A great tool for the right job
Use Cases and Deployment Scope
Azure Functions are the first step in the server-less offering on Azure. They are a tool in the Azure Solution Architect toolbox, and they come handy whenever you have to execute a small-medium amount of logic in a broader cloud-native process, or as a minimal, cost-effective backend, for example for a mostly static website.
Pros
- They natively integrate with many triggers from other Azure services, like Blob Storage or Event Grid, which is super handy when creating cloud-native applications on Azure (data wrangling pipelines, business process automation, data ingestion for IoT, ...)
- They natively support many common languages and frameworks, which makes them easily approachable by teams with a diverse background
- They are cheap solutions for low-usage or "seasonal" applications that exhibits a recurring usage/non-usage pattern (batch processing, montly reports, ...)
Cons
- My biggest complaint is that they promote a development model that tightly couples the infrastructure with the app logic. This can be fine in many scenarios, but it can take some time to build the right abstractions if you want to decouple you application from this deployment model. This is true at least using .NET functions.
- In some points, they "leak" their abstraction and - from what I understood - they're actually based on the App Service/Web App "WebJob SDK" infrastructure. This makes sense, since they also share some legacy behavior from their ancestor.
- For larger projects, their mixing of logic, code and infrastructure can become difficult to manage. In these situations, good App Services or brand new Container Apps could be a better fit.
Return on Investment
- They allowed me to create solutions with low TCO for the customer, which loves the result and the low price, that helped me create solutions for more clients in less time.
- You can save up to 100% of your compute bill, if you stay under a certain tenant conditions.
Alternatives Considered
Azure App Service, Azure Container Apps, Azure Container Instances and Azure Kubernetes Service (AKS)