fzzf: Customizing log URLs on Gerrit comments was natively supported in Zuul in the past (at least that's what the developers told me), but this was changed to hard coded build URLs from the Zuul Web dashboard. This can however be circumvented by overwriting the zuul.log_url variable [1] (not to be confused with zuul_log_url [2], which is a role variable from zuul-jobs). All keys within the zuul dictionary are special variables that control some internal mechanisms of Zuul. If you inspect the upload-logs role, for example, you'll notice it executes a task to return the log URL to Zuul using this special variable. [3]

[1] https://zuul-ci.org/docs/zuul/latest/job-content.html#returning-the-log-url
[2] https://zuul-ci.org/docs/zuul-jobs/log-roles.html#rolevar-upload-logs.zuul_log_url
[3] https://opendev.org/zuul/zuul-jobs/src/commit/21faa1a9d8661a8dac3740ef9e05b1067b7bbffc/roles/upload-logs/tasks/main.yaml#L78-L84