Added `--db` CLI option and support for configuration over environment.

Closes: #280

platypush/app/_app.py

@@ -1,5 +1,6 @@
 from contextlib import contextmanager
 import logging
+import pathlib
 import os
 import signal
 import subprocess
@@ -41,6 +42,7 @@ class Application:
         self,
         config_file: Optional[str] = None,
         workdir: Optional[str] = None,
+        db: Optional[str] = None,
         logsdir: Optional[str] = None,
         cachedir: Optional[str] = None,
         device_id: Optional[str] = None,
@@ -56,30 +58,87 @@ class Application:
         ctrl_sock: Optional[str] = None,
     ):
         """
-        :param config_file: Configuration file override (default: None).
+        :param config_file: Configuration file. The order of precedence is:
-        :param workdir: Overrides the ``workdir`` setting in the configuration
+
-            file (default: None).
+            - The ``config_file`` parameter (or the ``-c``/``--config`` command
-        :param logsdir: Set logging directory. If not specified, the
+              line argument).
-            ``filename`` setting under the ``logging`` section of the
+            - The ``PLATYPUSH_CONFIG`` environment variable.
-            configuration file is used. If not set, logging will be sent to
+            - ``./config.yaml``
-            stdout and stderr.
+            - ``~/.config/platypush/config.yaml``
-        :param cachedir: Overrides the ``cachedir`` setting in the configuration
+            - ``/etc/platypush/config.yaml``
-            file (default: None).
+
-        :param device_id: Override the device ID used to identify this
+        :param workdir: Working directory where the application will store its
-            instance. If not passed here, it is inferred from the configuration
+            data and integration plugins will store their data. The order of
-            (device_id field). If not present there either, it is inferred from
+            precedence is:
-            the hostname.
+
+                - The ``workdir`` parameter (or the ``-w``/``--workdir`` command
+                  line argument).
+                - The ``PLATYPUSH_WORKDIR`` environment variable.
+                - The ``workdir`` field in the configuration file.
+                - ``~/.local/share/platypush``
+
+        :param db: Main database engine for the application. Supports SQLAlchemy
+            engine strings. The order of precedence is:
+
+                - The ``db`` parameter (or the ``--main-db``/``--db`` command
+                  line argument).
+                - The ``PLATYPUSH_DB`` environment variable.
+                - The ``db`` field in the configuration file.
+                - ``sqlite:///<workdir>/main.db``
+
+        :param logsdir: Logs directory where the application will store its logs.
+            The order of precedence is:
+
+                - The ``logsdir`` parameter (or the ``-l``/``--logsdir`` command
+                  line argument).
+                - The ``PLATYPUSH_LOGSDIR`` environment variable.
+                - The ``logging`` -> ``filename`` field in the configuration
+                  file (the ``format`` and ``level`` fields can be set as well
+                  using Python logging configuration).
+                - stdout and stderr
+
+        :param cachedir: Directory where the application and the plugins will store
+            their cache data. The order of precedence is:
+
+                - The ``cachedir`` parameter (or the ``--cachedir`` command line
+                  argument).
+                - The ``PLATYPUSH_CACHEDIR`` environment variable.
+                - The ``cachedir`` field in the configuration file.
+                - ``~/.cache/platypush``
+
+        :param device_id: Device ID used to identify this instance. The order
+            of precedence is:
+
+              - The ``device_id`` parameter (or the ``--device-id`` command
+                line argument).
+              - The ``PLATYPUSH_DEVICE_ID`` environment variable.
+              - The ``device_id`` field in the configuration file.
+              - The hostname of the machine.
+
         :param pidfile: File where platypush will store its PID upon launch,
            useful if you're planning to integrate the application within a
-           service or a launcher script (default: None).
+           service or a launcher script. Order of precedence:
+
+               - The ``pidfile`` parameter (or the ``-P``/``--pidfile`` command
+                 line argument).
+               - The ``PLATYPUSH_PIDFILE`` environment variable.
+               - No PID file.
+
         :param requests_to_process: Exit after processing the specified
-            number of requests (default: None, loop forever).
+            number of requests (default: None, loop forever). This is usually
+            useful for testing purposes.
         :param no_capture_stdout: Set to true if you want to disable the
             stdout capture by the logging system (default: False).
         :param no_capture_stderr: Set to true if you want to disable the
             stderr capture by the logging system (default: False).
         :param redis_queue: Name of the (Redis) queue used for dispatching
-            messages (default: platypush/bus).
+            messages. Order of precedence:
+
+                - The ``redis_queue`` parameter (or the ``--redis-queue`` command
+                  line argument).
+                - The ``PLATYPUSH_REDIS_QUEUE`` environment variable.
+                - ``platypush/bus``
+
         :param verbose: Enable debug/verbose logging, overriding the stored
             configuration (default: False).
         :param start_redis: If set, it starts a managed Redis instance upon
@@ -87,34 +146,57 @@ class Application:
             server). This is particularly useful when running the application
             inside of Docker containers, without relying on ``docker-compose``
             to start multiple containers, and in tests (default: False).
-        :param redis_host: Host of the Redis server to be used. It overrides
+        :param redis_host: Host of the Redis server to be used. The order of
-            the settings in the ``redis`` section of the configuration file.
+            precedence is:
-        :param redis_port: Port of the local Redis server. It overrides the
+
-            settings in the ``redis`` section of the configuration file.
+                - The ``redis_host`` parameter (or the ``--redis-host`` command
+                  line argument).
+                - The ``PLATYPUSH_REDIS_HOST`` environment variable.
+                - The ``redis`` -> ``host`` field in the configuration file.
+                - The ``backend.redis`` -> ``redis_args`` -> ``host`` field in
+                  the configuration file.
+                - ``localhost``
+
+        :param redis_port: Port of the Redis server to be used. The order of
+            precedence is:
+
+                - The ``redis_port`` parameter (or the ``--redis-port`` command
+                  line argument).
+                - The ``PLATYPUSH_REDIS_PORT`` environment variable.
+                - The ``redis`` -> ``port`` field in the configuration file.
+                - The ``backend.redis`` -> ``redis_args`` -> ``port`` field in
+                  the configuration file.
+                - ``6379``
+
         :param ctrl_sock: If set, it identifies a path to a UNIX domain socket
             that the application can use to send control messages (e.g. STOP
             and RESTART) to its parent.
         """
 
