feat: make index file patterns configurable per remote

Replace hardcoded is_index_file logic with regex patterns driven by
remotes.yaml. Package-level defaults (alpine/rpm/docker) are merged with
any extra patterns listed under index_patterns in the remote config.

src/artifactapi/cache.py

@@ -1,3 +1,4 @@
+import re
 import time
 import hashlib
 import redis
@@ -17,27 +18,11 @@ class RedisCache:
             self.client = None
             self.available = False
 
-    def is_index_file(self, file_path: str) -> bool:
-        """Check if the file is an index file that should have TTL"""
-        return (
-            file_path.endswith("APKINDEX.tar.gz")
-            or file_path.endswith("Packages.gz")
-            or file_path.endswith("repomd.xml")
-            or ("repodata/" in file_path
-                and file_path.endswith((
-                    ".xml", ".xml.gz", ".xml.bz2", ".xml.xz", ".xml.zck", ".xml.zst",
-                    ".sqlite", ".sqlite.gz", ".sqlite.bz2", ".sqlite.xz", ".sqlite.zck", ".sqlite.zst",
-                    ".yaml.xz", ".yaml.gz", ".yaml.bz2", ".yaml.zst",
-                    ".asc", ".txt"
-                )))
-            # Docker tag-based manifests are mutable (index); digest-pinned are immutable (file)
-            or (
-                "/manifests/" in file_path
-                and not file_path.split("/manifests/", 1)[1].startswith("sha256:")
-            )
-            or "/tags/list" in file_path
-            or file_path.endswith("/tags/list")
-        )
+    def is_index_file(self, file_path: str, patterns: list[str] | None = None) -> bool:
+        """Return True if file_path matches any of the index patterns."""
+        if patterns is None:
+            patterns = []
+        return any(re.search(p, file_path) for p in patterns)
 
     def get_index_cache_key(self, remote_name: str, path: str) -> str:
         """Generate cache key for index files"""

src/artifactapi/config.py

@@ -4,6 +4,25 @@ import yaml
 from typing import Optional
 
 
+_PACKAGE_INDEX_PATTERNS: dict[str, list[str]] = {
+    "alpine": [
+        r"APKINDEX\.tar\.gz$",
+    ],
+    "rpm": [
+        r"repomd\.xml$",
+        r"repodata/.*\.(xml|xml\.gz|xml\.bz2|xml\.xz|xml\.zck|xml\.zst"
+        r"|sqlite|sqlite\.gz|sqlite\.bz2|sqlite\.xz|sqlite\.zck|sqlite\.zst"
+        r"|yaml\.xz|yaml\.gz|yaml\.bz2|yaml\.zst|asc|txt)$",
+        r"Packages\.gz$",
+    ],
+    "docker": [
+        r"/manifests/(?!sha256:)[^/]+$",
+        r"/tags/list$",
+    ],
+    "generic": [],
+}
+
+
 class ConfigManager:
     def __init__(self, config_file: str = "remotes.yaml"):
         self.config_file = config_file
@@ -111,6 +130,20 @@ class ConfigManager:
         db_url = f"postgresql://{db_user}:{db_pass}@{db_host}:{db_port}/{db_name}"
         return {"url": db_url}
 
+    def get_index_patterns(self, remote_name: str) -> list[str]:
+        """Return index-file patterns for a remote.
+
+        Merges the package-level defaults with any extra patterns listed under
+        ``index_patterns`` in the remote's config.
+        """
+        remote_config = self.get_remote_config(remote_name)
+        if not remote_config:
+            return []
+        package = remote_config.get("package", "generic")
+        defaults = _PACKAGE_INDEX_PATTERNS.get(package, [])
+        extra = remote_config.get("index_patterns", [])
+        return defaults + [p for p in extra if p not in defaults]
+
     def get_cache_config(self, remote_name: str) -> dict:
         """Get cache configuration for a specific remote"""
         remote_config = self.get_remote_config(remote_name)

src/artifactapi/main.py

@@ -179,7 +179,8 @@ async def check_artifact_patterns(
     remote_name: str, repo_path: str, file_path: str, full_path: str
 ) -> bool:
     # First check if this is an index file - always allow index files
-    if cache.is_index_file(file_path) or cache.is_index_file(full_path):
+    index_patterns = config.get_index_patterns(remote_name)
+    if cache.is_index_file(file_path, index_patterns) or cache.is_index_file(full_path, index_patterns):
         return True
 
     # Then check basic include patterns
@@ -319,7 +320,7 @@ async def get_artifact(remote_name: str, path: str):
 
     # For index files, check Redis TTL validity
     filename = os.path.basename(path)
-    is_index = cache.is_index_file(path)  # Check full path, not just filename
+    is_index = cache.is_index_file(path, config.get_index_patterns(remote_name))
 
     if cached_key and is_index:
         # Index file exists, but check if it's still valid
@@ -467,7 +468,7 @@ async def docker_v2_proxy(request: Request, remote_name: str, path: str):
     if not storage.exists(cached_key):
         cached_key = None
 
-    is_index = cache.is_index_file(path)
+    is_index = cache.is_index_file(path, config.get_index_patterns(remote_name))
 
     if cached_key and is_index:
         if not cache.is_index_valid(remote_name, path):