Datacenter proxies are essentially high-performance HTTP/S proxies allowing you to edit traffic between your application and the internet. They can be used for a variety of reasons, including modifying traffic, debugging issues, security purposes (blocking certain types of requests, obfuscating where your application is hosted), caching content locally etc. This article will focus on different use cases that datacenter proxies are used for.
Preventing accidental disclosure of private information
When working with an API, it's important to make sure that no one outside of your organization/application can access data they shouldn't have access to. At best, this results in unwanted attention from angry users who suddenly find their credit card numbers posted online; at worst it can result in your web application being hacked.
One way of doing this is to create a datacenter proxy that sits between your application and the API you're communicating with. The proxy will then be responsible for making sure that any requests made are safe or sanitized before they reach the API.
This might involve anonymizing/obfuscating certain pieces of information, stripping out some key pieces of information (such as credit card numbers), ensuring data is not cached on the client, etc. If you've developed an API yourself, you could also use this approach to make sure only authenticated users have access to your codebase by placing authentication details within HTTP headers passed through the datacenter proxy.
Another popular use case involving private information is when a third-party API suddenly changes its terms of service/API and can no longer be used without embedding your own authentication mechanism. In this case, the same general approach involving either developing or modifying an existing proxy to add in your own custom business logic for dealing with private information is going to be useful.
Having a datacenter proxy between your application and the internet allows you to inspect traffic at various different points within your infrastructure. This is especially helpful when it comes to debugging network problems that might crop up along with ensuring there aren't any security issues with requests being made from your codebase—especially if these requests are reaching a third-party API which may not always behave as expected.
A common issue that can occur when serving a web application from a single location is that requests may sometimes get blocked or throttled depending on the company providing the service. For example, if your application is hosted on Amazon's Elastic Container Service, you can't have all of Amazon's servers reject requests to your codebase even if some arbitrary piece of user-submitted data causes issues with it.
In this case, adding a datacenter proxy between Amazon ECS and your web application will allow you to see any errors thrown by Amazon's infrastructure and ensure these are handled appropriately within your own infrastructure/application via logging, etc.
In addition to preventing accidental disclosure of private information, as mentioned above, datacenter proxies can be utilized as a tool to prevent cross-site request forgery attacks. This is especially important when an application has no authentication built in and is instead relying on a third-party API to handle this for them.
When a client makes a request via your application to a third-party API, it's possible that the user can make requests without having been authenticated with the third-party service at all, which might allow them to do things they're not meant to be able to execute such as change their password or cancel their payment, etc.
In cases where there is little/no authentication infrastructure built into your codebase, you have two options: either adding extra security yourself or using one of these datacenter proxies. You potentially handle authentication yourself, but this will be time consuming and error prone. The alternative is to use one of these datacenter proxies that does authentication for you, which can then ensure that requests made to this third-party API are by authenticated users only and in the right context (such as a user with the right permissions).
You may want to serve different versions of your web application depending on where in the world users are coming from, i.e., if they're visiting/using your app from within the European Union you might want to add extra functionality such as displaying prices including VAT tax for services offered in Europe.
As far as possible, it's best practice to try and avoid having hard coded rules within your codebase ('views' within Django, controller responses in Rails, etc.) and instead rely on adding this logic into your datacenter proxy. This is because doing so allows you to swap between different proxies depending on the location(s) of your users-for example, if a user comes from Europe, you can switch to an EU-specific proxy which will ensure that prices are displayed as expected.
In summation, datacenter proxies can be used for a variety of reasons and offer lots of benefits when it comes to simplifying your infrastructure and ensuring your web application behaves as expected. Keep the above considerations in mind and you should be well on your way to adding one of these proxies to your infrastructure.