A while back I was asking about using asset hashes in filenames to help bust CDN caches. For now, I...

# ktor

[Carter]

A while back I was asking about using asset hashes in filenames to help bust CDN caches. For now, I’m avoiding generating the hashes at build time, instead generating them dynamically at runtime. I prototyped something that works.

This works, but uses deprecated resource API:

Assets.entries.forEach {
    resource(
        it.hashedPath, // asset/js/browser-app-af00f73c8693fe418e83b020c04d3e78324a1e7dc5a0dd3784de87f66d9ebf68.js
        it.defaultPath // asset/js/browser-app.js
    )
}

This does not work, using staticResources.

Assets.entries.forEach {
    staticResources(
        it.hashedPath, // asset/js/browser-app-af00f73c8693fe418e83b020c04d3e78324a1e7dc5a0dd3784de87f66d9ebf68.js
        it.basePackage // asset/js
    ) {
        default(it.defaultPath) // asset/js/browser-app.js
    }
}

Is there a way to do this better with the staticResources or another Ktor API?

[Aleksei Tirman [JB]]

You can replace the deprecated code with the following one:

Assets.entries.forEach { entry ->
    get(entry.hashedPath) {
        val resource = call.resolveResource(entry.defaultPath)
        if (resource != null) call.respond(resource)
    }
}

[Carter]

Works like a charm, thank you! Finding resolveResource was the challenge!

[Carter]

Is there any existing Ktor issue for generating hashes for assets?

If there’s not, I might soon file an issue since my solution works for now but has some limitations that a built-in solution might be able to handle better. At least it could articulate the use case for the team to consider this functionality in the future.

[Aleksei Tirman [JB]]

I cannot find such feature request.

[Carter]

I got around to filing this on YouTrack: https://youtrack.jetbrains.com/issue/KTOR-6717/Hashing-of-Asset-Paths-for-Improved-Caching