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Details in Strangler Fig pattern - Azure Architecture Center | Microsoft Learn |
Problem
Need to incrementally migrate a legacy system to a new service in the cloud and so, gradually.
Run 2 separate systems or versions of an app means that clients have to know where particular features are located.
Need to minimize the risk from the migration of app and data.
Solution
Create a façade that intercepts requests going to the backend legacy system. The façade routes these requests either to the legacy application or the new services.
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Strangler In Practice
Option A : Using Azure Application Gateway.
The facade is a reverse proxy and not cesseraly a forward proxy : we can use Azure Application Gateway or Azure Service Fabric Reverse Proxy.
We need to have multiple instances of the same service or multiple versions of the same service if we wish to use Azure Application Gateway (Gateway Routing Pattern)
Option B : Creating the strangler Fig in code.
The other option would be in the code only : we set up our routes, pointing to 2 different clusters (being our apps - modern and legacy).
Create to code related to the read of the routes
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