vercel flags rollout adds progressive flag rollouts
Introduced 2026-04-15 · score 0.99
HOW TO USE IT
When staging a Vercel Flags rollout, run `vercel flags rollout <flag>` for the target environment with one or more percentage-and-duration stages. Set `--by` to a defined entity attribute for stable bucketing; for non-Boolean flags, specify the source and target variants, and optionally set the fallback, start time, and revision message.
vercel flags rollout <flag> --environment <environment> --by <entity.attribute> --stage <percentage,duration> [--stage <percentage,duration> ...]vercel flags rollout <flag> --environment <environment> --by <entity.attribute> --from-variant <variant> --to-variant <variant> [--default-variant <variant>] --stage <percentage,duration> [--stage <percentage,duration> ...] [--start <now|duration|ISO-8601-datetime>] [--message <text>]vercel flags rollout redesigned-checkout --environment production --by user.id --stage 5,6h --stage 10,6h --stage 25,12h --stage 50,1d --message "Start redesigned checkout rollout"WHY THIS HELPS
Stage a feature flag rollout while implementing or maintaining an application that uses Vercel flags.
REQUIREMENTS AND LIMITATIONS
- Version: 51.4.0
- <flag> (required): Flag slug to roll out.
- --environment <environment> (required): Target environment; valid values are `production`, `preview`, and `development`.
- --by <entity.attribute>: Entity attribute used for consistent bucketing; define the entity and attribute first. Timestamp attributes cannot be used for bucketing.
- --stage <percentage,duration> (required): Adds a stage defining the percentage sent to the rollout variant and how long the stage lasts. Repeat for more stages; example format: `5,6h`.
- --from-variant <variant> (required): Current variant for String, Number, and JSON rollouts; accepts a variant ID or value. Boolean rollouts default to `false`.
- --to-variant <variant> (required): Target variant for String, Number, and JSON rollouts; accepts a variant ID or value. Boolean rollouts default to `true`.
- --default-variant <variant>: Fallback variant served when the bucketing attribute is missing; accepts a variant ID or value. Boolean rollouts default to `false`.
- --start <time>: When the rollout begins: `now`, a future relative duration such as `1h`, or an ISO 8601 datetime.
- --message <text>: Optional revision message for the rollout.
- Prerequisite: Use an authenticated Vercel CLI and target a project. The CLI docs state that `--by` requires the entity and attribute to be defined first.
- Prerequisite: Vercel CLI must be installed and authenticated to manage flags from the terminal.
FIRST-PARTY EVIDENCE
- https://github.com/vercel/vercel/releases/tag/vercel%4051.4.0
- https://vercel.com/docs/cli/flags
- https://github.com/vercel/vercel/blob/main/skills/vercel-cli/references/flags.md
Check the installed version and the source before using it. Entry JSON