introduce Configuration and ConfigurationProvider

The Configuration class will help structure the configuration better and will allow us to mock values easier when testing.

The ConfigurationProvider is responsible for providing the same config across the entire app through late binding.

src/pinnwand/app.py

@@ -3,12 +3,17 @@
 
 import tornado.web
 
-from pinnwand import configuration, handler, logger, path
+from pinnwand import handler, logger, path
+from pinnwand.configuration import Configuration, ConfigurationProvider
 
 log = logger.get_logger(__name__)
 
 
 def make_application(debug: bool = False) -> tornado.web.Application:
+    configuration: Configuration = ConfigurationProvider.get_config(
+        load_env=True
+    )
+
     pages: List[Any] = [
         (r"/", handler.website.Create),
         (r"/\+(.*)", handler.website.Create),

src/pinnwand/command.py

@@ -2,17 +2,16 @@
 a HTTP server, add and remove paste, initialize the database and reap expired
 pastes."""
 
-import ast
 import logging
-import os
 import sys
 from datetime import timedelta
-from typing import TYPE_CHECKING, Optional
+from typing import Optional
 
 import click
 import tornado.ioloop
 
 from pinnwand import logger
+from pinnwand.configuration import Configuration, ConfigurationProvider
 from pinnwand.database import models, manager, utils
 
 log = logger.get_logger(__name__)
@@ -30,42 +29,12 @@ def main(verbose: int, configuration_path: Optional[str]) -> None:
     """Pinnwand pastebin software."""
     logging.basicConfig(level=10 + (logging.FATAL - verbose * 10))
 
-    from pinnwand import configuration
-
+    configuration: Configuration = ConfigurationProvider.get_config()
     # First check if we have a configuration path
     if configuration_path:
-        if (
-            TYPE_CHECKING
-        ):  # lie to mypy, see https://github.com/python/mypy/issues/1153
-            import tomllib as toml
-        else:
-            try:
-                import tomllib as toml
-            except ImportError:
-                import tomli as toml
-
-        with open(configuration_path, "rb") as file:
-            configuration_file = toml.load(file)
-
-            for key, value in configuration_file.items():
-                setattr(configuration, key, value)
-
-    # Or perhaps we have configuration in the environment, these are prefixed
-    # with PINNWAND_ and all upper case, remove the prefix, convert to
-    # lowercase.
-    for key, value in os.environ.items():
-        if key.startswith("PINNWAND_"):
-            key = key.removeprefix("PINNWAND_")
-            key = key.lower()
-
-            try:
-                value = ast.literal_eval(value)
-            except (ValueError, SyntaxError):
-                # When `ast.literal_eval` can't parse the value into another
-                # type we take it at string value
-                pass
-
-            setattr(configuration, key, value)
+        configuration.load_config_file(configuration_path)
+
+    configuration.load_environment()
 
     engine = manager.DatabaseManager.get_engine()
     utils.create_tables(engine)
@@ -81,9 +50,11 @@ def main(verbose: int, configuration_path: Optional[str]) -> None:
 )
 def http(port: int, debug: bool) -> None:
     """Run pinnwand's HTTP server."""
-    from pinnwand import configuration, utility
+    from pinnwand import utility
     from pinnwand.app import make_application
 
+    configuration: Configuration = ConfigurationProvider.get_config()
+
     # Reap expired pastes on startup (we might've been shut down for a while)
     utility.reap()
 

