Gradle: Build 'fat jar' with Spring Boot Dependencies

Question

I am using Gradle to build and package a very simple spring boot application (99% static content) into a jar with embedded tomcat.

I tried creating said jar, at first the result was 86k and did not launch, because it was missing some Spring boot classes. I concluded this jar I made contained none of the application's dependencies, and since I did want a completely self-contained jar, I should do more research.

This is when I discovered the advice to add the from {configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } section to the 'jar' which causes it to pull in all of the dependencies. (I hope). I'm familiar with the idea of the ternary operator and I can see what it's trying to do here.

Unfortunately it is still not working! Here is the error I get on launch, and below is my build.gradle.

I want a spring boot application with embedded tomcat fully contained in a jar. Am I doing something highly unconventional?
Any help at this point would be greatly appreciated.

(About 80 lines of successful Spring Boot launch messages followed immediately by:
18:16:54.890 [main] WARN  o.s.b.c.e.AnnotationConfigEmbeddedWebApplicationContext - Exception encountered during context initialization - cancelling refresh attempt
org.springframework.context.ApplicationContextException: Unable to start embedded container; nested exception is org.springframework.context.ApplicationContextException: Unable to start EmbeddedWebApplicationContext due to missing EmbeddedServletContainerFactory bean.
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:132) [SpringWsTest1.jar:na]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:474) ~[SpringWsTest1.jar:na]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:117) [SpringWsTest1.jar:na]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:689) [SpringWsTest1.jar:na]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:321) [SpringWsTest1.jar:na]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:969) [SpringWsTest1.jar:na]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:958) [SpringWsTest1.jar:na]
    at ws.Application.main(Application.java:11) [SpringWsTest1.jar:na]
Caused by: org.springframework.context.ApplicationContextException: Unable to start EmbeddedWebApplicationContext due to missing EmbeddedServletContainerFactory bean.
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.getEmbeddedServletContainerFactory(EmbeddedWebApplicationContext.java:182) [SpringWsTest1.jar:na]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.createEmbeddedServletContainer(EmbeddedWebApplicationContext.java:155) [SpringWsTest1.jar:na]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:129) [SpringWsTest1.jar:na]
    ... 7 common frames omitted
18:16:54.891 [main] DEBUG o.s.b.f.s.DefaultListableBeanFactory - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@3b084709: defining beans [org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,application,org.springframework.context.annotation.ConfigurationClassPostProcessor.importAwareProcessor,org.springframework.context.annotation.ConfigurationClassPostProcessor.enhancedConfigurationProcessor,demoController,greetingController,org.springframework.boot.autoconfigure.AutoConfigurationPackages]; root of factory hierarchy
18:16:54.891 [main] ERROR o.s.boot.SpringApplication - Application startup failed
org.springframework.context.ApplicationContextException: Unable to start embedded container; nested exception is org.springframework.context.ApplicationContextException: Unable to start EmbeddedWebApplicationContext due to missing EmbeddedServletContainerFactory bean.
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:132) ~[SpringWsTest1.jar:na]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:474) ~[SpringWsTest1.jar:na]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:117) ~[SpringWsTest1.jar:na]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:689) [SpringWsTest1.jar:na]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:321) [SpringWsTest1.jar:na]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:969) [SpringWsTest1.jar:na]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:958) [SpringWsTest1.jar:na]
    at ws.Application.main(Application.java:11) [SpringWsTest1.jar:na]
Caused by: org.springframework.context.ApplicationContextException: Unable to start EmbeddedWebApplicationContext due to missing EmbeddedServletContainerFactory bean.
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.getEmbeddedServletContainerFactory(EmbeddedWebApplicationContext.java:182) ~[SpringWsTest1.jar:na]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.createEmbeddedServletContainer(EmbeddedWebApplicationContext.java:155) ~[SpringWsTest1.jar:na]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:129) ~[SpringWsTest1.jar:na]
    ... 7 common frames omitted
Exception in thread "main" org.springframework.context.ApplicationContextException: Unable to start embedded container; nested exception is org.springframework.context.ApplicationContextException: Unable to start EmbeddedWebApplicationContext due to missing EmbeddedServletContainerFactory bean.
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:132)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:474)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:117)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:689)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:321)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:969)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:958)
    at ws.Application.main(Application.java:11)
Caused by: org.springframework.context.ApplicationContextException: Unable to start EmbeddedWebApplicationContext due to missing EmbeddedServletContainerFactory bean.
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.getEmbeddedServletContainerFactory(EmbeddedWebApplicationContext.java:182)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.createEmbeddedServletContainer(EmbeddedWebApplicationContext.java:155)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:129)
    ... 7 more

build.gradle I am using:

println System.getProperty("java.home")

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:1.2.7.RELEASE")
    }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'idea'
apply plugin: 'spring-boot'


jar {
    manifest {
        attributes 'Main-Class': 'ws.Application'
    }

    from {
        configurations.compile.collect { it.isDirectory() ? it : zipTree(it) }
    }
}


repositories {
    mavenCentral()
}


dependencies {
    compile("org.springframework.boot:spring-boot-starter-web")
    testCompile("junit:junit")
}

task wrapper(type: Wrapper) {
    gradleVersion = '2.3'
}

sourceCompatibility = 1.8
targetCompatibility = 1.8

Answer 1

With current versions of gradle, add this at the top of your build.gradle file:

plugins {
    id "org.springframework.boot" version "2.0.0.RELEASE"
}

then just gradle build - you don't need to do anything more.

See this plugin's homepage to find the latest version.