Goalie - A go short-link service implementation

This is an implementation of go/ links that makes it simple to access internal web assets and share them on a coorporate network.

Goalie was initially developed by Anton Friberg together with Oscar Svensson both part time student employees at [Axis Communications]. The backend is written in Python using a Flask framework called Eve and stores the shortcuts in a mongoDB database. The frontend utilizes React.js and Redux to make it easy to edit shortcuts. The entire application is deployed using Docker.

Background

go/ links is a service that is believed to have originated at Google according to this blog post and this github repo. The idea is that people on the coorporate network can easily navigate between internal services by directing their browser to http://go/service-name.

For example, if we want to be redirected towards information of our internal git repo we visit http://go/git.

These days it is common to see similar services at many large IT companies.

Notable Features

• Easily create and modify shortcuts for web URLs.
• LDAP/AD authentication.
• Immediate availability of shortcuts to all employees.
• Shortcuts are viewable and searchable by all employees.
• Only an administrator or the owner of the shortcut is able to modify or delete it.

As we have been using this service it has proven to be useful on multiple occasions, for example:

• To avoid having to remember complicated URLs such as team meeting slides, documentation pages, important resources and internal services.
• Making it easier to share scattered web resources with new colleagues.
• As a searchable index of available internal web resources.
• As a DNS service for testing environments.

Advanced Features

It may not be apparent at first glance but the pattern field for a new shortcut actually accepts a regex value. This provides the service with many additional features. We will provide a brief overview by presenting some examples.

Single target for multiple patterns

This allows both go/git and go/gerrit to direct the user to the internal git resource without the need for multiple shortcut entries.

Pattern	Target
(git|gerrit)	https://git.example.com

Match multiple forms of spelling

This pattern matches color-code-search, colour-code-search, color-code and colour-code.

Pattern	Target
colou?r-code(-search)?	https://color.example.com

Capture groups inserted into target

This example in particular is very interesting. The first entry allow users to enter go/git/search_string in the web browser and be redirected to a search for search_string on the internal git website. The second entry allows go/git/303492/1 which points to the first patch set of the git commit with the id 303492.

Pattern	Target
git/(.+)	https://git.example.com/q/\1
git/(\d+)(/\d+)?	https://git.example.com/q/\1\2

Wildcards

Some readers probably realize that the regex features are easy to abuse. On inserts we only check for uniqueness i.e. that the pattern is not already used by another shortcut. We do actually allow wildcard patterns like this:

Pattern	Target
(.+)	https://www.google.com/search?q=\1

This would potentially clash with all other shortcuts and to handle cases such as this we rank shortcuts and try to find the most specific one to redirect the visitor towards.

Ranking

If multiple patterns match the incomming URL string the most specific pattern that matches should be returned. Currently this ranking looks like the following. Taking the acronym atf as an exampel.

Rank	Target
1.	atf
2.	(atf)
3.	at\w
4.	at.
5.	at.?
6.	at[a-z]
7.	(a|atf|a-test-framework)
8.	(atf)(.*)
9.	at.+
10.	.+
11.	.*

This ranking might not be perfect since at[a-z] at number 6 is probably considered more specific than at. by many users.

Contributers & Maintainers

Maintainer

• Anton Friberg

Contributers

• Anton Friberg
• Oscar Svensson