Merge pull request #26 from Element84/migjob

Dockerfile

@@ -36,4 +36,5 @@ ENV PATH=/opt/swoop/db/swoop-db-venv/bin:$PATH
 
 RUN mkdir -p /opt/swoop/db/scripts
 COPY bin/db-initialization.py /opt/swoop/db/scripts/db-initialization.py
+COPY bin/run-migration-job.py /opt/swoop/db/scripts/run-migration-job.py
 ENV PATH=/opt/swoop/db/scripts:$PATH

bin/db-initialization.py

@@ -10,8 +10,8 @@
           swoop-caboose role username and password
     - CONDUCTOR_ROLE_USER and CONDUCTOR_ROLE_PASS:
           swoop-conductor role username and password
-    - MIGRATION_ROLE_USER and MIGRATION_ROLE_PASS:
-          username and password for migration role
+    - OWNER_ROLE_USER and OWNER_ROLE_PASS:
+          username and password for owner role
     - Any additional libpq-supported connection parameters
           (https://www.postgresql.org/docs/current/libpq-envars.html)
 """
@@ -24,8 +24,6 @@
 
 from swoop.db import SwoopDB
 
-OWNER_ROLE_NAME = "swoop"
-OWNER_ROLE = "OWNER_ROLE"
 APPLICATION_ROLES: list[str] = [
     "API_ROLE",
     "CABOOSE_ROLE",

bin/run-migration-job.py

@@ -0,0 +1,93 @@
+#!/usr/bin/env python
+"""
+This script automates applying migrations to a swoop database as created by
+./db-initialization.py. By default it will migrate the database forward to
+the most-recent schema version after waiting for all swoop application
+connections to be closed, but a few environment variables can be used to
+change that default behavior:
+
+    - ROLLBACK: boolean flag required when target version is less than current
+    - VERSION: the migration version to which to migrate/rollback the database
+    - NO_WAIT: override option to skip waiting for active connections to close
+
+The script uses standard libpq-supported connection environment variables
+(https://www.postgresql.org/docs/current/libpq-envars.html), so specify these
+as required to connect to the database. Common vars include:
+
+    - PGHOST: hostname or IP address of the postgres cluster host
+    - PGPORT: port number of the postgres server
+    - PGUSER: name of the user (role) that will perform the migrations
+    - PGPASSWORD: password of the user (role)
+    - PGDATABASE: name of the database onto which to apply migrations
+"""
+import asyncio
+import os
+import sys
+import time
+
+from swoop.db import SwoopDB
+
+
+def stderr(*args, **kwargs) -> None:
+    kwargs["file"] = sys.stderr
+    print(*args, **kwargs)
+
+
+def strtobool(val) -> bool:
+    """Convert a string representation of truth to true or false.
+    True values are 'y', 'yes', 't', 'true', 'on', and '1'; false values
+    are 'n', 'no', 'f', 'false', 'off', and '0'.  Raises ValueError if
+    'val' is anything else.
+    """
+    val = val.lower()
+    if val in ("y", "yes", "t", "true", "on", "1"):
+        return True
+    elif val in ("n", "no", "f", "false", "off", "0"):
+        return False
+    else:
+        raise ValueError(f"invalid boolean value {val!r}")
+
+
+def int_or_none(val):
+    return int(val) if val else None
+
+
+async def run_migrations() -> None:
+    rollback = strtobool(os.environ.get("ROLLBACK", "false"))
+    version = int_or_none(os.environ.get("VERSION"))
+    no_wait = strtobool(os.environ.get("NO_WAIT", "false"))
+
+    swoop_db = SwoopDB()
+
+    async with swoop_db.get_db_connection() as conn:
+        current_version = await swoop_db.get_current_version(conn=conn)
+        if current_version == version:
+            return
+        # Wait for all active connections from user roles to be closed
+        active_sessions = not no_wait
+        while active_sessions:
+            active_sessions = await conn.fetchval(
+                """
+                SELECT EXISTS(
+                    SELECT * FROM pg_stat_activity
+                    WHERE
+                        datname = current_database()
+                        AND usename != current_user
+                )
+                """,
+            )
+            if active_sessions:
+                time.sleep(2)
+
+        if rollback:
+            stderr(f"Rolling back database to version {version}")
+            direction = "down"
+        else:
+            stderr(f"Migrating database to version {version}")
+            direction = "up"
+
+        await swoop_db.migrate(target=version, direction=direction, conn=conn)
+
+
+if __name__ == "__main__":
+    asyncio.run(run_migrations())