Automated allocation using spare IP addresses pools

Techniques and solutions are provided for performing automated allocation of Internet Protocol (IP) addresses. For example, automated allocation of IP addresses can be performed by determining that remaining IP addresses in an available IP address pool are below a threshold value, obtaining a range of contiguous IP addresses from a common spare IP address pool, and allocating the range of contiguous IP addresses from the common spare IP address pool to the available IP address pool. The available IP address pool can then be used to allocate IP addresses to instances and/or services.