Azure Virtual Network now supports updates without subnet property
Azure API supports the HTTP methods PUT, GET, DELETE for the CRUD (Create/Retrieve/Update/Delete) operations on your resources. The PUT operation is used for both Create and Update. For existing resources, using a PUT with the existing resources preserves them and adds any new resources supplied in the JSON. If any of the existing resources are omitted from the JSON for the PUT operation, those resources are removed from the Azure deployment.
Based on customer support cases and feedback, we observed that this behavior causes problems for customers while performing updates to existing deployments. This is a challenge in the case of subnets in the VNet where any updates to the virtual network, or addition of resources (e.g. adding a routing table), to a virtual network require you to supply the entire virtual network configuration in addition to the subnets. To make it easier for customers, we have implemented a change in the PUT API behavior for virtual network updates. This change allows you to skip the subnet specification in a PUT call without deleting the existing subnets. This capability is now available in a Limited Preview in all the EUAP regions, US West Central and US North with API version 2023-09-01.
Previous behavior
The existing behavior has been to expect a subnet property in the PUT virtual network call. If a subnet property isn't included, the subnets are deleted. This might not be the intention.
New PUT VNet behavior
Assuming your existing configuration is as follows:
|
"subnets": [ { "name": "SubnetA", "properties": {...} }, { "name": "SubnetB", "properties": {...} }, { "name": "SubnetC", "properties": {...} }, { "name": "SubnetD", "properties": {...} }
] |
The updated behavior is as follows:
- If a PUT virtual network doesn't include a subnet property, no changes to the existing set of subnets is made.
- If subnet property is explicitly marked as empty, we will treat this as a request to delete all the existing subnets. For example:
|
"subnets": [] |
OR
|
"subnets": null |
- If a subnet property is supplied with specific values as follows:
|
"subnets": [ { "name": "SubnetA", "properties": {...} }, { "name": "Subnet-B", "properties": {...} }, { "name": "Subnet-X", "properties": {...} } ] |
In this case, the following changes are made to the virtual network:
- SubnetA is unchanged. Assuming the supplied configuration is the same as existing.
- SubnetB, SubnetC and SubnetD are deleted.
- Two new subnets Subnet-B and Subnet-X are created with the new configuration.
This behavior remains unchanged from what Azure currently has today.
Next Steps
Test the new behavior in the regions listed above and share your feedback.
Published on:
Learn moreRelated posts
Introducing Markers in Azure Maps for Power BI
We’re announcing a powerful new capability in the Azure Maps Visual for Power BI: Markers. This feature makes it easier than ever for organiza...
Azure Boards additional field filters (private preview)
We’re introducing a limited private preview that allows you to add additional fields as filters on backlog and Kanban boards. This long-reques...
What’s new with Azure Repos?
We thought it was a good time to check in and highlight some of the work happening in Azure Repos. In this post, we’ve covered several recent ...
Part 1: Building Your First Serverless HTTP API on Azure with Azure Functions & FastAPI
Introduction This post is Part 1 of the series Serverless Application Development with Azure Functions and Azure Cosmos DB, where we explore ...
Announcing GPT 5.2 Availability in Azure for U.S. Government Secret and Top Secret Clouds
Today, we are excited to announce that GPT-5.2, Azure OpenAI’s newest frontier reasoning model, is available in Microsoft Azure for U.S. Gover...