How to enable HTTP response caching in Spring Boot

Turns out the no-cache HTTP headers are set by Spring Security. This is discussed in http://docs.spring.io/spring-security/site/docs/current/reference/htmlsingle/#headers.

The following disables the HTTP response header Pragma: no-cache, but doesn’t otherwise solve the problem:

import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.config.annotation.web.servlet.configuration.EnableWebMvcSecurity;

@Configuration
@EnableWebMvcSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        // Prevent the HTTP response header of "Pragma: no-cache".
        http.headers().cacheControl().disable();
    }
}

I ended up disabling Spring Security completely for public static resources as following (in the same class as above):

@Override
public void configure(WebSecurity web) throws Exception {
    web.ignoring().antMatchers("/static/public/**");
}

This requires configuring two resource handlers to get cache control headers right:

@Configuration
public class MvcConfigurer extends WebMvcConfigurerAdapter
        implements EmbeddedServletContainerCustomizer {
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        // Resources without Spring Security. No cache control response headers.
        registry.addResourceHandler("/static/public/**")
            .addResourceLocations("classpath:/static/public/");

        // Resources controlled by Spring Security, which
        // adds "Cache-Control: must-revalidate".
        registry.addResourceHandler("/static/**")
            .addResourceLocations("classpath:/static/")
            .setCachePeriod(3600*24);
    }
}

See also Serving static web resources in Spring Boot & Spring Security application.