Pass CLI config to the app as JSON in PAGERITE_CONFIG

pagerite/config.py

@@ -0,0 +1,28 @@
+"""CLI → app configuration, passed as JSON in the ``PAGERITE_CONFIG`` env var.
+
+Kept dependency-free (msgspec only) so ``__main__`` can build and serialize
+the config before any app module is imported, and the app side parses the
+same struct back.  Import-time safe: nothing here reads the environment
+until ``load()`` is called.
+"""
+
+import os
+
+import msgspec
+
+
+class Config(msgspec.Struct):
+    """Configuration passed from the CLI entry point to the app."""
+
+    #: Public hostname of the site; names the per-site data directory
+    #: ``<hostname>/{content.kantadb, analytics.json, files}`` under the cwd.
+    hostname: str = "localhost"
+    #: Download/update the DB-IP city lite database at startup (--dbip).
+    dbip: bool = False
+
+
+def load() -> Config:
+    """Parse ``PAGERITE_CONFIG``, or the defaults when unset."""
+    if raw := os.getenv("PAGERITE_CONFIG"):
+        return msgspec.json.decode(raw.encode(), type=Config)
+    return Config()