Implementing API policies

1. Implementing API policies

Welcome back! In this video, we'll tackle a common developer challenge: securing, transforming, and controlling access to APIs without rewriting backend code for every new requirement. The answer lies in APIM Policies.

2. Introduction to API policies

Policies in APIM are like putting a bouncer at the door and speed-limit signs on the road for your APIs. They check who’s allowed in, block trouble, and throttle heavy traffic so one user can’t overwhelm the system. Anything that goes in and out of API Gateway is controlled by policies.

3. API Management policies overview

Policies are a set of powerful rules you write in simple XML. Think of them as a request-and-response pipeline. You can insert rules at different stages to shape traffic, and the best part is, you don't have to touch your backend code at all.

4. Example: backward compatibility

For example, a new version of our API may require additional information that the older versions of a mobile app don't provide. If we still want to support the older versions, we may want to add the missing information via API policies before it reaches the backend.

5. Policy scopes

We can have global policies to enforce organization-wide standards, like a security rule that applies to everything. We can have policies at the API level to manage versioning for a specific product. Or we can configure policies on individual operations, giving us fine-grained control, like caching only the 'GET products' endpoint.

6. Inbound policies

When a request arrives from a client, APIM evaluates inbound policies first. For example, we can make requests coming from old versions of an app compatible with the new version of API by augmenting the payload data. Let's say, a malicious user tries to steal data. Inbound policies can guard against such attempts by detecting a malformed request or missing data. This early guardrail prevents bad data from ever touching our services.

7. Security and throttling

Inbound policies are also responsible for security. One of the most common security policies is to validate a JWT, or JSON Web Token. Think of a JWT as a digital ID card sent by the client with their request. The validate-jwt policy acts as a bouncer, checking that the ID card is legitimate, hasn't expired, and was issued by a trusted source like Entra ID. For more stringent control, rate‑limiting and quota policies let us throttle excessive clients, ensuring fair usage and protecting our backend from overload.

8. Outbound policies

After passing through to the backend, outbound policies allow us to massage responses before those are returned. Imagine a restaurant. Customer places an order (like an app making a request). That order goes to the kitchen (the backend), where the food is prepared. But before the dish is sent back to the customer, it passes through a final plating station — this is where a chef might: Remove anything the customer doesn’t want (like a food allergy warning, or in tech terms, sensitive headers), Add a label like “Keep Refrigerated” (caching directive), Or change the presentation — like turning a bowl of soup into a smoothie (converting XML to JSON). These ensure that the dish is exactly how the customer expects it, even though it was cooked a certain way in the back.

9. Let's practice!

Let's practice by applying the policies!

Create Your Free Account

By continuing, you accept our Terms of Use, our Privacy Policy and that your data is stored in the USA.