Effortlessly Renew API Tokens in ASP.NET 6.0
Situation: your ASP.NET project needs to interact with an external API, and that API requires each request to have an access token, but that access token expires after a set amount of time. How do you ensure that you always have an access token ready without requesting a new one each time you instantiate your client?
ASP.NET 6.0 introduced PeriodicTimer for when you need a timer for doing all those asynchronous operations. Utilizing this timer with the existing BackgroundService and some handy-dandy dependency injection gives us the tools we need to make asynchronous calls to external APIs in the background of our ASP.NET application simple.
Client Interface and Implementation
Let’s start with a basic client interface and implementation. Note that on the implementation below, we have a static property for the access token. That’s going to come in handy for when we need to update the access token.
Background Service and Timer
Next, we’ll create a class for our background service. We inject the HttpClient and configure it, as well as the form content we’ll need to make our request. Modify these to meet your specific needs. We’ll also expose a property to set the token duration in seconds, so we can appropriately fire off the renewal before the existing token expires.
Wire Up Dependency Injection
All we need to do now is wire this up in our start up class, and let ASP.NET do the rest of the heavy lifting for us!
Can It BE Any More Simple?
This solution is easy to modify to suit your needs. You can inject any other objects, including configurations using the IOptions<> pattern, as long as you add the configuration before registering the hosted service (line 11), otherwise it will not be resolved.
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The example above also makes use the FluentHttpClient library — of which I am both author and maintainer, so this is a shameless plug — which adds extensions to make it easier and more readable to make calls using the built-in HttpClient. Check it out and start using it today!
