（给ImportNew加星标，提高Java技能）

在本文中，您将了解在 Kubernetes 上运行 Java 应用程序的最佳实践。大多数这些建议也适用于其他语言。但是，我正在考虑 Java 特性范围内的所有规则，并且还展示了可用于基于 JVM 的应用程序的解决方案和工具。当使用最流行的 Java 框架（如 Spring Boot 或 Quarkus）时，这些 Kubernetes 建议中的一些是设计强制的。我将向您展示如何有效地利用它们来简化开发人员的生活。

1、不要将 Limit 设置得太低

2、首先考虑内存使用

3、适当的 liveness 和 readiness 探针

3.1 介绍

3.2 配置详情

management:  endpoint:     health:      probes:        enabled: true

spring:  application:    name: sample-spring-boot-on-kubernetes  data:    mongodb:      host: ${MONGO_URL}      port: 27017      username: ${MONGO_USERNAME}      password: ${MONGO_PASSWORD}      database: ${MONGO_DATABASE}      authentication-database: admin
management:  endpoint.health:    show-details: always    group:      readiness:        include: mongo # (1)        additional-path: server:/readiness # (2)    probes:      enabled: true  server:    port: 8081

spring:  application:    name: sample-spring-kotlin-microservice  datasource:    url: jdbc:postgresql://postgres:5432/postgres    username: postgres    password: postgres123    hikari:      connection-timeout: 2000      initialization-fail-timeout: 0  jpa:    database-platform: org.hibernate.dialect.PostgreSQLDialect  rabbitmq:    host: rabbitmq    port: 5672    connection-timeout: 2000

4、选择合适的 JDK

apiVersion: skaffold/v2beta22kind: Configmetadata:  name: sample-spring-boot-on-kubernetesbuild:  artifacts:    - image: piomin/sample-spring-boot-on-kubernetes      buildpacks:        builder: paketobuildpacks/builder:base        buildpacks:          - paketo-buildpacks/amazon-corretto          - paketo-buildpacks/java        env:          - BP_JVM_VERSION=17

5、考虑迁移到原生编译

<profiles>  <profile>    <id>native</id>    <activation>      <property>        <name>native</name>      </property>    </activation>    <properties>      <skipITs>false</skipITs>      <quarkus.package.type>native</quarkus.package.type>    </properties>  </profile></profiles>

$ mvn clean package -Pnative

<plugin>  <groupId>org.springframework.boot</groupId>  <artifactId>spring-boot-maven-plugin</artifactId>  <executions>    <execution>      <goals>        <goal>build-info</goal>        <goal>build-image</goal>      </goals>    </execution>  </executions>  <configuration>    <image>      <builder>paketobuildpacks/builder:tiny</builder>      <env>        <BP_NATIVE_IMAGE>true</BP_NATIVE_IMAGE>        <BP_NATIVE_IMAGE_BUILD_ARGUMENTS>          --allow-incomplete-classpath        </BP_NATIVE_IMAGE_BUILD_ARGUMENTS>      </env>    </image>  </configuration></plugin>

6、正确配置日志记录

<dependency>   <groupId>net.logstash.logback</groupId>   <artifactId>logstash-logback-encoder</artifactId>   <version>7.2</version></dependency>

<configuration>    <appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender">        <encoder class="net.logstash.logback.encoder.LogstashEncoder"/>    </appender>    <logger name="jsonLogger" additivity="false" level="DEBUG">        <appender-ref ref="consoleAppender"/>    </logger>    <root level="INFO">        <appender-ref ref="consoleAppender"/>    </root></configuration>

<dependency>  <groupId>org.springframework.boot</groupId>  <artifactId>spring-boot-starter-amqp</artifactId></dependency>

<?xml version="1.0" encoding="UTF-8"?><configuration>
  <springProperty name="destination" source="app.amqp.url" />
  <appender name="AMQP"    class="org.springframework.amqp.rabbit.logback.AmqpAppender">    <layout>      <pattern>{  "time": "%date{ISO8601}",  "thread": "%thread",  "level": "%level",  "class": "%logger{36}",  "message": "%message"}      </pattern>    </layout>
    <addresses>${destination}</addresses>      <applicationId>api-service</applicationId>    <routingKeyPattern>logs</routingKeyPattern>    <declareExchange>true</declareExchange>    <exchangeName>ex_logstash</exchangeName>
  </appender>
  <root level="INFO">    <appender-ref ref="AMQP" />  </root>
</configuration>

7、创建集成测试

<dependency>   <groupId>io.quarkus</groupId>   <artifactId>quarkus-container-image-jib</artifactId></dependency>

@QuarkusIntegrationTestpublic class EmployeeControllerIT {
    @TestHTTPEndpoint(EmployeeController.class)    @TestHTTPResource    URL url;
    @Test    void add() {        EmployeeService service = RestClientBuilder.newBuilder()                .baseUrl(url)                .build(EmployeeService.class);        Employee employee = new Employee(1L, 1L, "Josh Stevens",                                          23, "Developer");        employee = service.add(employee);        assertNotNull(employee.getId());    }
    @Test    public void findAll() {        EmployeeService service = RestClientBuilder.newBuilder()                .baseUrl(url)                .build(EmployeeService.class);        Set<Employee> employees = service.findAll();        assertTrue(employees.size() >= 3);    }
    @Test    public void findById() {        EmployeeService service = RestClientBuilder.newBuilder()                .baseUrl(url)                .build(EmployeeService.class);        Employee employee = service.findById(1L);        assertNotNull(employee.getId());    }}

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)@Testcontainers@TestMethodOrder(MethodOrderer.OrderAnnotation.class)public class PersonControllerTests {
    @Autowired    TestRestTemplate restTemplate;
    @Container    static PostgreSQLContainer<?> postgres =        new PostgreSQLContainer<>("postgres:15.1")            .withExposedPorts(5432);
    @DynamicPropertySource    static void registerMySQLProperties(DynamicPropertyRegistry registry) {        registry.add("spring.datasource.url", postgres::getJdbcUrl);        registry.add("spring.datasource.username", postgres::getUsername);        registry.add("spring.datasource.password", postgres::getPassword);    }
    @Test    @Order(1)    void add() {        Person person = Instancio.of(Person.class)                .ignore(Select.field("id"))                .create();        person = restTemplate.postForObject("/persons", person, Person.class);        Assertions.assertNotNull(person);        Assertions.assertNotNull(person.getId());    }
    @Test    @Order(2)    void updateAndGet() {        final Integer id = 1;        Person person = Instancio.of(Person.class)                .set(Select.field("id"), id)                .create();        restTemplate.put("/persons", person);        Person updated = restTemplate.getForObject("/persons/{id}", Person.class, id);        Assertions.assertNotNull(updated);        Assertions.assertNotNull(updated.getId());        Assertions.assertEquals(id, updated.getId());    }
}

8、最后的想法

转自：云云众生s / 岱军，

英文链接：piotrminkowski.com/2023/02/13/best-practices-for-java-apps-on-kubernetes/

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