Hello Guix! Here is a second update on my GSoC project after the first month.
As a reminder, Hydra (https://nixos.org/hydra/) is a Nix-based continuous build system which is used by Guix to compile packages on different platforms and to distribute packages substitutes. The aim of this project is to replace Hydra with a more integrated software written in Guile, named “Cuirass”. After providing a first basic evaluation loop described in my previous mail, I have started thinking about the architecture of the global job evaluation/compilation process in order to identify what type of data structures would make sense. It was not easy for me to reason about the different layers of current Hydra usage in Guix, so it took me 2 weeks to analyse it and provide a first decomposition of logic steps. For now this decomposition is: job-spec > job > build-result where: - 'job-spec' defines all the information required by Cuirass to get the actual job definitions. These information contains the repository type and url, the file and procedure name which yields a list of job, and the list of arguments passed to that procedure. - 'job' contains the derivation file name which describe all the dependencies. - 'build-result' contains the output obtained when realizing/building the derivation from a job + some logs. 'job-spec' and 'job' are already implemented in Cuirass. However 'build-result' will require a database to be useful. Since I have no experience with databases at all, this last week has been dedicated to learn more about them, play with SQL queries, and use Guile-dbi and Guile-sqlite3 bindings. My plan is to use Sqlite first and eventually switch to Postgresql later when concurrent writers would be critical. The next step is to apply my newly acquired knowledge by allowing 'build-result' entries to be added to the database. I will be AFK for 5 days so I will start working on that, next Sunday. For those willing to follow my work, a Git repository is available here: https://notabug.org/mthl/cuirass Everyone is of course welcome to provide any feedback. Thanks. -- Mathieu Lirzin
