This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Boot 3.3.4! |
This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Boot 3.3.4! |
Spring Boot supports traditional deployment as well as more modern forms of deployment. This section answers common questions about traditional deployment.
Create a Deployable War File
Because Spring WebFlux does not strictly depend on the servlet API and applications are deployed by default on an embedded Reactor Netty server, War deployment is not supported for WebFlux applications. |
The first step in producing a deployable war file is to provide a SpringBootServletInitializer
subclass and override its configure
method.
Doing so makes use of Spring Framework’s servlet 3.0 support and lets you configure your application when it is launched by the servlet container.
Typically, you should update your application’s main class to extend SpringBootServletInitializer
, as shown in the following example:
-
Java
-
Kotlin
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
@SpringBootApplication
public class MyApplication extends SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(MyApplication.class);
}
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
}
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.builder.SpringApplicationBuilder
import org.springframework.boot.runApplication
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer
@SpringBootApplication
class MyApplication : SpringBootServletInitializer() {
override fun configure(application: SpringApplicationBuilder): SpringApplicationBuilder {
return application.sources(MyApplication::class.java)
}
}
fun main(args: Array<String>) {
runApplication<MyApplication>(*args)
}
The next step is to update your build configuration such that your project produces a war file rather than a jar file.
If you use Maven and spring-boot-starter-parent
(which configures Maven’s war plugin for you), all you need to do is to modify pom.xml
to change the packaging to war, as follows:
<packaging>war</packaging>
If you use Gradle, you need to modify build.gradle
to apply the war plugin to the project, as follows:
apply plugin: 'war'
The final step in the process is to ensure that the embedded servlet container does not interfere with the servlet container to which the war file is deployed. To do so, you need to mark the embedded servlet container dependency as being provided.
If you use Maven, the following example marks the servlet container (Tomcat, in this case) as being provided:
<dependencies>
<!-- ... -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
<!-- ... -->
</dependencies>
If you use Gradle, the following example marks the servlet container (Tomcat, in this case) as being provided:
dependencies {
// ...
providedRuntime 'org.springframework.boot:spring-boot-starter-tomcat'
// ...
}
providedRuntime is preferred to Gradle’s compileOnly configuration.
Among other limitations, compileOnly dependencies are not on the test classpath, so any web-based integration tests fail.
|
If you use the Spring Boot Build Tool Plugins, marking the embedded servlet container dependency as provided produces an executable war file with the provided dependencies packaged in a lib-provided
directory.
This means that, in addition to being deployable to a servlet container, you can also run your application by using java -jar
on the command line.
Because Spring WebFlux does not strictly depend on the servlet API and applications are deployed by default on an embedded Reactor Netty server, War deployment is not supported for WebFlux applications. |
providedRuntime is preferred to Gradle’s compileOnly configuration.
Among other limitations, compileOnly dependencies are not on the test classpath, so any web-based integration tests fail.
|
Convert an Existing Application to Spring Boot
To convert an existing non-web Spring application to a Spring Boot application, replace the code that creates your ApplicationContext
and replace it with calls to SpringApplication
or SpringApplicationBuilder
.
Spring MVC web applications are generally amenable to first creating a deployable war application and then migrating it later to an executable war or jar.
See the Getting Started Guide on Converting a jar to a war.
To create a deployable war by extending SpringBootServletInitializer
(for example, in a class called Application
) and adding the Spring Boot @SpringBootApplication
annotation, use code similar to that shown in the following example:
-
Java
-
Kotlin
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
@SpringBootApplication
public class MyApplication extends SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
// Customize the application or call application.sources(...) to add sources
// Since our example is itself a @Configuration class (through
// @SpringBootApplication)
// we actually do not need to override this method.
return application;
}
}
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.builder.SpringApplicationBuilder
import org.springframework.boot.runApplication
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer
@SpringBootApplication
class MyApplication : SpringBootServletInitializer() {
override fun configure(application: SpringApplicationBuilder): SpringApplicationBuilder {
// Customize the application or call application.sources(...) to add sources
// Since our example is itself a @Configuration class (through @SpringBootApplication)
// we actually do not need to override this method.
return application
}
}
Remember that, whatever you put in the sources
is merely a Spring ApplicationContext
.
