Added support for automatic database migrations.

Added Alembic environment and `run_db_migrations` logic to the entities
engine so database schema changes can be processed as soon as the
application is started.

platypush/entities/_base.py

@@ -1,12 +1,16 @@
 import logging
 import inspect
 import json
+import os
 import pathlib
+import subprocess
+import sys
 import types
 from datetime import datetime
-import pkgutil
 from typing import Callable, Dict, Final, Optional, Set, Type, Tuple, Any
 
+import pkgutil
+
 from dateutil.tz import tzutc
 from sqlalchemy import (
     Boolean,
@@ -23,6 +27,7 @@ from sqlalchemy import (
 from sqlalchemy.orm import ColumnProperty, backref, relationship
 from sqlalchemy.orm.exc import ObjectDeletedError
 
+import platypush
 from platypush.common.db import Base
 from platypush.message import JSONAble, Message
 
@@ -170,7 +175,10 @@ if 'entity' not in Base.metadata:
                 return normalized_name
             except ObjectDeletedError as e:
                 logger.warning(
-                    f'Could not access column "{col.key}" for entity ID "{self.id}": {e}'
+                    'Could not access column "%s" for entity ID "{%s}": {%s}',
+                    col.key,
+                    self.id,
+                    e,
                 )
                 return None
 
@@ -267,9 +275,9 @@ def _discover_entity_types():
                 isinstance(e, (ImportError, ModuleNotFoundError))
                 and modname[len(__package__) + 1 :] in _import_error_ignored_modules
             ):
-                logger.debug(f'Could not import module {modname}')
+                logger.debug('Could not import module %s', modname)
             else:
-                logger.warning(f'Could not import module {modname}')
+                logger.warning('Could not import module %s', modname)
                 logger.exception(e)
 
             continue
@@ -292,7 +300,31 @@ def init_entities_db():
     """
     from platypush.context import get_plugin
 
+    run_db_migrations()
     _discover_entity_types()
     db = get_plugin('db')
     assert db
     db.create_all(db.get_engine(), Base)
+
+
+def run_db_migrations():
+    """
+    Run the database migrations upon engine initialization.
+    """
+    logger.info('Running database migrations')
+    alembic_ini = os.path.join(
+        os.path.dirname(inspect.getabsfile(platypush)), 'migrations', 'alembic.ini'
+    )
+
+    subprocess.run(
+        [
+            sys.executable,
+            '-m',
+            'alembic',
+            '-c',
+            alembic_ini,
+            'upgrade',
+            'head',
+        ],
+        check=True,
+    )

platypush/migrations/alembic.ini

@@ -0,0 +1,106 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts
+script_location = %(here)s/alembic
+
+# template used to generate migration file names; The default value is %%(rev)s_%%(slug)s
+# Uncomment the line below if you want the files to be prepended with date and time
+# see https://alembic.sqlalchemy.org/en/latest/tutorial.html#editing-the-ini-file
+# for all available tokens
+# file_template = %%(year)d_%%(month).2d_%%(day).2d_%%(hour).2d%%(minute).2d-%%(rev)s_%%(slug)s
+
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.
+prepend_sys_path = .
+
+# timezone to use when rendering the date within the migration file
+# as well as the filename.
+# If specified, requires the python-dateutil library that can be
+# installed by adding `alembic[tz]` to the pip requirements
+# string value is passed to dateutil.tz.gettz()
+# leave blank for localtime
+# timezone =
+
+# max length of characters to apply to the
+# "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; This defaults
+# to alembic/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path.
+# The path separator used here should be the separator specified by "version_path_separator" below.
+version_locations = %(here)s/alembic/versions
+
+# version path separator; As mentioned above, this is the character used to split
+# version_locations. The default within new alembic.ini files is "os", which uses os.pathsep.
+# If this key is omitted entirely, it falls back to the legacy behavior of splitting on spaces and/or commas.
+# Valid values for version_path_separator are:
+#
+# version_path_separator = :
+# version_path_separator = ;
+# version_path_separator = space
+# Use os.pathsep. Default configuration used for new projects.
+version_path_separator = os
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+sqlalchemy.url = %(DB_ENGINE)s
+
+
+[post_write_hooks]
+# post_write_hooks defines scripts or Python functions that are run
+# on newly generated revision scripts.  See the documentation for further
+# detail and examples
+
+# format using "black" - use the console_scripts runner, against the "black" entrypoint
+# hooks = black
+# black.type = console_scripts
+# black.entrypoint = black
+# black.options = -l 79 REVISION_SCRIPT_FILENAME
+
+# Logging configuration
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

platypush/migrations/alembic/env.py

@@ -0,0 +1,92 @@
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+from platypush.config import Config
+from platypush.common.db import Base
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+target_metadata = Base.metadata
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+
+def run_migrations_offline() -> None:
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online() -> None:
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section, {}),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(connection=connection, target_metadata=target_metadata)
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+def set_db_engine():
+    db_conf = Config.get('db')
+    assert db_conf, 'Could not retrieve the database configuration'
+    engine = db_conf['engine']
+    assert engine, 'No database engine configured'
+
+    config = context.config
+    section = config.config_ini_section
+    config.set_section_option(section, 'DB_ENGINE', engine)
+
+
+set_db_engine()
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

platypush/migrations/alembic/script.py.mako

@@ -0,0 +1,24 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = ${repr(branch_labels)}
+depends_on = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

platypush/migrations/alembic/versions/d030953a871d_base_alembic_version.py

@@ -0,0 +1,22 @@
+"""Base alembic version
+
+Revision ID: d030953a871d
+Revises:
+Create Date: 2023-04-28 22:32:49.460118
+
+"""
+
+
+# revision identifiers, used by Alembic.
+revision = 'd030953a871d'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    pass
+
+
+def downgrade() -> None:
+    pass

requirements.txt

@@ -13,7 +13,8 @@ python-dateutil
 tz
 frozendict
 requests
-sqlalchemy<2.0.0
+sqlalchemy
+alembic
 bcrypt
 rsa
 zeroconf>=0.27.0

setup.py

@@ -38,6 +38,9 @@ setup(
     url="https://platypush.tech",
     packages=find_packages(),
     include_package_data=True,
+    package_data={
+        'platypush': ['alembic.ini', 'alembic/*', 'alembic/**/*'],
+    },
     entry_points={
         'console_scripts': [
             'platypush=platypush:main',
@@ -58,6 +61,7 @@ setup(
         'requests',
         'croniter',
         'sqlalchemy',
+        'alembic',
         'websockets',
         'websocket-client',
         'wheel',