I think ... - Cloudflare KVhttps://blog.kmonsoor.com/2021-06-06T00:00:00+06:00Create a free go-link server “on edge” using Cloudflare Worker KV2021-06-06T00:00:00+06:002021-06-06T00:00:00+06:00Khaled Monsoortag:blog.kmonsoor.com,2021-06-06:/golink-server-using-cloudflare-worker-kv/<p>Among quite a few ways to implement a go-link server (i.e., url-forwarder, short-url server, etc.), I will show how to use free-tier Cloudflare Worker (&amp; <span class="caps">KV</span>) to create an in-house, on-edge, <strong>no-webserver</strong> go-link&nbsp;server.</p><p>Among quite a few ways to implement a go-link server (i.e., url-forwarder, short-url server, etc.), I&rsquo;m going to show you how to use free-tier Cloudflare Worker (&amp; <span class="caps">KV</span>) to create an in-house, on-edge, <strong>no-webserver</strong> go-link&nbsp;server.</p> <p>For example, the short-link for this article is <a href="https://go.kmonsoor.com/golink-kv">go.kmonsoor.com/golink-kv</a> </p> <p><img alt="overall structure" src="https://i.imgur.com/MjIS5gD.png"></p> <ul> <li><code>/latest</code> (by which I mean <code>go.yourdomain.co/latest</code>) may point to <code>https://www.yourcompany.com/about/news</code> which is a public&nbsp;page</li> <li><code>/hr-help</code> may point to <code>https://www.company-internal.com/long-link/hr/contact.html</code>, which is company&rsquo;s internal human-resources help&nbsp;portal</li> <li><code>/cnypromo</code> may point to <code>https://shop.yourcompany.com/sales/promotions/?marketing-promo=2021-cny</code> which is a temporary sales promotions page targeting the shoppers during the Chinese new year of&nbsp;2021.</li> </ul> <p>Please note that using the setup and the code below, it&rsquo;ll be possible to resolve short-links via a <strong>single</strong> sub-domain, e.g., <code>go.your-domain.co</code>. However, it&rsquo;s possible (with some modification of the code) to resolve/redirect via <em>any number of domains</em> (your own, of course) towards any other public or private <span class="caps">URL</span>, and all sorts of novelties. However, for brevity&rsquo;s sake, I will discuss the first one, a single sub-domain&nbsp;usecase.</p> <p>To set up a go-link server or short-<span class="caps">URL</span> resolver via a proper <span class="caps">KV</span>+Worker combination, we&rsquo;ll go through these&nbsp;steps:</p> <div class="toc"> <ul> <li><a href="#pre-requisites">Pre-requisites</a></li> <li><a href="#create-the-short-link-map-as-a-kv">Create the short-link map as a <span class="caps">KV</span></a></li> <li><a href="#mapping-a-kv-to-a-worker-variable">Mapping a <span class="caps">KV</span> to a Worker&nbsp;variable</a></li> <li><a href="#handling-a-route-with-webworker">Handling a route with&nbsp;webworker</a></li> <li><a href="#create-the-worker">Create the&nbsp;Worker</a></li> <li><a href="#pointing-a-dns-record-to-the-worker">Pointing a <span class="caps">DNS</span> record to the&nbsp;Worker</a></li> <li><a href="#next-step">Next&nbsp;step</a></li> <li><a href="#related">Related</a></li> </ul> </div> <h1 id="pre-requisites">Pre-requisites<a class="headerlink" href="#pre-requisites" title="Permanent link">&para;</a></h1> <ul> <li>The <span class="caps">DNS</span> resolver for the <strong>root</strong> domain (in the example below, <em><code>kmonsoor.com</code></em>) needs to be Cloudflare. Because the core of the solution, the &ldquo;worker&rdquo;, runs on the nearest (from the user) edge of Cloudflare using a standard <span class="caps">KV</span> (&ldquo;key, value&rdquo;)&nbsp;list.</li> <li>Write permission to the <span class="caps">DNS</span> configuration as you&rsquo;d need to add a new <span class="caps">AAAA</span> <span class="caps">DNS</span>&nbsp;record.</li> <li>Some knowledge of Javascript(<code>ES6</code>), as we are going to write the &ldquo;worker&rdquo; in that&nbsp;language.</li> </ul> <h1 id="create-the-short-link-map-as-a-kv">Create the short-link map as a <span class="caps">KV</span><a class="headerlink" href="#create-the-short-link-map-as-a-kv" title="Permanent link">&para;</a></h1> <p>We&rsquo;ll start the setup by creating the short-link map, the list between the short-link segments that you (or someone in your org) define, and the actual URLs they need to point&nbsp;to.</p> <p>Find the <span class="caps">KV</span> stuff in the <code>Workers</code> section. From the screenshot, please ignore the &ldquo;Route&rdquo; section for&nbsp;now. </p> <p><img alt="Find the KV stuff in the Workers section" src="https://i.imgur.com/b2Rk45u.png"></p> <ul> <li>you&rsquo;d need to create a Worker <span class="caps">KV</span> &ldquo;Namespace&rdquo;. Name the namespace as you seem fit. I named it <code>REDIRECTS</code> (in all caps just as a convention, not&nbsp;required). </li> <li>List the short links <span class="amp">&amp;</span> their respective target URLs. From the examples in the intro, the keys <code>latest</code>, <code>hr-help</code>, <code>cnypromo</code> etc. would be in as the &ldquo;key&rdquo;, and the target full links as the respective&nbsp;&ldquo;value&rdquo;.