Spring Boot with JSF; Could not find backup for factory javax.faces.context.FacesContextFactory

I'm having some problems with Spring Boot and JSF. The servlet appears to start up correctly, but when I attempt to access a resource I get the following exception

java.lang.IllegalStateException: Could not find backup for factory javax.faces.context.FacesContextFactory. 
    at javax.faces.FactoryFinder$FactoryManager.getFactory(FactoryFinder.java:1011)
    at javax.faces.FactoryFinder.getFactory(FactoryFinder.java:343)
    at javax.faces.webapp.FacesServlet.init(FacesServlet.java:302)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284)
    at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:884)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:134)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
    at org.apache.catalina.valves.RemoteIpValve.invoke(RemoteIpValve.java:683)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1720)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1679)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:724)

My Application class is as follows

@Configuration
@EnableAutoConfiguration
@ComponentScan
public class Application extends SpringBootServletInitializer {

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

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
    }

    @Bean
    public FacesServlet facesServlet() {
        return new FacesServlet();
    }

    @Bean
    public ServletRegistrationBean facesServletRegistration() {
        ServletRegistrationBean registration = new ServletRegistrationBean(
            facesServlet(), "*.xhtml");
        registration.setName("Christmas");
        return registration;
    }

    @Bean
    public ServletListenerRegistrationBean<ConfigureListener> jsfConfigureListener() {
        return new ServletListenerRegistrationBean<ConfigureListener>(
            new ConfigureListener());
    }
}

I have no web.xml or faces-config.xml, and my pom.xml is as follows

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.x.y.z</groupId>
    <artifactId>project</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.1.5.RELEASE</version>
    </parent>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

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

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.primefaces</groupId>
            <artifactId>primefaces</artifactId>
            <version>5.0</version>
        </dependency>

        <!-- JSF 2 -->
        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-api</artifactId>
            <version>2.1.11</version>
        </dependency>

        <dependency>
            <groupId>com.sun.faces</groupId>
            <artifactId>jsf-impl</artifactId>
            <version>2.1.11</version>
        </dependency>
    </dependencies>

</project>

I have a suspicion that there are some conflicts in the dependencies relating to the jsf api, but I can't seem to figure out where. Any help on fixing this issue would be greatly appreciated.

Solution

To get JSF working on Spring Boot without a web.xml or faces-config.xml you need to force it to load its configuration files via an init parameter on the ServletContext. An easy way to do that is to implement ServletContextAware:

public class Application implements ServletContextAware {

    // ...

    @Override
    public void setServletContext(ServletContext servletContext) {
        servletContext.setInitParameter("com.sun.faces.forceLoadConfiguration", Boolean.TRUE.toString());           
    }
}

JSF's ConfigureListener also has a dependency on JSP, so you'll need to add a dependency on Jasper to your pom:

<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-jasper</artifactId>
</dependency>

It's not directly related to your problem, but you don't need to declare FacesServlet as a bean. The ServletRegistrationBean is sufficient.

This leaves Application.java looking as follows:

import javax.faces.webapp.FacesServlet;
import javax.servlet.ServletContext;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.context.embedded.ServletListenerRegistrationBean;
import org.springframework.boot.context.embedded.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.context.ServletContextAware;

import com.sun.faces.config.ConfigureListener;

@Configuration
@EnableAutoConfiguration
@ComponentScan
public class Application implements ServletContextAware {

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

    @Bean
    public ServletRegistrationBean facesServletRegistration() {
        ServletRegistrationBean registration = new ServletRegistrationBean(
            new FacesServlet(), "*.xhtml");
        registration.setLoadOnStartup(1);
        return registration;
    }

    @Bean
    public ServletListenerRegistrationBean<ConfigureListener> jsfConfigureListener() {
        return new ServletListenerRegistrationBean<ConfigureListener>(
            new ConfigureListener());
    }

    @Override
    public void setServletContext(ServletContext servletContext) {
        servletContext.setInitParameter("com.sun.faces.forceLoadConfiguration", Boolean.TRUE.toString());       
    }
}