Normally, anything that already works should work here.
There might be some beans you can remove later and let Spring Boot provide its own defaults for them, but it should be possible to get something working before you need to do that.
Static resources can be moved to /public
(or /static
or /resources
or /META-INF/resources
) in the classpath root.
The same applies to messages.properties
(which Spring Boot automatically detects in the root of the classpath).
Vanilla usage of Spring DispatcherServlet
and Spring Security should require no further changes.
If you have other features in your application (for instance, using other servlets or filters), you may need to add some configuration to your Application
context, by replacing those elements from the web.xml
, as follows:
-
A
@Bean
of typeServlet
orServletRegistrationBean
installs that bean in the container as if it were a<servlet/>
and<servlet-mapping/>
inweb.xml
. -
A
@Bean
of typeFilter
orFilterRegistrationBean
behaves similarly (as a<filter/>
and<filter-mapping/>
). -
An
ApplicationContext
in an XML file can be added through an@ImportResource
in yourApplication
. Alternatively, cases where annotation configuration is heavily used already can be recreated in a few lines as@Bean
definitions.
Once the war file is working, you can make it executable by adding a main
method to your Application
, as shown in the following example:
-
Java
-
Kotlin
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
fun main(args: Array<String>) {
runApplication<MyApplication>(*args)
}
If you intend to start your application as a war or as an executable application, you need to share the customizations of the builder in a method that is both available to the
|
Applications can fall into more than one category:
-
Servlet 3.0+ applications with no
web.xml
. -
Applications with a
web.xml
. -
Applications with a context hierarchy.
-
Applications without a context hierarchy.
All of these should be amenable to translation, but each might require slightly different techniques.
Servlet 3.0+ applications might translate pretty easily if they already use the Spring Servlet 3.0+ initializer support classes.
Normally, all the code from an existing WebApplicationInitializer
can be moved into a SpringBootServletInitializer
.
If your existing application has more than one ApplicationContext
(for example, if it uses AbstractDispatcherServletInitializer
) then you might be able to combine all your context sources into a single SpringApplication
.
The main complication you might encounter is if combining does not work and you need to maintain the context hierarchy.
See the entry on building a hierarchy for examples.
An existing parent context that contains web-specific features usually needs to be broken up so that all the ServletContextAware
components are in the child context.
Applications that are not already Spring applications might be convertible to Spring Boot applications, and the previously mentioned guidance may help.
However, you may yet encounter problems.
In that case, we suggest asking questions on Stack Overflow with a tag of spring-boot
.
If you intend to start your application as a war or as an executable application, you need to share the customizations of the builder in a method that is both available to the
|
Deploying a WAR to WebLogic
To deploy a Spring Boot application to WebLogic, you must ensure that your servlet initializer directly implements WebApplicationInitializer
(even if you extend from a base class that already implements it).
A typical initializer for WebLogic should resemble the following example:
-
Java
-
Kotlin
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
import org.springframework.web.WebApplicationInitializer;
@SpringBootApplication
public class MyApplication extends SpringBootServletInitializer implements WebApplicationInitializer {
}
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer
import org.springframework.web.WebApplicationInitializer
@SpringBootApplication
class MyApplication : SpringBootServletInitializer(), WebApplicationInitializer
If you use Logback, you also need to tell WebLogic to prefer the packaged version rather than the version that was pre-installed with the server.
You can do so by adding a WEB-INF/weblogic.xml
file with the following contents:
<?xml version="1.0" encoding="UTF-8"?>
<wls:weblogic-web-app
xmlns:wls="http://xmlns.oracle.com/weblogic/weblogic-web-app"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
https://java.sun.com/xml/ns/javaee/ejb-jar_3_0.xsd
http://xmlns.oracle.com/weblogic/weblogic-web-app
https://xmlns.oracle.com/weblogic/weblogic-web-app/1.4/weblogic-web-app.xsd">
<wls:container-descriptor>
<wls:prefer-application-packages>
<wls:package-name>org.slf4j</wls:package-name>
</wls:prefer-application-packages>
</wls:container-descriptor>
</wls:weblogic-web-app>