-        self.pidfile = pidfile
+        self.pidfile = pidfile or os.environ.get('PLATYPUSH_PIDFILE')
         self.bus: Optional[Bus] = None
-        self.redis_queue = redis_queue or RedisBus.DEFAULT_REDIS_QUEUE
+        self.redis_queue = (
-        self.config_file = config_file
+            redis_queue
-        self._verbose = verbose
+            or os.environ.get('PLATYPUSH_REDIS_QUEUE')
-        self._logsdir = (
+            or RedisBus.DEFAULT_REDIS_QUEUE
-            os.path.abspath(os.path.expanduser(logsdir)) if logsdir else None
         )
+        self.config_file = config_file or os.environ.get('PLATYPUSH_CONFIG')
+        self.verbose = verbose
+        self.db_engine = db or os.environ.get('PLATYPUSH_DB')
+        self.device_id = device_id or os.environ.get('PLATYPUSH_DEVICE_ID')
 
+        self.logsdir = self.expand_path(logsdir or os.environ.get('PLATYPUSH_LOGSDIR'))
+        self.workdir = self.expand_path(workdir or os.environ.get('PLATYPUSH_WORKDIR'))
+        self.cachedir = self.expand_path(
+            cachedir or os.environ.get('PLATYPUSH_CACHEDIR')
+        )
         Config.init(
             self.config_file,
-            device_id=device_id,
+            device_id=self.device_id,
-            workdir=os.path.abspath(os.path.expanduser(workdir)) if workdir else None,
+            workdir=self.workdir,
-            cachedir=os.path.abspath(os.path.expanduser(cachedir))
+            db=self.db_engine,
-            if cachedir
+            cachedir=self.cachedir,
-            else None,
+            ctrl_sock=self.expand_path(ctrl_sock),
-            ctrl_sock=os.path.abspath(os.path.expanduser(ctrl_sock))
-            if ctrl_sock
-            else None,
         )
 
         self.no_capture_stdout = no_capture_stdout
@@ -125,24 +207,25 @@ class Application:
         self.processed_requests = 0
         self.cron_scheduler = None
         self.start_redis = start_redis
-        self.redis_host = redis_host
+        self.redis_host = redis_host or os.environ.get('PLATYPUSH_REDIS_HOST')
-        self.redis_port = redis_port
+        self.redis_port = redis_port or os.environ.get('PLATYPUSH_REDIS_PORT')
-        self.redis_conf = {}
+        self._redis_conf = {
+            'host': self.redis_host or 'localhost',
+            'port': self.redis_port or self._default_redis_port,
+        }
+
         self._redis_proc: Optional[subprocess.Popen] = None
         self.cmd_stream = CommandStream(ctrl_sock)
 
         self._init_bus()
         self._init_logging()
 