</li> <li>Remember <span class="caps">NOT</span> to start the short part with &lsquo;/&rsquo;. It&rsquo;ll be taken care of in the&nbsp;code.</li> </ul> <p><img alt="Create the short-link map as a KV" src="https://i.imgur.com/jkC8bSr.png"></p> <p>Once you&rsquo;ve listed all your desired (short-link, target-link) combinations, now we have a <span class="caps">KV</span> on Cloudflare. However, it&rsquo;s not referencable from your Worker code, not yet. Hence the next&nbsp;step.</p> <h1 id="mapping-a-kv-to-a-worker-variable">Mapping a <span class="caps">KV</span> to a Worker variable<a class="headerlink" href="#mapping-a-kv-to-a-worker-variable" title="Permanent link">&para;</a></h1> <p>Now, we will map the previously created <span class="caps">KV</span> to a variable that can be referenced from our Worker code. Please note that though I used different names, it can be the same as well. Also, note that multiple Workers can access a single <span class="caps">KV</span>, and vice versa is also true; a single Worker can reference multiple&nbsp;KVs.</p> <p><img alt="Mapping a KV to a Worker variable" src="https://i.imgur.com/lb7G9si.png"></p> <h1 id="handling-a-route-with-webworker">Handling a route with webworker<a class="headerlink" href="#handling-a-route-with-webworker" title="Permanent link">&para;</a></h1> <p><img alt="Handling a route with webworker" src="https://i.imgur.com/KohHRfR.png"></p> <h1 id="create-the-worker">Create the Worker<a class="headerlink" href="#create-the-worker" title="Permanent link">&para;</a></h1> <p>Now, we will write Worker-code that runs on <code>V8</code> runtime on the nearest (from the requesting user) &ldquo;edge&rdquo; location of Cloudflare, to execute the code and deliver the result(s) to the user. In this case, that would be to redirect user-requested address to the mapped one (by you, in the <span class="caps">KV</span> namespace&nbsp;above).</p> <p><img alt="Creating a worker" src="https://i.imgur.com/eNfZNyN.png"></p> <p>The code editor looks like&nbsp;this: </p> <p><img alt="The code editor for Cloudflare worker" src="https://i.imgur.com/pb9AE9v.png"></p> <p>If you rather prefer to copy-paste, please feel free to do it from the below GitHub&nbsp;Gist.</p> <div class="gist"> <script src="https://gist.github.com/kmonsoor/dc9f96660423c96471f8574ba018d867.js"></script> </div> <p>Once done, it should look like &hellip; <img alt="created webworker" src="https://i.imgur.com/XSdKB56.png"></p> <h1 id="pointing-a-dns-record-to-the-worker">Pointing a <span class="caps">DNS</span> record to the Worker<a class="headerlink" href="#pointing-a-dns-record-to-the-worker" title="Permanent link">&para;</a></h1> <p>Finally, we need to point a <span class="caps">DNS</span> record that&rsquo;ll redirect all requests to your re-soutign sub-domain (e.g. <code>go.your-domain.com</code>) to the Cloudflare Worker that we just&nbsp;created.</p> <p>According to the Cloudflare docs, the <span class="caps">DNNS</span> record must be an <span class="caps">AAAA</span> record, pointing to the IPv6 address <code>100::</code>. The &ldquo;Name&rdquo; here is the &ldquo;sub-domain&rdquo; part of your choice, which is better be short, to rightfully serve our goal&nbsp;here. </p> <p><img alt="Pointing a DNS record to it" src="https://i.imgur.com/62bk7pe.png"></p> <p>Voila ! Now, test some of the short-urls that you&rsquo;ve mapped via the <span class="caps">KV</span>. Enjoy ! Watch out for the target usage though. <a href="https://developers.cloudflare.com/workers/platform/limits#worker-limits">Here&rsquo;s the limit</a>. </p> <p>I think you&rsquo;ll be fine, unless you&rsquo;re some celebrity&nbsp;;)</p> <h1 id="next-step">Next step<a class="headerlink" href="#next-step" title="Permanent link">&para;</a></h1> <p>As the next step, I&rsquo;m thinking to create a generic <code>Go/Link</code> resolver browser extension. Then, someone can set their own default domain or company domain of choice as short-domain host. In that case, entering just <code>go/hr-help</code> on the browser will take to <code>https://www.company-internal.com/.../hr/contact.html</code> that we have discussed at the beginning (remember the example case of an internal human resources help&nbsp;portal?).</p> <h1 id="related">Related<a class="headerlink" href="#related" title="Permanent link">&para;</a></h1> <p>If you want to do this url-direction <strong>on your server, but only using webserver</strong>, try this: <a href="https://blog.kmonsoor.com/personal-shortlink-server-using-Caddy/">Personal short-link server using only&nbsp;Caddyserver</a></p> <hr> <p>If you find this post helpful, you can show your support <a href="https://www.patreon.com/kmonsoor">through Patreon</a> or by <a href="https://ko-fi.com/kmonsoor">buying me a coffee</a>. <em>Thanks!</em></p>