[GitHub] [airflow] potiuk commented on a change in pull request #18439: Check and run migration in webserver startup if necessary

[GitBox <gi...@apache.org>]

potiuk commented on a change in pull request #18439:
URL: https://github.com/apache/airflow/pull/18439#discussion_r716075733



##########
File path: airflow/utils/db.py
##########
@@ -626,27 +627,74 @@ def check_migrations(timeout):
     :param timeout: Timeout for the migration in seconds
     :return: None
     """
-    from alembic.runtime.migration import MigrationContext
+    ticker = 0
+    while True:
+        source_heads = get_source_heads()
+        db_heads = get_db_heads()
+        if source_heads == db_heads:
+            break
+        if ticker >= timeout:
+            raise TimeoutError(
+                f"There are still unapplied migrations after {ticker} seconds. "
+                f"Migration Head(s) in DB: {db_heads} | Migration Head(s) in Source Code: {source_heads}"
+            )
+        ticker += 1
+        time.sleep(1)
+        log.info('Waiting for migrations... %s second(s)', ticker)
+
+
+def get_source_heads():
+    """
+    Function to get the current migration head in the source code.
+
+    :return: List of migration head(s)
+    """
     from alembic.script import ScriptDirectory
 
     config = _get_alembic_config()
     script_ = ScriptDirectory.from_config(config)
+    return set(script_.get_heads())
+
+
+def get_db_heads():
+    """
+    Function to get the current migration head in the database.
+
+    :return: List of migration head(s)
+    """
+    from alembic.runtime.migration import MigrationContext
+
     with settings.engine.connect() as connection:
         context = MigrationContext.configure(connection)
-        ticker = 0
-        while True:
-            source_heads = set(script_.get_heads())
-            db_heads = set(context.get_current_heads())
-            if source_heads == db_heads:
-                break
-            if ticker >= timeout:
-                raise TimeoutError(
-                    f"There are still unapplied migrations after {ticker} seconds. "
-                    f"Migration Head(s) in DB: {db_heads} | Migration Head(s) in Source Code: {source_heads}"
-                )
-            ticker += 1
-            time.sleep(1)
-            log.info('Waiting for migrations... %s second(s)', ticker)
+        return set(context.get_current_heads())
+
+
+def check_and_run_migrations(source_heads, db_heads):
+    """Check and run migrations if necessary. Only use in a tty"""
+    from rich import print as rich_print
+
+    source_heads = get_source_heads()
+    db_heads = get_db_heads()
+    if len(db_heads) < 0:
+        if sys.stdout.isatty():
+            # initialize database
+            print("DB: " + repr(settings.engine.url))
+            initdb()
+            print("DB Initialization done")
+        else:
+            rich_print("[red][bold]ERROR:[/bold] You need to initialize the database")

Review comment:
       Both I think - there is a chance that running Airflow on non-migrated DB might cause some data corruption - I think this is perfectly fine to exit immediately if we have wrong (even with sys.exit() rather than throwing exceptions). 




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