The maintenance of software systems is a very important part of a software engineer's role. One thing I have learned is that having only one person responsible for a critical piece of software is risky. That is why I had to take steps to improve the bus factor for the software systems I maintain.

To achieve this, I identified an intern who was interested in learning more about the microservices I developed and maintained. I made it a priority to work alongside him and mentor him as we went about the development and maintenance work. This approach allowed me to transfer my knowledge and expertise to him, while at the same time ensuring that there was someone else who was familiar with the code.

To facilitate this process, I introduced pair programming on working calls. Pair programming usually involves two engineers working together on a single machine, taking turns to write code and review each other's work. This approach helped him to gain hands-on experience in developing and maintaining the microservices while at the same time benefiting from my guidance and mentorship.

In addition to working alongside the intern and introducing pair programming, I took other steps to improve the bus factor. I made sure that the microservices were well-documented, with clear instructions on how to deploy, maintain, and troubleshoot them. We are in the process of creating a comprehensive set of unit tests to ensure that the microservices function correctly and could be updated without causing unintended consequences.

Finally, the stable version of our source code is always open-source. This ensures that I am not the only person with access to the microservices. And I continuously ensure that most members are familiar with how everything works in the codebases I maintain. This means that if I was not available, someone else could take over without too much difficulty.

In conclusion, improving the bus factor of critical pieces of software is crucial for any organization. Working alongside another team member and introducing pair programming can be an effective way to transfer knowledge and expertise, while at the same time improving the bus factor. Documentation and code reviews are also crucial, ensuring that the code is well-documented, and any mistakes are caught early. By adopting these collaborative approaches and sharing the responsibility for the microservices, we can build more resilient software and avoid the risks associated with the bus factor.