Spring Boot

https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle/
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Spring Boot makes it easy to create stand-alone, production-grade Spring-based applications that you...
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### Start Spring Boot init.d service on Debian

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Start the installed service using the service command on Debian-based systems. If startup fails, check /var/log/<appname>.log for errors.

```bash
$ service myapp start
```

--------------------------------

### myapp.conf configuration file example

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Example .conf file for customizing script settings. It sets JAVA_OPTS and LOG_FOLDER. The file should be named the same as the jar but with .conf suffix and placed next to the jar file.

```plaintext
JAVA_OPTS=-Xmx1024M
LOG_FOLDER=/custom/log/folder
```

--------------------------------

### Enable systemd service to start on boot

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Run this command to flag the application to start automatically on system boot. Refer to man systemctl for more details.

```bash
$ systemctl enable myapp.service

```

--------------------------------

### Boxfuse deployment output example

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Example output from `boxfuse run` showing the steps of fusing an image, creating AWS resources, and deploying. The output includes timings, resource IDs, and the final URL. This is the expected output when the command succeeds.

```text
Fusing Image for myapp-1.0.jar ...
Image fused in 00:06.838s (53937 K) -> axelfontaine/myapp:1.0
Creating axelfontaine/myapp ...
Pushing axelfontaine/myapp:1.0 ...
Verifying axelfontaine/myapp:1.0 ...
Creating Elastic IP ...
Mapping myapp-axelfontaine.boxfuse.io to 52.28.233.167 ...
Waiting for AWS to create an AMI for axelfontaine/myapp:1.0 in eu-central-1 (this may take up to 50 seconds) ...
AMI created in 00:23.557s -> ami-d23f38cf
Creating security group boxfuse-sg_axelfontaine/myapp:1.0 ...
Launching t2.micro instance of axelfontaine/myapp:1.0 (ami-d23f38cf) in eu-central-1 ...
Instance launched in 00:30.306s -> i-92ef9f53
Waiting for AWS to boot Instance i-92ef9f53 and Payload to start at https://52.28.235.61/ ...
Payload started in 00:29.266s -> https://52.28.235.61/
Remapping Elastic IP 52.28.233.167 to i-92ef9f53 ...
Waiting 15s for AWS to complete Elastic IP Zero Downtime transition ...
Deployment completed successfully. axelfontaine/myapp:1.0 is up and running at https://myapp-axelfontaine.boxfuse.io/
```

--------------------------------

### Start Ant with -lib option

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Command to start Ant with the -lib option pointing to the folder containing the spring-boot-antlib jar. Required for the Antlib to be available.

```shell
$ ant -lib <folder containing spring-boot-antlib-2.2.7.RELEASE.jar>
```

--------------------------------

### Install Spring Boot CLI with Scoop

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Install the Spring Boot CLI on Windows using Scoop. The `spring` command is installed to `~/scoop/apps/springboot/current/bin`.

```powershell
> scoop bucket add extras
> scoop install springboot

```

--------------------------------

### spring install com.example:spring-boot-cli-extension:1.0.0.RELEASE

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Installs a CLI extension using artifact coordinates in the format group:artifact:version. All dependencies of the artifact are also installed.

```bash
$ spring install com.example:spring-boot-cli-extension:1.0.0.RELEASE

```

--------------------------------

### Equivalent application.properties for YAML example

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

The application.properties equivalent of the preceding YAML example. Shows the flattened, period-separated keys.

```properties
spring.application.name=cruncher
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost/test
server.port=9000
```

--------------------------------

### Install Spring Boot CLI with SDKMAN!

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Use SDKMAN! to install the Spring Boot CLI and verify the version. The output shows Spring Boot v2.2.7.RELEASE.

```bash
$ sdk install springboot
$ spring --version
Spring Boot v2.2.7.RELEASE

```

--------------------------------

### Install dev instance of Spring Boot CLI with SDKMAN!

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Install a local 'dev' instance pointing to your built Spring Boot CLI. The output shows Spring CLI v2.2.7.RELEASE.

```bash
$ sdk install springboot dev /path/to/spring-boot/spring-boot-cli/target/spring-boot-cli-2.2.7.RELEASE-bin/spring-2.2.7.RELEASE/
$ sdk default springboot dev
$ spring --version
Spring CLI v2.2.7.RELEASE

```

--------------------------------

### List installed Spring Boot CLI versions with SDKMAN!

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Shows the output of `sdk ls springboot`, listing the local 'dev' instance and the installed 2.2.7.RELEASE version.

```bash
$ sdk ls springboot

================================================================================
Available Springboot Versions
================================================================================
> + dev
* 2.2.7.RELEASE

================================================================================
+ - local version
* - installed
> - currently in use
================================================================================

