1 files changed, 120 insertions, 0 deletions
diff --git a/src/ansiblelint/schemas/__main__.py b/src/ansiblelint/schemas/__main__.py
new file mode 100644
index 0000000..e3ec8ae
--- /dev/null
+++ b/src/ansiblelint/schemas/__main__.py
@@ -0,0 +1,120 @@
+"""Module containing cached JSON schemas."""
+import json
+import logging
+import os
+import sys
+import time
+import urllib.request
+from collections import defaultdict
+from functools import cache
+from http.client import HTTPException
+from pathlib import Path
+from typing import Any
+from urllib.request import Request
+
+_logger = logging.getLogger(__package__)
+
+# Maps kinds to JSON schemas
+# See https://www.schemastore.org/json/
+store_file = Path(f"{__file__}/../__store__.json").resolve()
+with store_file.open(encoding="utf-8") as json_file:
+    JSON_SCHEMAS = json.load(json_file)
+
+
+class SchemaCacheDict(defaultdict):  # type: ignore[type-arg]
+    """Caching schema store."""
+
+    def __missing__(self, key: str) -> Any:
+        """Load schema on its first use."""
+        value = get_schema(key)
+        self[key] = value
+        return value
+
+
+@cache
+def get_schema(kind: str) -> Any:
+    """Return the schema for the given kind."""
+    schema_file = Path(__file__).parent / f"{kind}.json"
+    with schema_file.open(encoding="utf-8") as f:
+        return json.load(f)
+
+
+_schema_cache = SchemaCacheDict()
+
+
+def refresh_schemas(min_age_seconds: int = 3600 * 24) -> int:
+    """Refresh JSON schemas by downloading latest versions.
+
+    Returns number of changed schemas.
+    """
+    age = int(time.time() - store_file.stat().st_mtime)
+
+    # never check for updated schemas more than once a day
+    if min_age_seconds > age:
+        return 0
+    if not os.access(store_file, os.W_OK):  # pragma: no cover
+        _logger.debug(
+            "Skipping schema update due to lack of writing rights on %s",
+            store_file,
+        )
+        return -1
+    _logger.debug("Checking for updated schemas...")
+
+    changed = 0
+    for kind, data in JSON_SCHEMAS.items():
+        url = data["url"]
+        if "#" in url:
+            msg = f"Schema URLs cannot contain # due to python-jsonschema limitation: {url}"
+            raise RuntimeError(msg)
+        path = Path(__file__).parent.resolve() / f"{kind}.json"
+        _logger.debug("Refreshing %s schema ...", kind)
+        request = Request(url)
+        etag = data.get("etag", "")
+        if etag:
+            request.add_header("If-None-Match", f'"{data.get("etag")}"')
+        try:
+            with urllib.request.urlopen(request, timeout=10) as response:  # noqa: S310
+                if response.status == 200:
+                    content = response.read().decode("utf-8").rstrip()
+                    etag = response.headers["etag"].strip('"')
+                    if etag != data.get("etag", ""):
+                        JSON_SCHEMAS[kind]["etag"] = etag
+                        changed += 1
+                    with path.open("w", encoding="utf-8") as f_out:
+                        _logger.info("Schema %s was updated", kind)
+                        f_out.write(content)
+                        f_out.write("\n")  # prettier/editors
+                        f_out.truncate()
+                        os.fsync(f_out.fileno())
+                        # unload possibly loaded schema
+                        if kind in _schema_cache:  # pragma: no cover
+                            del _schema_cache[kind]
+        except (ConnectionError, OSError, HTTPException) as exc:
+            if (
+                isinstance(exc, urllib.error.HTTPError)
+                and getattr(exc, "code", None) == 304
+            ):
+                _logger.debug("Schema %s is not modified", url)
+                continue
+            # In case of networking issues, we just stop and use last-known good
+            _logger.debug("Skipped schema refresh due to unexpected exception: %s", exc)
+            break
+    if changed:  # pragma: no cover
+        with store_file.open("w", encoding="utf-8") as f_out:
+            # formatting should match our .prettierrc.yaml
+            json.dump(JSON_SCHEMAS, f_out, indent=2, sort_keys=True)
+            f_out.write("\n")  # prettier and editors in general
+        # clear schema cache
+        get_schema.cache_clear()
+    else:
+        store_file.touch()
+        changed = 1
+    return changed
+
+
+if __name__ == "__main__":
+    if refresh_schemas(60 * 10):  # pragma: no cover
+        print("Schemas were updated.")  # noqa: T201
+        sys.exit(1)
+    else:  # pragma: no cover
+        print("Schemas not updated", 0)  # noqa: T201