unicorn['worker_processes'] has been deprecated since 13.10 and was removed in 14.0. Starting with GitLab 14.0, Unicorn is no longer supported and users must switch to Puma, following https://docs.gitlab .com/ee/administration/operations/puma.html. - 明春网
GitLab 12.9のUnicornをPumaに変更する - Qiita
How we reduced 502 errors by caring about PID 1 in Kubernetes | GitLab
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Integrating your Rails project with GitLab review apps | kyrofa's blog