```

--------------------------------

### Console log color conversion example

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Shows how to specify a color for a log conversion pattern using the %clr conversion word. The example makes the timestamp yellow.

```plaintext
%clr(%d{yyyy-MM-dd HH:mm:ss.SSS}){yellow}
```

--------------------------------

### spring init --dependencies=web,data-jpa my-project

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Creates a new project using start.spring.io. The example creates a Maven-based project with spring-boot-starter-web and spring-boot-starter-data-jpa in a my-project directory. Output shows the service URL and extraction path.

```bash
$ spring init --dependencies=web,data-jpa my-project
Using service at https://start.spring.io
Project extracted to '/Users/developer/example/my-project'

```

--------------------------------

### Injecting RSocketRequester.Builder in a service

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Example of injecting RSocketRequester.Builder as a prototype bean and connecting to a TCP server. The builder is stateful, so each injection point gets a new instance.

```java
@Service
public class MyService {

    private final Mono<RSocketRequester> rsocketRequester;

    public MyService(RSocketRequester.Builder rsocketRequesterBuilder) {
        this.rsocketRequester = rsocketRequesterBuilder
                .connectTcp("example.org", 9898).cache();
    }

    public Mono<User> someRSocketCall(String name) {
        return this.rsocketRequester.flatMap(req ->
                    req.route("user").data(name).retrieveMono(User.class));
    }

}
```

--------------------------------

### Create Example.java with Spring Boot annotations

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Create this Java file at src/main/java/Example.java to define a simple web controller. The @RestController and @RequestMapping annotations handle web requests, while @EnableAutoConfiguration configures Spring based on dependencies. The main method delegates to SpringApplication.run to bootstrap the application.

```java
import org.springframework.boot.*;
import org.springframework.boot.autoconfigure.*;
import org.springframework.web.bind.annotation.*;

@RestController
@EnableAutoConfiguration
public class Example {

    @RequestMapping("/")
    String home() {
        return "Hello World!";
    }

    public static void main(String[] args) {
        SpringApplication.run(Example.class, args);
    }

}
```

--------------------------------

### MockMvc test with @WebMvcTest

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Use @WebMvcTest to test a single controller with MockMvc, mocking collaborators with @MockBean. The example verifies a GET request returns expected text.

```java
import org.junit.jupiter.api.*;
import org.springframework.beans.factory.annotation.*;
import org.springframework.boot.test.autoconfigure.web.servlet.*;
import org.springframework.boot.test.mock.mockito.*;

import static org.assertj.core.api.Assertions.*;
import static org.mockito.BDDMockito.*;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.*;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;

@WebMvcTest(UserVehicleController.class)
class MyControllerTests {

    @Autowired
    private MockMvc mvc;

    @MockBean
    private UserVehicleService userVehicleService;

    @Test
    void testExample() throws Exception {
        given(this.userVehicleService.getVehicleDetails("sboot"))
                .willReturn(new VehicleDetails("Honda", "Civic"));
        this.mvc.perform(get("/sboot/vehicle").accept(MediaType.TEXT_PLAIN))
                .andExpect(status().isOk()).andExpect(content().string("Honda Civic"));
    }

}
```

--------------------------------

### Externalize SpringApplication configuration with spring.main.*

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Example application.properties settings that disable the web application type and banner mode, preventing the banner from printing and the embedded web server from starting.

```properties
spring.main.web-application-type=none
spring.main.banner-mode=off

```

--------------------------------

### Create init.d symlink for Spring Boot application

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Symlink the executable jar to /etc/init.d to enable standard start, stop, restart, and status commands. The application is assumed to be installed in /var/myapp.

```bash
$ sudo ln -s /var/myapp/myapp.jar /etc/init.d/myapp
```

--------------------------------

### application.properties example for server.port and server.address

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Shows how to set the server.port and server.address properties in application.properties. These properties are part of the server group.

```properties
server.port=9090
server.address=127.0.0.1
```

--------------------------------

### WebTestClient test with @AutoConfigureWebTestClient

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Use @SpringBootTest with @AutoConfigureWebTestClient to inject a WebTestClient for testing reactive web applications. The example performs a GET request to '/' and expects status 200 and body 'Hello World'.

```java
import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.reactive.AutoConfigureWebTestClient;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.reactive.server.WebTestClient;

@SpringBootTest
@AutoConfigureWebTestClient
class MockWebTestClientExampleTests {

    @Test
    void exampleTest(@Autowired WebTestClient webClient) {
        webClient.get().uri("/").exchange().expectStatus().isOk().expectBody(String.class).isEqualTo("Hello World");
    }

}
```

