Vapor 3 Middleware to serve files from the public folder and respect Cache-Control headers

FileMiddlewareWithCache.swift

import Vapor

/// Services files from the public folder.
public final class FileMiddlewareWithCache: Middleware, Service {
    /// The public directory.
    /// note: does _not_ end with a slash
    let publicDirectory: String

    public var webTypes = [MediaType]()

    enum CacheControl: String {
        case css, js
        case svg, jpg, jpeg, gif, png, webp

        var maxAge: UInt {
            switch self {
            case .css, .js: return 31_536_000 // 1 year (must use versioning)
            case .svg, .jpg, .jpeg, .gif, .png, .webp: return // 1 year (must use versioning)
            }
        }

    }

    /// Creates a new filemiddleware.
    public init(publicDirectory: String) {
        self.publicDirectory = publicDirectory.hasSuffix("/") ? publicDirectory : publicDirectory + "/"
    }

    /// See Middleware.respond.
    public func respond(to req: Request, chainingTo next: Responder) throws -> Future<Response> {
        var path = req.http.url.path
        if path.hasPrefix("/") {
            path = String(path.dropFirst())
        }
        guard !path.contains("../") else {
            throw Abort(.forbidden)
        }

        let filePath = self.publicDirectory + path

        var isDir: ObjCBool = false
        guard FileManager.default.fileExists(atPath: filePath, isDirectory: &isDir) else {
            return try next.respond(to: req)
        }

        guard !isDir.boolValue else {
            return try next.respond(to: req)
        }

        if let ext = filePath.components(separatedBy: ".").last,
            let cacheControlForExt = CacheControl(rawValue: ext) {
            return try req.streamFile(at: filePath)
                .map(to: Response.self) { res in
                    res.http.headers.replaceOrAdd(name: HTTPHeaderName.cacheControl, value: "max-age=\(cacheControlForExt.maxAge)")
                    return res
            }
        } else {
            return try req.streamFile(at: filePath)
        }
    }
}

Hi, I am Derek. I am new to Vapor 3. I have two questions about using FileMiddleware.

1. Can I create a directory in Pubic folder when receiving a POST request through FileMiddleware?

2. Is there a way to get the Public folder path when Vapor app is running? Because I expected I could use this path and FileManager to create directory in Public folder.

Please excuse me to bother you with above questions. I came across this gist post when I was searching the way to create directory in Public folder. Hope there is a hint for me to achieve that.