The log of a twelve-factor app should be treated as an event stream. In a traditional environment, the log can be generated for a file. However, problems can arise, such as a lack of disk space. We know that in a cloud computing environment, where there is elastic scalability depending on demand, processes are born and die all the time. Likewise, machines and containers may no longer be used. Log files could get lost in this resizing in the cloud. Treating a log as an event stream is critical on a platform such as a cloud. In this way, logs can be directed anywhere. For example, they could be directed to a database in NoSQL, to another service, to a file in a repository, to a log-indexing-and-analysis system, or to a data-warehousing system.