Resizing virtual private networks in provider network environments

A system, comprising;

• a virtual private network on a provider network, wherein the virtual private network has an initial IP address space;
• and
• a control plane implemented by one or more devices on the provider network that performs:
• configure one or more additional IP address spaces in the virtual private network;
• assign IP addresses within at least one of the IP address spaces in the virtual private network to resource instances, wherein the resource instances include virtual machines executing on one or more host devices on the provider network;
• receive, via an application programming interface (API), a request that specifies an IP address space to be deleted from the virtual private network on the provider network;
• subsequent to receiving the request that specifies the specified IP address space to be deleted from the virtual private network, check for resource instances with IP addresses within the specified IP address space;
• and
• upon determining that there are no resource instances with IP addresses within the specified IP address space, delete the specified IP address space from the virtual private network.