Write nginx-compatible map file for redirects

content/nested/sibling.md

@@ -1 +1,6 @@
+---
+redirects:
+    - /sibling
+---
+
 # Sibling

hooks/redirects.py

@@ -0,0 +1,34 @@
+from mkdocs.structure.pages import Page
+from mkdocs.structure.files import Files
+from mkdocs.exceptions import PluginError
+import os
+from mkdocs.utils import write_file
+
+REDIRECTS = dict()
+
+def on_pre_build(config):
+    REDIRECTS.clear()
+
+def on_page_markdown(markdown, page: Page, config, files: Files):
+    if not (redirects := page.meta.get("redirects")):
+        return
+
+    for redirect in redirects:
+        if files.get_file_from_path(redirect):
+            raise PluginError(f"Cannnot redirect to {page.url}, source {redirect} already exists")
+
+        if redirect in REDIRECTS:
+            raise PluginError(f"Redirect from {redirect} already exists: {REDIRECTS[redirect]}")
+
+        REDIRECTS[redirect] = f"/{page.url}"
+
+
+def on_post_build(config):
+    redirect_file = os.path.join(config["site_dir"], ".config", "redirects.txt")
+
+    redirects = "\n".join(
+        f"{src}\t{dest};"
+        for src, dest in REDIRECTS.items()
+    )
+
+    write_file(redirects.encode(), redirect_file)

mkdocs.yml

@@ -14,6 +14,7 @@ hooks:
   - hooks/images.py
   - hooks/page-render.py
   - hooks/static.py
+  - hooks/redirects.py
 
 markdown_extensions:
   - attr_list