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Closes https://github.com/coder/internal/issues/312 Depends on https://github.com/coder/terraform-provider-coder/pull/408 This PR adds support for defining an **autoscaling block** for prebuilds, allowing number of desired instances to scale dynamically based on a schedule. Example usage: ``` data "coder_workspace_preset" "us-nix" { ... prebuilds = { instances = 0 # default to 0 instances scheduling = { timezone = "UTC" # a single timezone is used for simplicity # Scale to 3 instances during the work week schedule { cron = "* 8-18 * * 1-5" # from 8AM–6:59PM, Mon–Fri, UTC instances = 3 # scale to 3 instances } # Scale to 1 instance on Saturdays for urgent support queries schedule { cron = "* 8-14 * * 6" # from 8AM–2:59PM, Sat, UTC instances = 1 # scale to 1 instance } } } } ``` ### Behavior - Multiple `schedule` blocks per `prebuilds` block are supported. - If the current time matches any defined autoscaling schedule, the corresponding number of instances is used. - If no schedule matches, the **default instance count** (`prebuilds.instances`) is used as a fallback. ### Why This feature allows prebuild instance capacity to adapt to predictable usage patterns, such as: - Scaling up during business hours or high-demand periods - Reducing capacity during off-hours to save resources ### Cron specification The cron specification is interpreted as a **continuous time range.** For example, the expression: ``` * 9-18 * * 1-5 ``` is intended to represent a continuous range from **09:00 to 18:59**, Monday through Friday. However, due to minor implementation imprecision, it is currently interpreted as a range from **08:59:00 to 18:58:59**, Monday through Friday. This slight discrepancy arises because the evaluation is based on whether a specific **point in time** falls within the range, using the `github.com/coder/coder/v2/coderd/schedule/cron` library, which performs per-minute matching rather than strict range evaluation. --------- Co-authored-by: Danny Kopping <danny@coder.com>