--------------------------------

### Configuration properties class with Javadoc

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Example of a @ConfigurationProperties class with Javadoc on each field. Use a unique namespace (e.g., 'acme') and document keys with field Javadoc. For boolean types, start descriptions with 'Whether' or 'Enable'.

```java
@ConfigurationProperties("acme")
public class AcmeProperties {

    /**
     * Whether to check the location of acme resources.
     */
    private boolean checkLocation = true;

    /**
     * Timeout for establishing a connection to the acme server.
     */
    private Duration loginTimeout = Duration.ofSeconds(3);

    // getters & setters

}
```

--------------------------------

### spring init --list

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Lists the capabilities of the start.spring.io service, including available dependencies and project types. The output shows a partial list with the default project type maven-project.

```bash
$ spring init --list
=======================================
Capabilities of https://start.spring.io
=======================================

Available dependencies:
-----------------------
actuator - Actuator: Production ready features to help you monitor and manage your application
...
web - Web: Support for full-stack web development, including Tomcat and spring-webmvc
websocket - Websocket: Support for WebSocket development
ws - WS: Support for Spring Web Services

Available project types:
------------------------
gradle-build -  Gradle Config [format:build, build:gradle]
gradle-project -  Gradle Project [format:project, build:gradle]
maven-build -  Maven POM [format:build, build:maven]
maven-project -  Maven Project [format:project, build:maven] (default)

...

```

--------------------------------

### spring init --build=gradle --java-version=1.8 --dependencies=websocket --packaging=war sample-app.zip

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Creates a Gradle project using Java 8 and war packaging with the websocket dependency. The output shows the service URL and that the content was saved to sample-app.zip.

```bash
$ spring init --build=gradle --java-version=1.8 --dependencies=websocket --packaging=war sample-app.zip
Using service at https://start.spring.io
Content saved to 'sample-app.zip'

```

--------------------------------

### TestRestTemplate test with RANDOM_PORT

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Use @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT) with TestRestTemplate to make REST calls to a running server without spring-webflux. The example performs a GET request and asserts the response body equals 'Hello World'.

```java
import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
import org.springframework.boot.test.web.client.TestRestTemplate;

import static org.assertj.core.api.Assertions.assertThat;

@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class RandomPortTestRestTemplateExampleTests {

    @Test
    void exampleTest(@Autowired TestRestTemplate restTemplate) {
        String body = restTemplate.getForObject("/", String.class);
        assertThat(body).isEqualTo("Hello World");
    }

}
```

--------------------------------

### Startup Failure Message for Port 8080 in Use

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Example of a failure message produced by FailureAnalyzers when the embedded servlet container fails to start because port 8080 is already in use. The message includes a description and an action to resolve the issue.

```text
***************************
APPLICATION FAILED TO START
***************************

Description:

Embedded servlet container failed to start. Port 8080 was already in use.

Action:

Identify and stop the process that's listening on port 8080 or configure this application to listen on another port.
```

--------------------------------

### Typical Spring Boot project layout

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Shows a recommended package structure with a root application class and sub-packages for customer and order domains.

```text
com
 +- example
     +- myapplication
         +- Application.java
         |
         +- customer
         |   +- Customer.java
         |   +- CustomerController.java
         |   +- CustomerService.java
         |   +- CustomerRepository.java
         |
         +- order
             +- Order.java
             +- OrderController.java
             +- OrderService.java
             +- OrderRepository.java
```

--------------------------------

### MockMvc test with @SpringBootTest and @AutoConfigureMockMvc

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Use @SpringBootTest with @AutoConfigureMockMvc to test the web layer by injecting MockMvc. The example performs a GET request to '/' and expects status 200 and content 'Hello World'. For web layer only, consider @WebMvcTest instead.

```java
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.servlet.MockMvc;

import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

@SpringBootTest
@AutoConfigureMockMvc
class MockMvcExampleTests {

    @Test
    void exampleTest(@Autowired MockMvc mvc) throws Exception {
        mvc.perform(get("/")).andExpect(status().isOk()).andExpect(content().string("Hello World"));
    }

}
```

--------------------------------

### Add spring-boot-starter-web for logging (Maven)

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Adds the web starter which transitively includes spring-boot-starter-logging, providing Logback and spring-jcl on the classpath.

```xml
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
```

