The first edition of the Extreme CFD workshop was held in Toulouse at ENSEEIHT from the 17th to the 21st of July, 2017 under the hospices of the SUCCESS scientific group (http://success.coria-cfd.fr). It gathered 25 participants from CERFACS, CORIA, EM2C, IMAG, IMFT, LEGI and SAFRAN TECH grouped in 9 projects. Each project consisted of users and developers of the AVBP and YALES2 CFD tools and their aims were to develop novel models and algorithms, which will exploit large HPC resources, and to tackle new multi-scale problems. During the workshop, D. Saucereau and F. Pecquery presented ArianeGroup CFD challenges and G. Hautreux from GENCI gave a tutorial on hybrid MPI/OpenMP programming for future HPC systems. This fruitful week was concluded by a wrap-up session to give perspectives and feed the AVBP and YALES2 roadmaps. V. Moureau, L. Selle and O. Vermorel, the coordinators, and the participants agreed to organize a second edition next year. The coordinators acknowledge the financial support of the LABEX EMC3 and LEGI, and ENSEEIHT for the accommodations.