What actions are triggered by reserving a CIDR range in IPAM?

[serottez]

Hi, I am wondering what exactly the IPAM application does when a user reserves a CIDR range? From my understanding, IPAM only has read permissions on Azure resources (excluding the Azure resources that were deployed by IPAM). So, when a user reserves a CIDR range in IPAM, does IPAM only add a record to the Cosmos DB database, or does a reservation trigger other actions/updates, too? Thank you!

[DCMattyG]

Hi @serottez, when a Reservation is created it does indeed update the data within CosmosDB. After creating a Reservation, you will be provided with an ID which you will need to apply as a Tag on the new Virtual Network you create within Azure using the provided CIDR so that the Azure IPAM tool will know which Virtual Network to associate with the Reservation and fulfill it.

[georgegil]

This can certainly do with being documented better imho.

Took me a bit to work it out

[DCMattyG]

I 100% concur with you @georgegil, and my apologies.

I am indeed working on some highly-improved documentation around this process which should be ready shortly.

[serottez]

Thank you @DCMattyG. Is the CosmosDB record the only modification made when a CIDR range is reserved? I am considering implementing this in a preexisting and mature Azure environment, where multiple end users will have permission to make CIDR reservations. I want to make sure that reservations made by these users do not have domino effects on other Azure resources. Thank you!

[DCMattyG]

Indeed you are good @serottez. This solution was designed for multiple users to share and perform exactly the process you outlined.

And as always, Azure IPAM will never modify any Azure resources as it only has Reader permissions to the Root Management Group.