+    @staticmethod
+    def expand_path(path: Optional[str]) -> Optional[str]:
+        return os.path.abspath(os.path.expanduser(path)) if path else None
+
     def _init_bus(self):
-        self._redis_conf = get_redis_conf()
+        self._redis_conf = {**self._redis_conf, **get_redis_conf()}
-        self._redis_conf['port'] = self.redis_port or self._redis_conf.get(
-            'port', self._default_redis_port
-        )
-
-        if self.redis_host:
-            self._redis_conf['host'] = self.redis_host
-
         Config.set('redis', self._redis_conf)
         self.bus = RedisBus(
             redis_queue=self.redis_queue,
@@ -152,12 +235,18 @@ class Application:
 
     def _init_logging(self):
         logging_conf = Config.get('logging') or {}
-        if self._verbose:
+        if self.verbose:
             logging_conf['level'] = logging.DEBUG
-        if self._logsdir:
+
-            logging_conf['filename'] = os.path.join(self._logsdir, 'platypush.log')
+        if self.logsdir:
+            logging_conf['filename'] = os.path.join(self.logsdir, 'platypush.log')
             logging_conf.pop('stream', None)
 
+        if logging_conf.get('filename'):
+            pathlib.Path(os.path.dirname(logging_conf['filename'])).mkdir(
+                parents=True, exist_ok=True
+            )
+
         Config.set('logging', logging_conf)
         logging.basicConfig(**logging_conf)
 
@@ -214,6 +303,7 @@ class Application:
             workdir=opts.workdir,
             cachedir=opts.cachedir,
             logsdir=opts.logsdir,
+            db=opts.db_engine,
             device_id=opts.device_id,
             pidfile=opts.pidfile,
             no_capture_stdout=opts.no_capture_stdout,

platypush/backend/redis/__init__.py

@@ -1,43 +1,41 @@
 import json
-from typing import Optional, Union
+from typing import Any, Dict, Optional, Union
 
 from redis import Redis
 
 from platypush.backend import Backend
-from platypush.context import get_plugin
 from platypush.message import Message
+from platypush.utils import get_redis_conf
 
 
 class RedisBackend(Backend):
     """
     Backend that reads messages from a configured Redis queue (default:
-    ``platypush_bus_mq``) and posts them to the application bus.  Very
+    ``platypush/backend/redis``) and forwards them to the application bus.
-    useful when you have plugin whose code is executed in another process
+
+    Useful when you have plugin whose code is executed in another process
     and can't post events or requests to the application bus.
     """
 
-    def __init__(self, *args, queue='platypush_bus_mq', redis_args=None, **kwargs):
+    def __init__(
+        self,
+        *args,
+        queue: str = 'platypush/backend/redis',
+        redis_args: Optional[Dict[str, Any]] = None,
+        **kwargs
+    ):
         """
-        :param queue: Queue name to listen on (default: ``platypush_bus_mq``)
+        :param queue: Name of the Redis queue to listen to (default:
-        :type queue: str
+            ``platypush/backend/redis``).
 
-        :param redis_args: Arguments that will be passed to the redis-py constructor (e.g. host, port, password), see
+        :param redis_args: Arguments that will be passed to the redis-py
-            https://redis-py.readthedocs.io/en/latest/
+            constructor (e.g. host, port, password). See
-        :type redis_args: dict
+            https://redis-py.readthedocs.io/en/latest/connections.html#redis.Redis
+            for supported parameters.
         """
-
         super().__init__(*args, **kwargs)
-        if redis_args is None:
+        self.redis_args = redis_args or get_redis_conf()
-            redis_args = {}
-
         self.queue = queue
-
-        if not redis_args:
-            redis_plugin = get_plugin('redis')
-            if redis_plugin and redis_plugin.kwargs:
-                redis_args = redis_plugin.kwargs
-
-        self.redis_args = redis_args
         self.redis: Optional[Redis] = None
 
     def send_message(
@@ -47,20 +45,21 @@ class RedisBackend(Backend):
         Send a message to a Redis queue.
 
