S3 Resource handler addResourceLocations error with Spring Framework 6.2.19+

[dafriz]

Type: Bug

Component:
S3

Describe the bug
Using Spring Cloud AWS 3.4.2 when updating from Spring Framework 6.2.18 to 6.2.19 the following no longer works for io.awspring.cloud.s3.S3Resource

@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("path/**")
                .addResourceLocations("s3://bucket/path/")
)

As Spring Framework enforces a slash on end ( spring-projects/spring-framework@fb0c78a )

resolveResourceLocations() was patched to call assertResourceLocation() for every resolved resource — so string-based locations get the same validation. s3:// location encounters problem: Spring Cloud AWS's Location.resolveObjectName() strips the trailing slash ("path/" → "path"), so S3Resource.getURL() builds a path-style URL https://s3.amazonaws.com/path without a trailing slash, and url.getPath() fails the assertion.

[mbecker6]

A workaround until fixed:
I created a wrapper for S3Resource, that delegates to S3Resource and retains the trailing slash.

internal class S3LocationResource(
    private val delegate: S3Resource,
    private val originalLocation: String,
) : AbstractResource() {

    override fun getURL(): URL {
        val base = delegate.getURL()
        return if (originalLocation.endsWith("/")) {
            val str = base.toExternalForm()
            if (str.endsWith("/")) base else URI.create("$str/").toURL()
        } else {
            base
        }
    }

    override fun createRelative(relativePath: String): S3LocationResource =
        S3LocationResource(delegate.createRelative(relativePath), originalLocation + relativePath)

    override fun getDescription(): String = delegate.getDescription()

    override fun getInputStream(): InputStream = delegate.getInputStream()

    override fun exists(): Boolean = delegate.exists()

    override fun getFilename(): String = delegate.getFilename()

    override fun isReadable(): Boolean = delegate.isReadable()

    override fun lastModified(): Long = delegate.lastModified()
}

and registered in our config. We have a :classpath location for the resource as well. if you only have a singular s3 location, I think you could aslo just @ConditionalOnBean with S3Resource.

@Bean
fun myResourceWebHandler(
   s3Client: ObjectProvider<S3Client>,
   s3OutputStreamProvider: ObjectProvider<S3OutputStreamProvider>,
): ResourceWebHandler {
    val s3Location = "s://yourS3path"
    val s3ClientBean = s3Client.getIfAvailable()
    val s3ProviderBean = s3OutputStreamProvider.getIfAvailable()
    val locations = buildList {
        add(ClassPathResource(":classpath:/classpathLocation".removePrefix("classpath:")))
        if (s3Location.startsWith("s3://") && s3ClientBean != null && s3ProviderBean != null) {
            add(S3LocationResource(S3Resource(s3Location, s3ClientBean, s3ProviderBean), s3Location))
        }
    }
    return ResourceWebHandler().apply {
        setLocations(locations)
        setResourceResolvers(
            listOf(
                PathResourceResolver(),
            )
        )
    }
}

@Bean
fun resourceHandlerMapping(myResourceWebHandler: ResourceWebHandler): SimpleUrlHandlerMapping =
    SimpleUrlHandlerMapping(mapOf("/path/**" to myResourceWebHandler), Ordered.LOWEST_PRECEDENCE - 1)

[MatejNedic]

Hey @mbecker6 ,

Thanks on report. Will be fixed as part of 4.1.0 release