src/pinnwand/configuration.py

@@ -1,30 +1,146 @@
-database_uri = "sqlite:///:memory:"
-paste_size = 256 * 1024  # in bytes
-footer = 'View <a href="//github.com/supakeen/pinnwand" target="_BLANK">source code</a>, the <a href="/removal">removal</a> or <a href="/expiry">expiry</a> stories, or read the <a href="/about">about</a> page.'
-paste_help = "<p>Welcome to pinnwand, this site is a pastebin. It allows you to share code with others. If you write code in the text area below and press the paste button you will be given a link you can share with others so they can view your code as well.</p><p>People with the link can view your pasted code, only you can remove your paste and it expires automatically. Note that anyone could guess the URI to your paste so don't rely on it being private.</p>"
-page_path = None
-page_list = ["about", "removal", "expiry"]
-default_selected_lexer = "text"
-preferred_lexers = []  # type: ignore
-logo_path = None
-report_email = None
-expiries = {"1day": 86400, "1week": 604800}
-reaping_periodicity = 1_800_800
-ratelimit = {
-    "read": {
-        "capacity": 100,
-        "consume": 1,
-        "refill": 2,
-    },
-    "create": {
-        "capacity": 2,
-        "consume": 2,
-        "refill": 1,
-    },
-    "delete": {
-        "capacity": 2,
-        "consume": 2,
-        "refill": 1,
-    },
-}
-spamscore = 50
+import ast
+import os
+from typing import Optional, TYPE_CHECKING
+
+if TYPE_CHECKING:  # lie to mypy, see https://github.com/python/mypy/issues/1153
+    import tomllib as toml
+else:
+    try:
+        import tomllib as toml
+    except ImportError:
+        import tomli as toml
+
+
+class Configuration:
+    """A class that holds all pinnwand's configuration."""
+
+    def __init__(self):
+        self._database_uri = "sqlite:///:memory:"
+        self._paste_size = 256 * 1024  # in bytes
+        self._footer = 'View <a href="//github.com/supakeen/pinnwand" target="_BLANK">source code</a>, the <a href="/removal">removal</a> or <a href="/expiry">expiry</a> stories, or read the <a href="/about">about</a> page.'
+        self._paste_help = "<p>Welcome to pinnwand, this site is a pastebin. It allows you to share code with others. If you write code in the text area below and press the paste button you will be given a link you can share with others so they can view your code as well.</p><p>People with the link can view your pasted code, only you can remove your paste and it expires automatically. Note that anyone could guess the URI to your paste so don't rely on it being private.</p>"
+        self._page_path = None
+        self._page_list = ["about", "removal", "expiry"]
+        self._default_selected_lexer = "text"
+        self._preferred_lexers = []  # type: ignore
+        self._logo_path = None
+        self._report_email = None
+        self._expiries = {"1day": 86400, "1week": 604800}
+        self._reaping_periodicity = 1_800_800
+        self._ratelimit = {
+            "read": {
+                "capacity": 100,
+                "consume": 1,
+                "refill": 2,
+            },
+            "create": {
+                "capacity": 2,
+                "consume": 2,
+                "refill": 1,
+            },
+            "delete": {
+                "capacity": 2,
+                "consume": 2,
+                "refill": 1,
+            },
+        }
+        self._spamscore = 50
+
+    # Define getters for each configuration parameter
+    @property
+    def database_uri(self):
+        return self._database_uri
+
+    @property
+    def paste_size(self):
+        return self._paste_size
+
+    @property
+    def footer(self):
+        return self._footer
+
+    @property
+    def paste_help(self):
+        return self._paste_help
+
+    @property
+    def page_path(self):
+        return self._page_path
+
+    @property
+    def page_list(self):
+        return self._page_list
+
+    @property
+    def default_selected_lexer(self):
+        return self._default_selected_lexer
+
+    @property
+    def preferred_lexers(self):
+        return self._preferred_lexers
+
+    @property
+    def logo_path(self):
+        return self._logo_path
+
+    @property
+    def report_email(self):
+        return self._report_email
+
+    @property
+    def expiries(self):
+        return self._expiries
+
+    @property
+    def reaping_periodicity(self):
+        return self._reaping_periodicity
+
+    @property
+    def ratelimit(self):
+        return self._ratelimit
+
+    @property
+    def spamscore(self):
+        return self._spamscore
+
+    def load_config_file(self, path: Optional[str] = None) -> None:
+        """Load configuration settings from a toml file."""
+
+        with open(path, "rb") as file:
+            loaded_configuration = toml.load(file)
+
+            for key, value in loaded_configuration.items():
+                setattr(self, f"_{key}", value)
+
+    def load_environment(self):
+        """Load configuration from the environment, if any."""
+        for key, value in os.environ.items():
+            if not key.startswith("PINNWAND_"):
+                continue
+
+            key = key.removeprefix("PINNWAND_")
+            key = key.lower()
+
+            try:
+                value = ast.literal_eval(value)
+                setattr(self, f"_{key}", value)
+            except (ValueError, SyntaxError):
+                # When `ast.literal_eval` can't parse the value into another
+                # type we take it at string value
+                pass
+
+
+class ConfigurationProvider:
+    """A class responsible for providing an instance of the configuration on demand."""
+
+    _config: Configuration = None
+
+    @classmethod
+    def get_config(cls, load_env=False):
+        """Return the loaded configuration."""
+        if not cls._config:
+            cls._config = Configuration()
+            if load_env:
+                cls._config.load_environment()
+
+        return cls._config