         :param msg: Message to send, as a ``Message`` object or a string.
-        :param queue_name: Queue name to send the message to (default: ``platypush_bus_mq``).
+        :param queue_name: Queue name to send the message to (default:
+            configured ``queue`` value).
         """
-
         if not self.redis:
             self.logger.warning('The Redis backend is not yet running.')
             return
 
         self.redis.rpush(queue_name or self.queue, str(msg))
 
-    def get_message(self, queue_name=None):
+    def get_message(self, queue_name: Optional[str] = None) -> Optional[Message]:
         queue = queue_name or self.queue
+        assert self.redis, 'The Redis backend is not yet running.'
         data = self.redis.blpop(queue, timeout=1)
         if data is None:
-            return
+            return None
 
         msg = data[1].decode()
         try:
@@ -68,15 +67,9 @@ class RedisBackend(Backend):
         except Exception as e:
             self.logger.debug(str(e))
             try:
-                import ast
+                msg = json.loads(msg)
-
-                msg = Message.build(ast.literal_eval(msg))
             except Exception as ee:
-                self.logger.debug(str(ee))
+                self.logger.exception(ee)
-                try:
-                    msg = json.loads(msg)
-                except Exception as eee:
-                    self.logger.exception(eee)
 
         return msg
 

platypush/cli.py

@@ -32,6 +32,18 @@ def parse_cmdline(args: Sequence[str]) -> argparse.Namespace:
         help='Custom working directory to be used for the application',
     )
 
+    parser.add_argument(
+        '--main-db',
+        '--db',
+        dest='db_engine',
+        required=False,
+        default=None,
+        help='Custom database engine to be used for the application '
+        '(e.g. sqlite:///:memory: or sqlite:///path/to/db.sqlite). '
+        'If missing, it falls back to the value of the `main.db` setting in the configuration file. '
+        'If missing, it falls back to sqlite://<workdir>/main.db.',
+    )
+
     parser.add_argument(
         '--cachedir',
         dest='cachedir',

platypush/config/__init__.py

@@ -97,6 +97,7 @@ class Config:
         cfgfile: Optional[str] = None,
         workdir: Optional[str] = None,
         cachedir: Optional[str] = None,
+        db: Optional[str] = None,
     ):
         """
         Constructor. Always use the class as a singleton (i.e. through
@@ -106,6 +107,7 @@ class Config:
             location in _cfgfile_locations).
         :param workdir: Overrides the default working directory.
         :param cachedir: Overrides the default cache directory.
+        :param db: Overrides the default database connection string.
         """
 
         self.backends = {}
@@ -124,7 +126,7 @@ class Config:
 
         self._init_secrets()
         self._init_dirs(workdir=workdir, cachedir=cachedir)
-        self._init_db()
+        self._init_db(db=db)
         self._init_logging()
         self._init_device_id()
         self._init_environment()
@@ -175,7 +177,14 @@ class Config:
 
         self._config['logging'] = logging_config
 
-    def _init_db(self):
+    def _init_db(self, db: Optional[str] = None):
+        # If the db connection string is passed as an argument, use it
+        if db:
+            self._config['db'] = {
+                'engine': db,
+            }
+            return
+
         # Initialize the default db connection string
         db_engine = self._config.get('main.db', '')
         if db_engine:
@@ -474,6 +483,7 @@ class Config:
         cfgfile: Optional[str] = None,
         workdir: Optional[str] = None,
         cachedir: Optional[str] = None,
+        db: Optional[str] = None,
         force_reload: bool = False,
     ) -> "Config":
         """
@@ -481,7 +491,7 @@ class Config:
         """
         if force_reload or cls._instance is None:
             cfg_args = [cfgfile] if cfgfile else []
-            cls._instance = Config(*cfg_args, workdir=workdir, cachedir=cachedir)
+            cls._instance = Config(*cfg_args, workdir=workdir, cachedir=cachedir, db=db)
         return cls._instance
 
