test(cloud-store): verify schema migrations

packages/cloud-platform/cloud/migrations/alembic.ini

@@ -1,6 +1,7 @@
 [alembic]
 script_location = %(here)s
 prepend_sys_path = .
+path_separator = os
 sqlalchemy.url = sqlite:///cloud/cloud.sqlite3
 
 [loggers]

packages/cloud-platform/cloud/migrations/versions/0001_cloud_repository.py

@@ -12,13 +12,13 @@ branch_labels = None
 depends_on = None
 
 
-LEASE_COLUMNS = (
-    sa.Column("attempt_count", sa.Integer(), nullable=False, server_default="0"),
-    sa.Column("lease_id", sa.String(), nullable=True),
-    sa.Column("lease_expires_at", sa.String(), nullable=True),
-    sa.Column("failure_reason", sa.Text(), nullable=True),
-    sa.Column("result_json", sa.Text(), nullable=True),
-    sa.Column("updated_at", sa.String(), nullable=True),
+LEASE_COLUMN_NAMES = (
+    "attempt_count",
+    "lease_id",
+    "lease_expires_at",
+    "failure_reason",
+    "result_json",
+    "updated_at",
 )
 
 
@@ -32,9 +32,9 @@ def upgrade() -> None:
             column["name"] for column in inspector.get_columns("scheduled_tasks")
         }
         with op.batch_alter_table("scheduled_tasks") as batch:
-            for column in LEASE_COLUMNS:
+            for column in _lease_columns():
                 if column.name not in existing_columns:
-                    batch.add_column(column.copy())
+                    batch.add_column(column)
 
     inspector = sa.inspect(op.get_bind())
     if "task_attempts" not in inspector.get_table_names():
@@ -52,9 +52,9 @@ def downgrade() -> None:
         column["name"] for column in inspector.get_columns("scheduled_tasks")
     }
     with op.batch_alter_table("scheduled_tasks") as batch:
-        for column in reversed(LEASE_COLUMNS):
-            if column.name in existing_columns:
-                batch.drop_column(column.name)
+        for column_name in reversed(LEASE_COLUMN_NAMES):
+            if column_name in existing_columns:
+                batch.drop_column(column_name)
 
 
 def _create_base_tables() -> None:
@@ -82,7 +82,7 @@ def _create_base_tables() -> None:
         sa.Column("status", sa.String(), nullable=False),
         sa.Column("assigned_device_id", sa.String(), nullable=True),
         sa.Column("assigned_host_id", sa.String(), nullable=True),
-        *[column.copy() for column in LEASE_COLUMNS],
+        *_lease_columns(),
         sa.Column("created_at", sa.String(), nullable=False),
     )
     op.create_table(
@@ -110,3 +110,14 @@ def _create_attempts_table() -> None:
         sa.Column("failure_reason", sa.Text(), nullable=True),
         sa.Column("result_json", sa.Text(), nullable=True),
     )
+
+
+def _lease_columns() -> tuple[sa.Column, ...]:
+    return (
+        sa.Column("attempt_count", sa.Integer(), nullable=False, server_default="0"),
+        sa.Column("lease_id", sa.String(), nullable=True),
+        sa.Column("lease_expires_at", sa.String(), nullable=True),
+        sa.Column("failure_reason", sa.Text(), nullable=True),
+        sa.Column("result_json", sa.Text(), nullable=True),
+        sa.Column("updated_at", sa.String(), nullable=True),
+    )

packages/cloud-platform/cloud/schema.py

@@ -0,0 +1,58 @@
+from __future__ import annotations
+
+from pathlib import Path
+
+from alembic import command
+from alembic.config import Config
+from alembic.runtime.migration import MigrationContext
+
+from cloud.database import create_database_engine, normalize_database_url
+
+
+HEAD_REVISION = "0001_cloud_repository"
+
+
+class SchemaVersionError(RuntimeError):
+    """Raised when the database schema is not at the required revision."""
+
+
+def upgrade_database(database_url: str, revision: str = "head") -> None:
+    command.upgrade(_alembic_config(database_url), revision)
+
+
+def downgrade_database(database_url: str, revision: str = "base") -> None:
+    command.downgrade(_alembic_config(database_url), revision)
+
+
+def current_revision(database_url: str) -> str | None:
+    engine = create_database_engine(database_url)
+    try:
+        with engine.connect() as connection:
+            context = MigrationContext.configure(connection)
+            return context.get_current_revision()
+    finally:
+        engine.dispose()
+
+
+def is_schema_current(database_url: str) -> bool:
+    return current_revision(database_url) == HEAD_REVISION
+
+
+def require_current_schema(database_url: str) -> None:
+    revision = current_revision(database_url)
+    if revision != HEAD_REVISION:
+        raise SchemaVersionError(
+            f"cloud database schema is {revision or 'unversioned'}; "
+            f"required revision is {HEAD_REVISION}"
+        )
+
+
+def _alembic_config(database_url: str) -> Config:
+    migrations_dir = Path(__file__).resolve().parent / "migrations"
+    config = Config(str(migrations_dir / "alembic.ini"))
+    config.set_main_option("script_location", str(migrations_dir))
+    config.set_main_option(
+        "sqlalchemy.url",
+        normalize_database_url(database_url).replace("%", "%%"),
+    )
+    return config