  Context: DevOps has become one of the fastest growing software development
paradigms in the industry. However, this trend has presented the challenge of
ensuring secure software delivery while maintaining the agility of DevOps. The
requirement of secure outputs in DevOps led to the DevSecOps paradigm, which is
gaining the interest of both the industry and academia. However, the adoption
of DevSecOps in practice has been challenging.
  Objective: This study aims to identify the challenges faced by practitioners
when adopting DevSecOps and the solutions proposed by peer-reviewed studies. We
intend our study to aid practitioners planning to adopt DevSecOps, foresee
problems and decide on solutions early. We also aim to find specific gap areas
for future research and development.
  Method: We have conducted a Systematic Literature Review of 52 peer-reviewed
studies. The thematic analysis method was applied to analyze the extracted
data.
  Results: We identified 21 challenges related to adopting DevSecOps, 31
specific solutions, and key gap areas in this domain. The results were
classified into four themes: People, Practices, Tools, and Infrastructure. Our
findings show that tools-related challenges and solutions were the most
frequently reported, driven by the need for automation in this paradigm.
Shift-left security and continuous security assessment were two key practices
recommended for DevSecOps. People-related factors were considered critical for
adoption success but less studied.
  Conclusions: We highlight the need for developer-centered application
security testing tools that target the continuous practices in DevOps. More
work is needed on how traditionally manual security practices can be automated
to suit the rapid deployment cycles. Finally, achieving a suitable balance
between the speed of delivery and security is a significant issue practitioners
face in this paradigm.
