feat(scheduler): Scheduler is now a plugin

Scheduler allows to schedule tasks, like cron does, but requires special configuration.

flaschengeist/config.py

@@ -77,6 +77,7 @@ def configure_app(app, test_config=None):
             "auth": {"enabled": True},
             "roles": {"enabled": True},
             "users": {"enabled": True},
+            "scheduler": {"enabled": True},
         },
     )
 

flaschengeist/flaschengeist.toml

@@ -11,7 +11,11 @@ root = "/api"
 # Set secret key
 secret_key = "V3ryS3cr3t"
 # Domain used by frontend
-#domain = "flaschengeist.local"
+
+[scheduler]
+# Possible values are: "passive_web" (default), "active_web" and "system"
+# See documentation
+# cron = "passive_web"
 
 [LOGGING]
 # You can override all settings from the logging.toml here

flaschengeist/plugins/scheduler.py

@@ -0,0 +1,83 @@
+import pkg_resources
+from datetime import datetime, timedelta
+from flask import Blueprint
+
+from flaschengeist import logger
+from flaschengeist.utils.HTTP import no_content
+
+from . import Plugin
+
+
+class __Task:
+    def __init__(self, function, **kwags):
+        self.function = function
+        self.interval = timedelta(**kwags)
+
+
+_scheduled_tasks: dict[__Task] = dict()
+
+
+def scheduled(id: str, replace=False, **kwargs):
+    """
+    kwargs: days, hours, minutes
+    """
+
+    def real_decorator(function):
+        if id not in _scheduled_tasks or replace:
+            logger.info(f"Registered task: {id}")
+            _scheduled_tasks[id] = __Task(function, **kwargs)
+        else:
+            logger.debug(f"Skipping already registered task: {id}")
+        return function
+
+    return real_decorator
+
+
+class SchedulerPlugin(Plugin):
+    id = "dev.flaschengeist.scheduler"
+    name = "scheduler"
+    blueprint = Blueprint(name, __name__)
+
+    def __init__(self, config=None):
+        """Constructor called by create_app
+        Args:
+            config: Dict configuration containing the plugin section
+        """
+
+        def __view_func():
+            self.run_tasks()
+            return no_content()
+
+        def __passiv_func(v):
+            try:
+                self.run_tasks()
+            except:
+                logger.error("Error while executing scheduled tasks!", exc_info=True)
+
+        self.version = pkg_resources.get_distribution(self.__module__.split(".")[0]).version
+        cron = None if config is None else config.get("cron", "passive_web").lower()
+
+        if cron is None or cron == "passive_web":
+            self.blueprint.teardown_app_request(__passiv_func)
+        elif cron == "active_web":
+            self.blueprint.add_url_rule("/cron", view_func=__view_func)
+
+    def run_tasks(self):
+        changed = False
+        now = datetime.now()
+        status = self.get_setting("status", default=dict())
+
+        for id, task in _scheduled_tasks.items():
+            last_run = status.setdefault(id, now)
+            if last_run + task.interval <= now:
+                logger.debug(
+                    f"Run task {id}, was scheduled for {last_run + task.interval}, next iteration: {now + task.interval}"
+                )
+                task.function()
+                changed = True
+        if changed:
+            # Remove not registered tasks
+            for id in status.keys():
+                if id not in _scheduled_tasks.keys():
+                    del status[id]
+            self.set_setting("status", status)

flaschengeist/utils/scheduler.py

@@ -1,17 +0,0 @@
-from flask import current_app
-
-from flaschengeist.utils.HTTP import no_content
-
-_scheduled = set()
-
-
-def scheduled(func):
-    _scheduled.add(func)
-    return func
-
-
-@current_app.route("/cron")
-def __run_scheduled():
-    for function in _scheduled:
-        function()
-    return no_content()

readme.md

@@ -39,6 +39,19 @@ Configuration is done within the a `flaschengeist.toml`file, you can copy the on
 
 Uncomment and change at least all the database parameters!
 
+#### CRON
+Some functionality used by some plugins rely on regular updates,
+but as flaschengeists works as an WSGI app it can not controll when it gets called.
+
+So you have to configure one of the following options to call flaschengeists CRON tasks:
+
+1. Passive Web-CRON: Every time an users calls flaschengeist a task is scheduled (**NOT RECOMMENDED**)
+  - Pros: No external configuration needed
+  - Cons: Slower user experience, no guaranteed execution time of tasks
+2. Active Web-CRON: You configure a webworker to call `<flaschengeist>/cron`
+  - Pros: Guaranteed execution interval, no impact on user experience (at least if you do not limit wsgi worker threads)
+  - Cons: Uses one of the webserver threads while executing
+
 ### Database installation
 The user needs to have full permissions to the database.
 If not you need to create user and database manually do (or similar on Windows):

setup.py

@@ -68,6 +68,7 @@ setup(
             "balance = flaschengeist.plugins.balance:BalancePlugin",
             "mail = flaschengeist.plugins.message_mail:MailMessagePlugin",
             "pricelist = flaschengeist.plugins.pricelist:PriceListPlugin",
+            "scheduler = flaschengeist.plugins.scheduler:SchedulerPlugin",
         ],
     },
     cmdclass={