学习部署微服务。第1部分。SpringBoot和Docker

哈Ha

在本文中，我想谈谈我为微服务实验创建学习环境的经验。在研究每个新工具时，我一直想不仅在本地计算机上尝试它，而且还要在更实际的条件下尝试它。因此，我决定创建一个简化的微服务应用程序，随后可以使用各种有趣的技术对其进行“加权”。该项目的主要要求是其最大程度地接近实际系统。

最初，我将项目的创建分为几个步骤：

1. — '' (backend) '' (gateway), docker-

   
   

   : Java 11, Spring Boot, Docker, image optimization

   
   

2. Kubernetes Google Kubernetes Engine

   
   

   : Kubernetes, GKE, resource management, autoscaling, secrets

   
   

3. Helm 3

   
   

   : Helm 3, chart deployment

   
   

4. Jenkins

   
   

   : Jenkins configuration, plugins, separate configs repository

   
   

.

, , . , , 20% (, , 80% ). , , , . .

Java 11 Spring Boot. REST. ( , Jenkins). GitHub: .

, Spring Actuator. /actuator/health 200 , , 504 . , , - , . Actuator , . , , , .

Backend

.

:

@RestController
public class RequestsCounterController {

    private final AtomicLong counter = new AtomicLong();

    @GetMapping("/requests")
    public Long getRequestsCount() {
        return counter.incrementAndGet();
    }
}

:

@WebMvcTest(RequestsCounterController.class)
public class RequestsCounterControllerTests {

    @Autowired
    private MockMvc mockMvc;

    @Test
    public void firstRequest_one() throws Exception {
        mockMvc.perform(get("/requests"))
            .andExpect(status().isOk())
            .andExpect(MockMvcResultMatchers.content().string("1"));
    }
}

Gateway

, :

• id . ,
• "", (№ )

application.properties:

backend.url=http://localhost:8081
instance.id=${random.int}
secret="default-secret"

:

@Service
public class BackendAdapter {

    private static final String REQUESTS_ENDPOINT = "/requests";

    private final RestTemplate restTemplate;

    @Value("${backend.url}")
    private String backendUrl;

    public BackendAdapter(RestTemplateBuilder builder) {
        restTemplate = builder.build();
    }

    public String getRequests() {
        ResponseEntity<String> response = restTemplate.getForEntity(
backendUrl + REQUESTS_ENDPOINT, String.class);
        return response.getBody();
    }
}

:

@RestController
@RequiredArgsConstructor
public class EndpointController {

    private final BackendAdapter backendAdapter;

    @Value("${instance.id}")
    private int instanceId;

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

    @GetMapping("/")
    public String getRequestsCount() {
        return String.format("Number of requests %s (gateway %d, secret %s)", backendAdapter.getRequests(), instanceId, secret);
    }
}

:

:

./mvnw package -DskipTests
java -Dserver.port=8081 -jar target/microservices-backend-1.0.0.jar

:

./mvnw package -DskipTests
java -jar target/microservices-gateway-1.0.0.jar

:

$ curl http://localhost:8080/
Number of requests 1 (gateway 38560358, secret "default-secret")

. , (http://localhost:8081/requests). , , "" .
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Docker

, , . , Dockerfile — . , (№ DockerHub) .

Dockerfile

— . , , . , . Alpine — Linux .

Dockerfile " " ( , , ):

FROM adoptopenjdk/openjdk11:jdk-11.0.5_10-alpine
ADD . /src
WORKDIR /src
RUN ./mvnw package -DskipTests
EXPOSE 8080
ENTRYPOINT ["java","-jar","target/microservices-gateway-1.0.0.jar"]

Alpine JDK . ADD src, (WORKDIR) . EXPOSE 8080 , 8080 ( , , , ).

:

docker image build . -t msvc-backend:1.0.0

456 ( JDK 340 ). , . :

• . , JRE, Alpine . .
• java. Java 9, jlink JRE

, https://habr.com/ru/company/ruvds/blog/485650/.

Dockerfile:

FROM adoptopenjdk/openjdk11:jdk-11.0.5_10-alpine as builder
ADD . /src
WORKDIR /src
RUN ./mvnw package -DskipTests

FROM alpine:3.10.3 as packager
RUN apk --no-cache add openjdk11-jdk openjdk11-jmods
ENV JAVA_MINIMAL="/opt/java-minimal"
RUN /usr/lib/jvm/java-11-openjdk/bin/jlink \
    --verbose \
    --add-modules \
        java.base,java.sql,java.naming,java.desktop,java.management,java.security.jgss,java.instrument \
    --compress 2 --strip-debug --no-header-files --no-man-pages \
    --release-info="add:IMPLEMENTOR=radistao:IMPLEMENTOR_VERSION=radistao_JRE" \
    --output "$JAVA_MINIMAL"

FROM alpine:3.10.3
LABEL maintainer="Anton Shelenkov anshelen@yandex.ru"
ENV JAVA_HOME=/opt/java-minimal
ENV PATH="$PATH:$JAVA_HOME/bin"
COPY --from=packager "$JAVA_HOME" "$JAVA_HOME"
COPY --from=builder /src/target/microservices-backend-*.jar app.jar
EXPOSE 8080
ENTRYPOINT ["java","-jar","/app.jar"]

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Docker

. , — bridge, , . :

docker network create msvc-network

'backend' microservices-backend:1.0.0:

docker run -dit --name backend --network msvc-net microservices-backend:1.0.0

, bridge- service discovery . http://backend:8080.

:

docker run -dit -p 80:8080 --env secret=my-real-secret --env BACKEND_URL=http://backend:8080/ --name gateway --network msvc-net microservices-gateway:1.0.0

, 80 8080 . env , application.properties.

http://localhost/ , , .

, - . , , :

• —
• —
• — 3 , ( 2 )

为了解决上述问题，有许多解决方案，例如Docker Swarm，Nomad，Kubernetes或OpenShift。如果整个系统将用Java编写，那么您可以参考Spring Cloud（一篇不错的文章）。

在接下来的部分，我就说说我是如何配置Kubernetes和部署项目到谷歌Kubernetes引擎。