- Created and maintained automatically by Coder to match your specified preset configurations.

- Claimed transparently when developers create workspaces.

- Monitored and replaced automatically to maintain your desired pool size.

- Automatically scaled based on time-based schedules to optimize resource usage.

Expired prebuilt workspaces are removed during the reconciliation loop to avoid stale environments and resource waste.

New prebuilt workspaces are only created to maintain the desired count if needed.

Prebuilt workspaces support time-based scheduling to scale the number of instances based on usage patterns.

This allows you to reduce resource costs during off-hours while maintaining availability during peak usage times.

Configure scheduling by adding a`scheduling` block within your`prebuilds` configuration:

**Scheduling configuration:**

-**`timezone`**: The timezone for all cron expressions (required). Only a single timezone is supported per scheduling configuration.

-**`schedule`**: One or more schedule blocks defining when to scale to specific instance counts.

-**`cron`**: Cron expression interpreted as continuous time ranges (required).

-**`instances`**: Number of prebuilt workspaces to maintain during this schedule (required).

**How scheduling works:**

1. Coder evaluates all active schedules at regular intervals.

2. The schedule that matches the current time becomes active. Overlapping schedules are disallowed by validation rules.

3. If no schedules match the current time, the base`instances` count is used.

4. The reconciliation loop automatically creates or destroys prebuilt workspaces to match the target count.

**Cron expression format:**

Cron expressions follow the format:`* HOUR DOM MONTH DAY-OF-WEEK`

-`*` (minute): Must always be`*` to ensure the schedule covers entire hours rather than specific minute intervals

-`HOUR`: 0-23, range (e.g., 8-18 for 8AM-6:59PM), or`*`

-`DOM` (day-of-month): 1-31, range, or`*`

-`MONTH`: 1-12, range, or`*`

-`DAY-OF-WEEK`: 0-6 (Sunday=0, Saturday=6), range (e.g., 1-5 for Monday to Friday), or`*`

**Important notes about cron expressions:**

-**Minutes must always be`*`**: To ensure the schedule covers entire hours

-**Time ranges are continuous**: A range like`8-18` means from 8AM to 6:59PM (inclusive of both start and end hours)

-**Weekday ranges**:`1-5` means Monday through Friday (Monday=1, Friday=5)

-**No overlapping schedules**: The validation system prevents overlapping schedules.

**Example schedules:**

Prebuilt workspaces are not updated after they are provisioned.

[View issue](https://github.com/coder/internal/issues/364)

-**Autoscaling**

Prebuilt workspaces remain running until claimed. There's no automated mechanism to reduce instances during off-hours.

[View issue](https://github.com/coder/internal/issues/312)