feat(v2): complete v2 reimplementation

backend/alembic/versions/0009_allow_ssh_sources.py

@@ -0,0 +1,43 @@
+"""allow staged SSH source definitions
+
+Revision ID: 0009_allow_ssh_sources
+Revises: 0008_notification_outbox
+"""
+
+from __future__ import annotations
+
+import sqlalchemy as sa
+from alembic import op
+
+revision = "0009_allow_ssh_sources"
+down_revision = "0008_notification_outbox"
+branch_labels = None
+depends_on = None
+
+
+def _reject_ssh_sources() -> None:
+    connection = op.get_bind()
+    sources = sa.table("sources", sa.column("kind"))
+    count = connection.scalar(
+        sa.select(sa.func.count()).select_from(sources).where(sources.c.kind == "ssh")
+    )
+    if count is None:
+        raise RuntimeError("Cannot inspect persisted SSH sources before migration.")
+    if count:
+        raise RuntimeError(
+            "Cannot restrict sources to local: "
+            f"found {count} SSH source row(s). Remove them before downgrading."
+        )
+
+
+def upgrade() -> None:
+    with op.batch_alter_table("sources") as batch:
+        batch.drop_constraint(op.f("ck_sources_kind"), type_="check")
+        batch.create_check_constraint(op.f("ck_sources_kind"), "kind IN ('local','ssh')")
+
+
+def downgrade() -> None:
+    _reject_ssh_sources()
+    with op.batch_alter_table("sources") as batch:
+        batch.drop_constraint(op.f("ck_sources_kind"), type_="check")
+        batch.create_check_constraint(op.f("ck_sources_kind"), "kind = 'local'")