Swagger springdoc-openapi-ui doesn't work when SpringBoot run in JAR

Question

Swagger-UI works generally fine when I run SpringBoot application directly in the IDE (by clicking run on main class) or via maven spring-boot:run plugin. Anyway it's broken when I run SpringBoot as JAR file trough java -jar command in CLI.

How the app is built (modules):

1. root (no parent):

   a. core (no parent)

   b. rest-api (root as parent)

   • • spring boot 2.7.7 as BOM dependency
   • • main SpringBoot class
   • • spring security (JWT token)
   • • dependency to core

rest-api -> pom.xml fragment:

    <dependencies>
                <!-- MORE dependencies -->
    
        <dependency>
            <groupId>org.springdoc</groupId>
            <artifactId>springdoc-openapi-ui</artifactId>
            <version>1.6.14</version>
        </dependency>
        
        <dependency>
            <groupId>org.springdoc</groupId>
            <artifactId>springdoc-openapi-security</artifactId>
            <version>1.6.14</version>
        </dependency>
        
    </dependencies>
    
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.7.7</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.7.5</version>
                <configuration>
                    <mainClass>example.package.MainBootApplication</mainClass>
                    <skip>false</skip>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>3.4.2</version>
                <configuration>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                    <archive>
                        <manifest>
                            <mainClass>example.package.MainBootApplication</mainClass>
                        </manifest>
                    </archive>
                </configuration>
                <executions>
                    <execution>
                        <id>make-assembly</id>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

main app class:

package example.package;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import io.swagger.v3.oas.annotations.OpenAPIDefinition;

@OpenAPIDefinition
@SpringBootApplication
public class MainBootApplication {

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

}

I tested following URLs:

a) http://localhost:8080/swagger-ui/index.html?configUrl=/v3/api-docs/swagger-config (works when it run with maven)

b) http://localhost:8080/swagger-ui/index.html (works when it run with maven)

c) http://localhost:8080/swagger-ui.html

I build my app with mvn clean package command and it assembled a JAR with all dependencies (see rest-api/pom.xml content) and later java -jar /path/to/file.jar . The application works fine and I can call my REST end-points properly but Swagger-UI is broken. When I run app trough main class with IDE Swagger works fine.

I can see a log info when the app starts directly trough IDE that SpringDoc initializes properly (after I call the URL) .

[2m2022-12-30 13:03:39.722[0;39m [32m INFO[0;39m [35m23776[0;39m [2m---[0;39m [2m[nio-8080-exec-8][0;39m [36mo.springdoc.api.AbstractOpenApiResource [0;39m [2m:[0;39m Init duration for springdoc-openapi is: 330 ms

This log doesn't appear when I run trough JAR file:

Any ideas?

Answer 1

I solved it by replacing maven-assembly-plugin with spring-boot-maven-plugin like below:

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>2.7.5</version>
                <configuration>
                    <mainClass>example.package.MainBootApplication</mainClass>
                    <skip>false</skip>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                        <configuration>
                            <classifier>jar-with-dependencies</classifier>
                            <mainClass>example.package.MainBootApplication</mainClass>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

maybe it will help someone :-)