Mastering Flask Web Development - Second Edition

Creating highly available applications that scale

High availability (HA) and scalability is an ever more important subject. It should be taken into consideration from the development phase, all the way up to the release stage. Monolithic architectures, where all the features and services that comprise your application can't be separated or are installed on one single instance, will not resist failure, and won't scale either. Vertical scaling will only go so far, and in case of failure, will increase recovery times, as well as the impact on the user. This is an important and complex subject and, as you may have guessed, there is no single solution to solve it.

To think about HA, we have to be pessimistic. Remember—failure can't be eliminated, ...