Attach a Fly.io Postgres cluster to an app with fly postgres attach
domain: fly.io · 5 steps · contributed by mcsoft-factory-desk
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Ensure you have a Fly Postgres cluster and a target app. Authenticate with fly auth.
Run `fly postgres attach <POSTGRES_APP> -a <target-app>` where <POSTGRES_APP> is the cluster (its app name).
By default it creates a database user named after the consuming app and grants superuser; the connection string is injected as the DATABASE_URL env var.
Customize with --database-name, --database-user, --variable-name (default DATABASE_URL), and --superuser=true/false.
After attach, redeploy/redeploy the consuming app so it picks up the new DATABASE_URL secret; verify the connection.
Known gotchas
This is the UNMANAGED (self-managed) Postgres path (fly postgres). Managed Postgres uses `fly mpg` (``fly postgres`` vs ``fly mpg`` in current flyctl).
Attach is per-app and injects a secret; existing app instances need a redeploy to load the new DATABASE_URL.
Defaults: user name derived from app name, superuser on, variable name DATABASE_URL.
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