src/pinnwand/database/manager.py

@@ -5,7 +5,7 @@
 from sqlalchemy.orm.session import Session
 
 
-from pinnwand import configuration
+from pinnwand.configuration import Configuration, ConfigurationProvider
 
 
 class DatabaseManager:
@@ -17,7 +17,7 @@ class DatabaseManager:
     @classmethod
     def get_engine(cls):
         """Return an engine for the currently configured connection string."""
-
+        configuration: Configuration = ConfigurationProvider.get_config()
         if not cls._engine:
             cls._engine = create_engine(configuration.database_uri)
 

src/pinnwand/database/models.py

@@ -18,7 +18,8 @@
     relationship,
 )
 
-from pinnwand import configuration, defensive, error, logger, utility
+from pinnwand import defensive, error, logger, utility
+from pinnwand.configuration import Configuration, ConfigurationProvider
 
 
 log = logger.get_logger(__name__)
@@ -102,6 +103,8 @@ def __init__(
         if not len(raw):
             raise error.ValidationError("Empty pastes are not allowed")
 
+        configuration: Configuration = ConfigurationProvider.get_config()
+
         if len(raw) > configuration.paste_size:
             raise error.ValidationError(
                 f"Text exceeds size limit {configuration.paste_size//1024} (kB)"

src/pinnwand/defensive.py

@@ -5,7 +5,8 @@
 import token_bucket
 from tornado.httputil import HTTPServerRequest
 
-from pinnwand import configuration, logger
+from pinnwand import logger
+from pinnwand.configuration import Configuration, ConfigurationProvider
 
 log = logger.get_logger(__name__)
 
@@ -30,6 +31,8 @@ def ratelimit(request: HTTPServerRequest, area: str = "global") -> bool:
     ranges usually belong to the same person. If this is encountered in real
     life this function will have to be expanded."""
 
+    configuration: Configuration = ConfigurationProvider.get_config()
+
     if area not in ratelimit_area:
         ratelimit_area[area] = {}
 

src/pinnwand/handler/api_curl.py

@@ -2,7 +2,8 @@
 
 import tornado.web
 
-from pinnwand import configuration, defensive, logger, utility
+from pinnwand import defensive, logger, utility
+from pinnwand.configuration import Configuration, ConfigurationProvider
 from pinnwand.database import models, manager
 
 log = logger.get_logger(__name__)
@@ -21,6 +22,7 @@ def post(self) -> None:
             self.write("Enhance your calm, you have exceeded the ratelimit.")
             return
 
+        configuration: Configuration = ConfigurationProvider.get_config()
         lexer = self.get_body_argument("lexer", "text")
         raw = self.get_body_argument("raw", "", strip=False)
         expiry = self.get_body_argument("expiry", "1day")

src/pinnwand/handler/api_deprecated.py

@@ -7,7 +7,8 @@
 import tornado.web
 from tornado.escape import url_escape
 
-from pinnwand import configuration, defensive, error, logger, utility
+from pinnwand import defensive, error, logger, utility
+from pinnwand.configuration import Configuration, ConfigurationProvider
 from pinnwand.database import models, manager
 
 log = logger.get_logger(__name__)
@@ -124,6 +125,8 @@ async def post(self) -> None:
         if defensive.ratelimit(self.request, area="create"):
             raise error.RatelimitError()
 
+        configuration: Configuration = ConfigurationProvider.get_config()
+
         lexer = self.get_body_argument("lexer")
         raw = self.get_body_argument("code", strip=False)
         expiry = self.get_body_argument("expiry")
@@ -222,6 +225,8 @@ async def get(self) -> None:
         if defensive.ratelimit(self.request, area="read"):
             raise error.RatelimitError()
 
+        configuration: Configuration = ConfigurationProvider.get_config()
+
         self.write(
             {
                 name: str(timedelta(seconds=delta))