--------------------------------

### Auto-configured Spring REST Docs test with WebTestClient

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Use @AutoConfigureRestDocs with @WebFluxTest to automatically configure WebTestClient for Spring REST Docs. Inject WebTestClient with @Autowired and use it as usual. The example shows a test that performs a GET request and documents the result with the 'list-users' identifier.

```java
import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.restdocs.AutoConfigureRestDocs;
import org.springframework.boot.test.autoconfigure.web.reactive.WebFluxTest;
import org.springframework.test.web.reactive.server.WebTestClient;

import static org.springframework.restdocs.webtestclient.WebTestClientRestDocumentation.document;

@WebFluxTest
@AutoConfigureRestDocs
class UsersDocumentationTests {

    @Autowired
    private WebTestClient webTestClient;

    @Test
    void listUsers() {
        this.webTestClient.get().uri("/").exchange().expectStatus().isOk().expectBody()
                .consumeWith(document("list-users"));
    }

}
```

--------------------------------

### Run the executable jar with java -jar

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Starts the application from the packaged jar. The output shows the Spring Boot banner and a startup log line with the application name and startup time.

```bash
$ java -jar target/myproject-0.0.1-SNAPSHOT.jar

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::  (v2.2.7.RELEASE)
....... . . .
....... . . . (log output here)
....... . . .
........ Started Example in 2.536 seconds (JVM running for 2.864)
```

--------------------------------

### Auto-configured Spring REST Docs test with Mock MVC

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Use @AutoConfigureRestDocs with @WebMvcTest to automatically configure MockMvc for Spring REST Docs. Inject MockMvc with @Autowired and use it as usual. The example shows a test that performs a GET request and documents the result with the 'list-users' identifier.

```java
import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.http.MediaType;
import org.springframework.test.web.servlet.MockMvc;

import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.document;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;

@WebMvcTest(UserController.class)
@AutoConfigureRestDocs
class UserDocumentationTests {

    @Autowired
    private MockMvc mvc;

    @Test
    void listUsers() throws Exception {
        this.mvc.perform(get("/users").accept(MediaType.TEXT_PLAIN))
                .andExpect(status().isOk())
                .andDo(document("list-users"));
    }

}
```

--------------------------------

### Create single instance environment with eb create -s

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Use this CLI command to create a single instance environment, avoiding the cost of a load balancer.

```bash
eb create -s
```

--------------------------------

### Install Spring Boot CLI with Homebrew

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Install the Spring Boot CLI on macOS using Homebrew. The `spring` command is installed to `/usr/local/bin`.

```bash
$ brew tap pivotal/tap
$ brew install springboot

```

--------------------------------

### Configure auto-start for init.d service on Debian

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Use update-rc.d to flag the application to start automatically. Replace <priority> with the desired startup priority.

```bash
$ update-rc.d myapp defaults <priority>
```

--------------------------------

### Any provider example for system.state

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

JSON metadata snippet showing the 'any' provider for the 'system.state' property, offering 'on' and 'off' as auto-completion values while allowing any other value.

```json
{"hints": [
    {
        "name": "system.state",
        "values": [
            {
                "value": "on"
            },
            {
                "value": "off"
            }
        ],
        "providers": [
            {
                "name": "any"
            }
        ]
    }
]}
```

--------------------------------

### Repackage Implementation Example

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Shows a typical repackage implementation using Repackager and Libraries. It sets backupSource to false and provides a Libraries implementation with a doWithLibraries method for build-system-specific dependency handling.

```java
Repackager repackager = new Repackager(sourceJarFile);
repackager.setBackupSource(false);
repackager.repackage(new Libraries() {
            @Override
            public void doWithLibraries(LibraryCallback callback) throws IOException {
                // Build system specific implementation, callback for each dependency
                // callback.library(new Library(nestedFile, LibraryScope.COMPILE));
            }
        });
```

--------------------------------

### Install Spring Boot CLI with MacPorts

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Install the Spring Boot CLI on macOS using MacPorts.

```bash
$ sudo port install spring-boot-cli

```

--------------------------------

### Check Java Version

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Run this command to verify your Java installation before installing Spring Boot. Requires Java SDK v1.8 or higher.

```bash
$ java -version
```

--------------------------------

### Secure .conf file for init.d service

Source: https://docs.spring.io/spring-boot/docs/2.2.7.RELEASE/reference/htmlsingle

Set permissions to read-only for owner and change ownership to root for the .conf file. This is required when root controls the service and the .conf file customizes startup.

```bash
$ chmod 400 your-app.conf
$ sudo chown root:root your-app.conf
```
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