecture diagram

7. Based on the distributed CAP theorem, this paper analyzes the differences between the two mainstream frameworks of registry: Eureka and Zookeeper

1. What are the CAP principles

2. Differences between Zookeeper and Eureka

8. Eureka’s elegant stop service

1. Under what circumstances does Eureka turn on self-protection

1.1 Self-protection conditions

1.2 There are two conditions in which The Eureka Server cannot receive the heartbeat of the microservice

2. Why protect yourself

3. How do I turn off self-protection

4. 4. Smart Laundry peg

4.1 You do not need to disable self-protection in Eureka Server

4.2 Adding the skeleton.jar package to services

4.3 Modifying the Configuration File

4.4 Send a URL request to disable the service

How to strengthen Eureka registration center security certification

1. Add the security package to EurekaServer

2. Modify the Eureka Server configuration file

3. Change the url for accessing the cluster node

4. Modify the configuration file to change the user name and password for accessing the registry

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