Azure Function API Versioning - How to structure my code?

Question

I have created a demo microservices application implemented with the help of Azure Function Apps. For separation of concerns, I have created an API Layer, Business Layer, and a Data Layer.

The API layer, being the function app, calls the business layer which implements the business logic while the data layer implements logic for storing and retrieving data.

After considerable thought, I have decided to use query-based API versioning for my demo.

The question I have is,

What is the best way to organize my code to facilitate this? Is there any other way to organize my code to accommodate the different versions apart from using different namespaces / repos?

As of now, I've created separate namespaces for each version but this has created a lot of code duplication. Also after getting it reviewed by some of my friends, they raised the concern that If separate namespaces are being used I would be forcing legacy systems to change references to the new namespace if they need to update which is not recommended.

Any help would be appreciated.

Ketan · Accepted Answer · 2019-02-25 09:47:31Z

8

The simplest way to implement versioning in Azure Functions is using endpoints. The HttpTrigger Attribute allows the definition of a custom route where you can set the expected version.

// Version 1 of get users
[FunctionName(nameof(V1UserList))]
public static IEnumerable<UserModel> V1UserList(
[HttpTrigger(AuthorizationLevel.Function, "get", Route = "v1/users")]HttpRequest req, ILogger log)
{
}

// Version 2 of get users
[FunctionName(nameof(V2UserList))]
public static IEnumerable<UserModel> V2UserList(
[HttpTrigger(AuthorizationLevel.Function, "get", Route = "v2/users")]HttpRequest req, ILogger log)
{
}

When deploying each version in isolation a router component is required to redirect requests to the correct API endpoint.

The router component can be implemented in Azure using different services, such as:

Azure Function Proxies : you can specify endpoints on your function app that are implemented by another resource. You can use these proxies to break a large API into multiple function apps (as in a microservice architecture), while still presenting a single API surface for clients.
API Management :Azure API Management supports importing Azure Function Apps as new APIs or appending them to existing APIs. The process automatically generates a host key in the Azure Function App, which is then assigned to a named value in Azure API Management.

Sample code for Versioning APIs in Azure Functions

answered Feb 25, 2019 at 9:47

Ketan

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1 Comment

bytedev Over a year ago

FYI this answer is largely take from here: medium.com/@fbeltrao/…

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