Schema modules and targets

Available since: v1.0

A SurrealKit project applies one set of schema files to one database. That covers most projects and needs no configuration. When a project outgrows it, surrealkit.toml can declare schema modules - independently tracked sets of .surql files - and targets - named databases to apply them to.

The two combine into a matrix. Selecting two modules and three targets gives six pairs, applied one at a time.

The default project

With no [schema.*] sections, a project has a single unnamed module at database/schema, applied to the connection given by --host, --ns and --db. This is the pre-1.0 layout and nothing about it changed, so an existing project keeps working untouched. Everything below is additive.

Declaring modules

Each [schema.<name>] section names a module. Files live under database/modules/<name>/:

[schema.core]

[schema.billing]
depends_on = ["core"]

database/
├── schema/                    # the default module, unchanged
└── modules/
    ├── core/
    │   └── schema/
    └── billing/
        └── schema/

Each module gets its own directories for the artefacts that belong to a schema. Tests and setup.surql belong to the project rather than to any one module, so they are not module-scoped:

Named modules sit under modules/ rather than inside database/schema because the default module walks its schema directory recursively. Nesting a named module inside it would make the default module collect those files and claim ownership of them. Set [schema.<name>] path to put a module somewhere else entirely.

Dependencies

depends_on orders application, so a module is never applied before something it depends on. Selecting a module also selects its dependencies, the way cargo build -p does. Pass --no-deps to select only what you named. Independent modules are ordered alphabetically so runs are reproducible, and dependency cycles are rejected before anything touches a database.

Independent tracking

Each module owns its own metadata, which is what makes modules safe to mix in one database: a module only ever prunes its own objects. Without that, syncing one schema against a database another schema had populated would remove the other's tables.

SurrealKit partitions the __entity table by module. The ns field is a partition key here, unrelated to a SurrealDB namespace:

Pre-1.0 rows already sit in the unqualified partitions, which is why adopting modules needs no migration: existing schema stays the default module with its metadata intact.

Declaring targets

Each [target.<name>] section names a database. A target inherits everything it does not set from the ambient connection, so it usually names only ns and db:

[target.acme]
ns = "acme"
db = "prod"
pass_env = "ACME_DB_PASSWORD"
primary = true

[target.globex]
ns = "globex"
db = "prod"
pass_env = "GLOBEX_DB_PASSWORD"

Passwords are read from the environment through pass_env, never from the file. A literal pass or password key is rejected, and a pass_env naming an unset variable fails before any connection opens, so a misconfigured target cannot leave a fan-out half applied. See Configuration for the full key reference.

A target can also point at a different instance entirely, which is the usual shape for promoting the same schema from staging to production:

[target.staging]
host = "wss://staging-4pq7.aws-euw1.surreal.cloud"
ns = "main"
db = "main"
pass_env = "STAGING_DB_PASSWORD"

[target.production]
host = "wss://production-6xk2.aws-euw1.surreal.cloud"
ns = "main"
db = "main"
pass_env = "PRODUCTION_DB_PASSWORD"

Get the endpoint for a Cloud instance with surrealctl instance endpoint.

Restricting modules per target

schemas limits which modules apply to a target. An analytics database that needs the shared tables but not the billing ones declares only what it wants:

[target.warehouse]
ns = "internal"
db = "analytics"
schemas = ["core", "analytics"]
pass_env = "WAREHOUSE_DB_PASSWORD"

Selecting what to apply

surrealkit sync                              # every declared module, primary target
surrealkit sync --schema billing             # billing, and core because billing depends on it
surrealkit sync --schema billing --no-deps   # billing alone
surrealkit sync --target acme                # every module, one target
surrealkit sync --all                        # the full matrix
surrealkit sync --all --keep-going           # do not stop at the first failure

Omitting --schema selects every declared module, or the default module when none are declared. Targets resolve in this order, first match winning:

1. 1.

   Every --target given.

2. 2.

   Every declared target, when --all is passed.

3. 3.

   The target marked primary = true.

4. 4.

   The only declared target, when exactly one exists.

5. 5.

   The ambient connection from --host, --ns and --db.

How a fan-out runs

Targets are applied one at a time. Within a target, modules stop at the first failure, because they are dependency-ordered and the rest would build on a broken base. Targets also stop at the first failure unless you pass --keep-going.

There is no transaction across databases, so a failed run can leave some targets applied and others not. Every operation is idempotent, so re-running after a fix is safe.

When a run covers more than one pair, SurrealKit prints a summary and exits non-zero if any pair failed:

  schema   target   status
  ------   ------   ------
  core     acme     ok
  billing  acme     FAILED

1 ok, 1 failed

Empty source sets

Before opening any connection, SurrealKit resolves every selected module and refuses if one has no .surql files. A wrong working directory or --folder value would otherwise look like a schema that had been deleted, and sync would prune the database to match:

refusing filesystem sync: schema_module=billing resolved_schema_dir=./database/modules/billing/schema source_count=0; check --folder / SURREALDB_FOLDER and module selection, or pass --allow-empty-prune if the empty source set is intentional

Pass --allow-empty-prune when the empty source set is deliberate and you do want everything removed. The check also covers --dry-run, --no-prune and the first sync of a --watch session, because an empty selection cannot otherwise be told apart from a wrong path. A selection where no module applies to any target stays an error rather than a successful no-op.

Beta limitations

--schema, --target, --all and --keep-going are accepted on every subcommand, but not every subcommand acts on them yet. In 1.0.0-beta.1:

Everything in the "No" column uses the ambient connection from --host, --ns and --db, and the default module's directories. surrealkit seed --schema billing therefore seeds database/seed rather than database/modules/billing/seed, and surrealkit typegen --target acme introspects the ambient database. Pass the connection explicitly for those commands until this is resolved.

--watch refuses a selection covering more than one module or target, because watching a whole matrix on a timer is rarely what you want.

Next steps

• •

  Configuration: the full surrealkit.toml key reference

• •

  Sync: apply schema files to a database

• •

  Rollouts: phased migrations for shared databases