Personal go links

By Ian Fisher, 6 October 2020

If you've ever set foot in an office building in Silicon Valley, you may have noticed that the noticeboards, placards, cafe menus and occasionally even construction signs were plastered with a certain type of cryptic missive: go/food, you might have seen, or go/hr, perhaps even go/home. These ubiquitous strings are neither exclamations nor directives but in fact a highly useful kind of shortened URL: go/food could stand for https://whatever.com/menu, for instance, or go/hr could be https://fizzbuzz.corp.com/human-resources. Anyone inside the company can create a new go link with the name and URL of their choosing, and everything from meeting notes to slide decks to API docs have their own go links. You can type go links directly into the address bar of your browser, and they are highlighted automatically in commit descriptions, chat messages, bug comments, and the like.

I found go links to be useful enough at work that I wrote my own go links service for my personal computer. I have go/weather pointed at Dark Sky and go/air at the EPA's Air Quality Index page for my city. go/python/xyz points to the Python standard library docs: go/python/re takes me to the documentation for the re package, go/python/http takes me to the http docs, and so on. I use another prefix, gh/, to go to my GitHub repositories: gh/blog brings up the source code for my blog. The latter two kinds of links are especially useful because you could not feasibly make bookmarks for all the modules in the Python standard library, or all of your GitHub repositories.

The code

The code for the go links service is very straightforward. It intercepts HTTP requests for go links using a Firefox extension, and sends them to a local server that looks up the link destination and sends an HTTP redirect back to the browser.

Here's the Firefox extension. It uses the webRequest API to intercept and redirect HTTP requests:

function redirect(request) {
  const prefix = 'http://go/';
  const path = request.url.slice(prefix.length);
  return { redirectUrl: 'http://localhost:5000/go/' + path };
}

browser.webRequest.onBeforeRequest.addListener(redirect, { urls: ['http://go/*']}, ['blocking']);

If you use Chrome rather than Firefox, change browser.webRequest in the last line to chrome.webRequest.

And here's the server code. It uses Flask for convenience, but the standard library http module would also work:

from flask import Flask, redirect

app = Flask(__name__)

LINKS = {
    "iafisher": "https://iafisher.com",
}

@app.route("/go/<path:path>")
def go(path):
    return redirect(LINKS[path])

If you have Flask installed, you can start the server with export FLASK_APP=goserver.py; python3 -m flask run, assuming the code is in a file called goserver.py.

Installing the browser extension

To install the browser extension, create a file called manifest.json with the following contents:

{
  "manifest_version": 2,
  "name": "GoLinks",
  "version": "0.1",
  "description": "Redirects http://go/ links to localhost:5000",
  "background": {
    "scripts": [
      "redirect.js"
    ]
  },
  "permissions": ["webRequest", "webRequestBlocking", "<all_urls>"]
}

Put the JavaScript code from above in a file called redirect.js alongside the manifest file.

On Firefox

You can now install the extension on Firefox temporarily following these instructions. Unfortunately, Mozilla won't let you install the extension permanently without signing it on their servers. To do so, you will first need to create API credentials.

Once you have your API credentials, create a .secrets file outside¹ of the directory that holds redirect.js and manifest.json with:

export WEB_EXT_API_KEY=<your key here>
export WEB_EXT_API_SECRET=<your secret here>

Don't track this file in git, since it contains your secret key.

Finally, you'll need to use Mozilla's web-ext command-line tool to build and sign the extension. Install it with npm install -g web-ext and, inside the directory with your files, run:

web-ext build -o
source ../.secrets
web-ext sign

web-ext sign will take quite a while. When it's finished, you will have an .xpi file in a new web-ext-artifacts directory, which you can then install permanently from the about:addons page using the "Install Add-on From File" option. Note that each time you sign the extension, you'll need to bump the version number in the manifest.

Firefox tends to interpret go links as search queries rather than URLs, which bypasses the extension entirely and sends them straight to the search engine. You can fix this by going to about:config in Firefox and adding a new browser.fixup.domainwhitelist.go boolean setting, set to true. Or you can set browser.fixup.dns_first_for_single_words, in case you want to use multiple prefixes or a different one than go/.²

On Chrome

On Chrome, enter chrome://extensions in your address bar, turn on developer mode, click on "Load unpacked", and select the directory containing manifest.json. Your extension will remain installed even after you close the browser.

Alternative approaches

You may wonder, is the local server even necessary? Why can't you just put the LINKS map in the extension and directly redirect requests that way?

The answer is, you could, but you would have to reload your extension every time you added a new link. Since, as we've seen, re-installing the extension takes some time, this wouldn't be practical unless you rarely or never add new links.

If you are hell-bent on avoiding a local server, you could try using the persistent storage API to store the links in the extension, but that likely won't work, either. The problem is that the storage.get method is asynchronous, but the redirect function must be synchronous to be able to redirect the request. MDN claims that the onBeforeRequest callback can return a Promise, but I've found that you can't redirect the request with a Promise, and Promises might not work at all in Chrome.

Another way you could do it is by setting go as an alias to an IP address of your choosing in your computer's hosts.txt. This would require you to either bind your local server to port 80 or spin up a server on the public Internet, but it would obviate the need for a browser extension.

Prior art

golinks.io sells go links as a managed service. It's ostensibly free for individual users, but you need a company email address to sign up (i.e., not a Gmail address). You can manage links through a web interface, track the number of visits to each link, and control access to individual links, among other things.

According to a Medium post published by golinks.io, the go link was created at North Carolina State University in 2009, although their implementation (as of 2020) uses a dedicated go.nscu.edu/ subdomain rather than the more concise go/ domain.³

Go links were introduced to Google by Benjamin Staffin, and former Googlers spread them across the tech industry.

I found a couple of other personal go links projects on GitHub. Kelly Norton's version is the most similar to mine. James Mills's implementation works by overriding the browser's default search engine, so you can enter whatever into your address bar instead of go/whatever. This is similar to Facebook's internal system. Adam Yi's version is a GCP project that binds to a custom domain, like at NCSU. ∎