     @classmethod
@@ -546,6 +556,7 @@ class Config:
         device_id: Optional[str] = None,
         workdir: Optional[str] = None,
         cachedir: Optional[str] = None,
+        db: Optional[str] = None,
         ctrl_sock: Optional[str] = None,
         **_,
     ):
@@ -556,10 +567,11 @@ class Config:
         :param device_id: Override the configured device_id.
         :param workdir: Override the configured working directory.
         :param cachedir: Override the configured cache directory.
+        :param db: Override the configured database connection string.
         :param ctrl_sock: Override the configured control socket.
         """
         cfg = cls._get_instance(
-            cfgfile, workdir=workdir, cachedir=cachedir, force_reload=True
+            cfgfile, workdir=workdir, cachedir=cachedir, db=db, force_reload=True
         )
         if device_id:
             cfg.set('device_id', device_id)
@@ -567,6 +579,8 @@ class Config:
             cfg.set('workdir', workdir)
         if cachedir:
             cfg.set('cachedir', cachedir)
+        if db:
+            cfg.set('db', db)
         if ctrl_sock:
             cfg.set('ctrl_sock', ctrl_sock)
 

platypush/config/config.yaml

@@ -87,15 +87,20 @@
 # # `workdir`. You can specify any other engine string here - the application has
 # # been tested against SQLite, Postgres and MariaDB/MySQL >= 8.
 # #
+# # You can also specify a custom database engine at runtime (SQLAlchemy syntax
+# # supported) through the `--db` argument otherwise.
+# #
 # # NOTE: If you want to use a DBMS other than SQLite, then you will also need to
 # # ensure that a compatible Python driver is installed on the system where
 # # Platypush is running. For example, Postgres will require the Python pg8000,
 # # psycopg or another compatible driver.
 #
 # main.db:
-#   engine: sqlite:///home/user/.local/share/platypush/main.db
+#   engine: sqlite:////home/user/.local/share/platypush/main.db
 #   # OR, if you want to use e.g. Postgres with the pg8000 driver:
 #   engine: postgresql+pg8000://dbuser:dbpass@dbhost/dbname
+#
+# # NOTE: The short syntax `main.db: <engine_string>` is also supported.
 ###
 
 ### ---------------------

platypush/plugins/redis/__init__.py

@@ -7,6 +7,9 @@ from platypush.utils import get_redis_conf
 class RedisPlugin(Plugin):
     """
     Plugin to send messages on Redis queues.
+
+    See https://redis-py.readthedocs.io/en/latest/connections.html#redis.Redis
+    for supported parameters.
     """
 
     def __init__(self, *args, **kwargs):
@@ -18,24 +21,19 @@ class RedisPlugin(Plugin):
         return Redis(*self.args, **self.kwargs)
 
     @action
-    def send_message(self, queue, msg, *args, **kwargs):
+    def send_message(self, queue: str, msg, *args, **kwargs):
         """
         Send a message to a Redis queue.
 
         :param queue: Queue name
-        :type queue: str
-
         :param msg: Message to be sent
-        :type msg: str, bytes, list, dict, Message object
+        :type msg: str, bytes, list, dict, :class:`platypush.message.Message`
-
-        :param args: Args passed to the Redis constructor (see https://redis-py.readthedocs.io/en/latest/#redis.Redis)
-        :type args: list
 
+        :param args: Args passed to the Redis constructor (see
+            https://redis-py.readthedocs.io/en/latest/connections.html#redis.Redis)
         :param kwargs: Kwargs passed to the Redis constructor (see
-            https://redis-py.readthedocs.io/en/latest/#redis.Redis)
+            https://redis-py.readthedocs.io/en/latest/connections.html#redis.Redis)
-        :type kwargs: dict
         """
-
         if args or kwargs:
             redis = Redis(*args, **kwargs)
         else:
@@ -48,7 +46,6 @@ class RedisPlugin(Plugin):
         """
         :returns: The values specified in keys as a key/value dict (wraps MGET)
         """
-
         return {
             keys[i]: value.decode() if isinstance(value, bytes) else value
             for (i, value) in enumerate(self._get_redis().mget(keys, *args))
@@ -59,7 +56,6 @@ class RedisPlugin(Plugin):
         """
         Set key/values based on mapping (wraps MSET)
         """
-
         try:
             return self._get_redis().mset(**kwargs)
         except TypeError:
@@ -80,7 +76,6 @@ class RedisPlugin(Plugin):
         :param expiration: Expiration timeout (in seconds)
         :type expiration: int
         """
-
         return self._get_redis().expire(key, expiration)
 
     @action
@@ -90,7 +85,6 @@ class RedisPlugin(Plugin):
 
         :param args: Keys to delete
         """
-
         return self._get_redis().delete(*args)