将 Fastly 配置迁移到 CloudFlare Workers答案

【问题标题】：Move Fastly config to CloudFlare Workers将 Fastly 配置迁移到 CloudFlare Workers
【发布时间】：2018-09-27 16:20:24
【问题描述】：

如何重写以下代码以使用 CF Workers 功能？

# Start 
if(req.url ~ "^/app" ) { 
set req.url = regsub(req.url, "^/app/", "/"); 
set req.http.X-DR-SUBDIR = "app"; 
} 
#end condition

【问题讨论】：

标签： cloudflare cloudflare-workers

【解决方案1】：

Cloudflare Workers 实现了 Service Worker 标准，因此您需要根据 Service Worker 重新实现您发布的 VCL 代码 sn-p。

在我向您展示如何做到这一点之前，请考虑当https://example.com/apple 的请求到达代理时会发生什么。我希望^/app 的第一个正则表达式匹配，但^/app/ 的第二个正则表达式不匹配 - 即，请求将在不更改 URL 的情况下通过，但添加了 X-DR-SUBDIR: app标题。

我怀疑这种行为是一个错误，所以我将首先实现一个 worker，就好像第一个正则表达式是 ^/app/。

addEventListener("fetch", event => {
  let request = event.request

  // Unlike VCL's req.url, request.url is an absolute URL string,
  // so we need to parse it to find the start of the path. We'll
  // need it as a separate object in order to mutate it, as well.
  let url = new URL(request.url)

  if (url.pathname.startsWith("/app/")) {
    // Rewrite the URL and set the X-DR-SUBDIR header.

    url.pathname = url.pathname.slice("/app".length)

    // Copying the request with `new Request()` serves two purposes:
    //   1. It is the only way to actually change the request's URL.
    //   2. It makes `request.headers` mutable. (The headers property
    //      on the original `event.request` is always immutable, meaning
    //      our call to `request.headers.set()` below would throw.)
    request = new Request(url, request)

    request.headers.set("X-DR-SUBDIR", "app")
  }

  event.respondWith(fetch(request))
})

要重温https://example.com/apple 的案例，如果我们真的想要一个迂腐再现 VCL sn-p 行为的 Cloudflare Worker，我们可以更改这些行（省略 cmets）：

  if (url.pathname.startsWith("/app/")) {
    url.pathname = url.pathname.slice("/app".length)
    // ...
  }

对这些：

  if (url.pathname.startsWith("/app")) {
    if (url.pathname.startsWith("/app/")) {
      url.pathname = url.pathname.slice("/app".length)
    }
    // ...
  }

【讨论】：