Spring Boot application works as standalone but class not found when deployed in Tomcat

Question

I have spring boot application , a microservice

I can run it without any problem as Spring boot application

mvn clean compile spring-boot:run

Now if I try to deploy it in tomcat 9, am getting ClassNotFoundException, shows as if am missing some jar I tried adding the missing jar for one application , but it keeps coming for newer applications. There are no steps involved in here, compile ,test as standadlone, then package and deploy to tomcat.

What could be the issue. I guess the actual log is not needed here as the problem seems to be very generic

Answer 1

The Answer is simple, plain and stupid. If you face any similar issue, just make sure , you are running a similar version of tomcat.

My spring boot application worked fine, when ran using mvn spring-boot:run but my actual tomcat server was bit older, so it was missing few libraries.

Upgrading the tomcat version fixed it

Answer 2

First of all, Spring boot doesn't require a container, You can execute using java -jar yourspsringboot.war

In your pom, Are you compiling it as war with dependencies? If so, verify that under WEB-INF/lib directory. If you not able to find the dependencies in lib directory then it should be the issue.

Answer 3

Please include following build tag in your pom. Create new build a deploy. It will work. I also faced this issue.

<build>
        <plugins>
            <plugin>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.1.0</version>
                <configuration>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>1.5.3.RELEASE</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.20</version>
                <configuration>
                    <useSystemClassLoader>false</useSystemClassLoader>
                </configuration>
            </plugin>
        </plugins>
    </build>