Spanish ATLAS Tier-1 & Tier-2 perspective on computing over the next years

Since the beginning of the WLCG Project the Spanish ATLAS computing centers have participated with reliable and stable resources as well as personnel for the ATLAS Collaboration. Our contribution to the ATLAS Tier2s and Tier1s computing resources (disk and CPUs) in the last 10 years has been around 4-5%. In 2016 an international advisory committee recommended to revise our contribution according to the participation in the ATLAS experiment. With this scenario, we are optimizing the federation of three sites located in Barcelona, Madrid and Valencia, considering that the ATLAS collaboration has developed workflows and tools to flexibly use all the resources available to the collaboration, where the tiered structure is somehow vanishing. In this contribution, we would like to show the evolution and technical updates in the ATLAS Spanish Federated Tier2 and Tier1. Some developments we are involved in, like the Event Index project, as well as the use of opportunistic resources will be useful to reach our goal. We discuss the foreseen/proposed scenario towards a sustainable computing environment for the Spanish ATLAS community in the HL-LHC period