2 files changed, 67 insertions, 5 deletions
diff --git a/packages/meshbay-hub/src/meshbay_hub/daemon.py b/packages/meshbay-hub/src/meshbay_hub/daemon.py
index 024ca78..9609de6 100644
--- a/packages/meshbay-hub/src/meshbay_hub/daemon.py
+++ b/packages/meshbay-hub/src/meshbay_hub/daemon.py
@@ -35,6 +35,12 @@ def main() -> None:
     prune.add_argument("--log-level", default=argparse.SUPPRESS,
                        choices=["DEBUG", "INFO", "WARNING", "ERROR"])
 
+    migrate = sub.add_parser(
+        "migrate", help="bring the database schema up to date")
+    migrate.add_argument("--config", type=Path, default=argparse.SUPPRESS)
+    migrate.add_argument("--log-level", default=argparse.SUPPRESS,
+                         choices=["DEBUG", "INFO", "WARNING", "ERROR"])
+
     args = parser.parse_args()
 
     logging.basicConfig(
@@ -47,6 +53,9 @@ def main() -> None:
     if args.command == "prune-groups":
         sys.exit(asyncio.run(_prune_groups(cfg, args.days, args.dry_run)))
 
+    if args.command == "migrate":
+        sys.exit(_migrate(cfg))
+
     single_worker_or_exit(cfg.server.workers)
 
     uvicorn.run(
@@ -59,6 +68,45 @@ def main() -> None:
     )
 
 
+def migrations_dir() -> Path:
+    """Where this installation's migrations actually are.
+
+    Derived from the package rather than written down, because the one place a
+    path like this can be correct is next to the code it describes. The RPM
+    installs `meshbay_hub` into a shared venv and copies `alembic.ini` to
+    `/opt/meshbay-hub/migrations/`, where `%(here)s/src/meshbay_hub/db/…`
+    resolves to a directory that does not exist — so the packaged unit's
+    `ExecStartPre` could never have succeeded, and a hub installed from the
+    package would not start at all. The same `%(here)s` trap had already been
+    found once on the server, with a copy of alembic.ini pointing at a
+    month-old snapshot of the tree.
+    """
+    return Path(__file__).resolve().parent / "db" / "migrations"
+
+
+def _migrate(cfg) -> int:
+    """`alembic upgrade head`, with the paths resolved from the installation.
+
+    A command rather than a path in a unit file: it is correct for the RPM,
+    the DEB, a venv, and a checkout, and there is nothing to keep in step.
+    """
+    from alembic import command
+    from alembic.config import Config
+
+    scripts = migrations_dir()
+    if not (scripts / "versions").is_dir():
+        print(f"meshbay-hub: no migrations at {scripts}", file=sys.stderr)
+        return 1
+
+    alembic_cfg = Config()
+    alembic_cfg.set_main_option("script_location", str(scripts))
+    # `env.py` reads the URL from the environment the same way the server does,
+    # so the two cannot drift; this is set for the case where it does not.
+    alembic_cfg.set_main_option("sqlalchemy.url", cfg.db.url)
+    command.upgrade(alembic_cfg, "head")
+    return 0
+
+
 def single_worker_or_exit(workers: int) -> None:
     """Refuse to start with more than one worker.
 
diff --git a/packages/meshbay-hub/src/meshbay_hub/db/migrations/env.py b/packages/meshbay-hub/src/meshbay_hub/db/migrations/env.py
index f572716..8908deb 100644
--- a/packages/meshbay-hub/src/meshbay_hub/db/migrations/env.py
+++ b/packages/meshbay-hub/src/meshbay_hub/db/migrations/env.py
@@ -19,11 +19,25 @@ if config.config_file_name is not None:
 
 target_metadata = Base.metadata
 
-# Allow override via env var (production uses asyncpg, tests may use aiosqlite)
-db_url = os.environ.get(
-    "MESHBAY_DATABASE_URL",
-    "postgresql+asyncpg://meshbay:meshbay@localhost/meshbay_hub",
-)
+# Three sources, in the order that keeps them from disagreeing.
+#
+# A caller that already resolved the URL wins: `meshbay-hub migrate` passes
+# `cfg.db.url`, which is `load_config`'s answer — the very string the server
+# will connect with. Reading the environment again here instead would be a
+# second resolution of the same question, and the two would drift the day
+# anything but the environment decides it.
+#
+# Then the environment, for `alembic` run by hand or from a deploy script,
+# where `alembic.ini` carries only its placeholder. Then a local default, so
+# a developer's checkout needs no setup.
+_PLACEHOLDER = "driver://user:pass@localhost/dbname"
+
+db_url = config.get_main_option("sqlalchemy.url", "")
+if not db_url or db_url == _PLACEHOLDER:
+    db_url = os.environ.get(
+        "MESHBAY_DATABASE_URL",
+        "postgresql+asyncpg://meshbay:meshbay@localhost/meshbay_hub",
+    )
 config.set_main_option("sqlalchemy.url", db_url)