At FANDOM we believe our applications should be resilient, that is they should be able to recover from failures and while the failure occurs still be useful for the users. Health checks are one of the ways to make applications self-healing.
The idea is that the health checks detect when an instance of the application reaches an invalid state. A supervisor monitors those health checks and attempts to fix any issues. Depending on your platform the action might be different.
Many frameworks (like Dropwizard and Spring) and platforms (like Kubernetes and Marathon) encourage you to implement health checks for your web applications.
When a health check fails, AWS will stop sending requests to that instance. That’s pretty straightforward — we suspec…Read more >
As the GDPR deadline has come and past, our team has reflected on its efforts of building the front-end library. The task was to build a front-end modal which FANDOM would integrate across its web products. For obvious reasons (a $20 million fine), we set a strict zero tolerance level for any failures. Our goal from the outset was to create the most well tested piece of code at FANDOM.
The first problem we had to tackle was being able to reliably detect where in the world the user currently viewing a given page is visiting from. Our network provider Fastly provides a Geo Detection service through its Varnish servers. This exposes a wealth of information, but most importantly, an ISO 3166-2 country code associated with the client IP address.…
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