Abstract
Scalability and maintainability challenges in monolithic systems have led to
the adoption of microservices, which divide systems into smaller, independent
services. However, migrating existing monolithic systems to microservices is a
complex and resource-intensive task, which can benefit from machine learning
(ML) to automate some of its phases. Choosing the right ML approach for
migration remains challenging for practitioners. Previous works studied
separately the objectives, artifacts, techniques, tools, and benefits and
challenges of migrating monolithic systems to microservices. No work has yet
investigated systematically existing ML approaches for this migration to
understand the \revised{automated migration phases}, inputs used, ML techniques
applied, evaluation processes followed, and challenges encountered. We present
a systematic literature review (SLR) that aggregates, synthesises, and
discusses the approaches and results of 81 primary studies (PSs) published
between 2015 and 2024. We followed the Preferred Reporting Items for Systematic
Review and Meta-Analysis (PRISMA) statement to report our findings and answer
our research questions (RQs). We extract and analyse data from these PSs to
answer our RQs. We synthesise the findings in the form of a classification that
shows the usage of ML techniques in migrating monolithic systems to
microservices. The findings reveal that some phases of the migration process,
such as monitoring and service identification, are well-studied, while others,
like packaging microservices, remain unexplored. Additionally, the findings
highlight key challenges, including limited data availability, scalability and
complexity constraints, insufficient tool support, and the absence of
standardized benchmarking, emphasizing the need for more holistic solutions.