feat: use a local static cache for commonly used contexts

Signed-off-by: Clément Humbert <clement.humbert@sicpa.com>

MANIFEST.in

@@ -1,5 +1,11 @@
 include aries_cloudagent/config/default_logging_config.ini
 include aries_cloudagent/commands/default_version_upgrade_config.yml
+include aries_cloudagent/vc/ld_proofs/resources/credentials_context.jsonld
+include aries_cloudagent/vc/ld_proofs/resources/did_documents_context.jsonld
+include aries_cloudagent/vc/ld_proofs/resources/status_list_context.jsonld
+include aries_cloudagent/vc/ld_proofs/resources/security-v1-context.jsonld
+include aries_cloudagent/vc/ld_proofs/resources/security-v2-context.jsonld
+include aries_cloudagent/vc/ld_proofs/resources/ed25519-2020-context.jsonld
 include requirements.txt
 include requirements.dev.txt
 include requirements.indy.txt

aries_cloudagent/vc/ld_proofs/document_downloader.py

@@ -0,0 +1,186 @@
+"""Quick and dirty fix to use as alternative to pyld downloader.
+
+Allows keeping some context in local filesystem.
+"""
+import logging
+import re
+import string
+from typing import Dict, Optional
+import urllib.parse as urllib_parse
+import importlib
+
+import requests
+from pyld import jsonld
+from pyld.jsonld import JsonLdError, parse_link_header, LINK_HEADER_REL
+
+logger = logging.getLogger(__name__)
+
+
+def _load_jsonld_file(
+    original_url, filename: str, resource_path: str = f"{__package__}.resources"
+):
+    """Load context from package.
+
+    Given a URL and filename,
+    load a context in the format used by pyld document loader.
+    """
+    return {
+        "contentType": "application/ld+json",
+        "contextUrl": None,
+        "documentUrl": original_url,
+        "document": (importlib.resources.files(resource_path) / filename).read_text(),
+    }
+
+
+class StaticCacheJsonLdDownloader:
+    """Context downloader with filesystem static cache for common contexts."""
+
+    CONTEXT_FILE_MAPPING = {
+        "https://www.w3.org/2018/credentials/v1": "credentials_context.jsonld",
+        "https://w3id.org/vc/status-list/2021/v1": "status_list_context.jsonld",
+        "https://www.w3.org/ns/did/v1": "did_documents_context.jsonld",
+        "https://w3id.org/security/v1": "security-v1-context.jsonld",
+        "https://w3id.org/security/v2": "security-v2-context.jsonld",
+        "https://w3id.org/security/suites/ed25519-2020/v1": "ed25519-2020-context.jsonld",
+    }
+
+    def __init__(self, document_downloader=None, document_parser=None):
+        """Load static document on initialization."""
+        self.documents_downloader = document_downloader or JsonLdDocumentDownloader()
+        self.document_parser = document_parser or JsonLdDocumentParser()
+
+        self.cache = {
+            url: self.document_parser.parse(_load_jsonld_file(url, filename), None)
+            for url, filename in StaticCacheJsonLdDownloader.CONTEXT_FILE_MAPPING.items()
+        }
+
+    def load(self, url, options=None):
+        """Load a jsonld document from URL.
+
+        Prioritize local static cache before attempting to download from the URL.
+        """
+        cached = self.cache.get(url)
+
+        if cached is not None:
+            logger.info("Local cache hit for context: %s", url)
+            return cached
+
+        logger.debug("Context %s not in static cache, resolving from URL.", url)
+        return self._live_load(url, options)
+
+    def _live_load(self, url, options=None):
+        doc, link_header = self.documents_downloader.download(url, options)
+        return self.document_parser.parse(doc, link_header)
+
+
+class JsonLdDocumentDownloader:
+    """JsonLd documents downloader."""
+
+    def download(self, url: str, options: Dict, **kwargs):
+        """Retrieves JSON-LD at the given URL.
+
+        This was lifted from pyld.documentloader.requests.
+
+        :param url: the URL to retrieve.
+        :param options:
+
+        :return: the RemoteDocument.
+
+        """
+        options = options or {}
+
+        try:
+            # validate URL
+            pieces = urllib_parse.urlparse(url)
+            if (
+                not all([pieces.scheme, pieces.netloc])
+                or pieces.scheme not in ["http", "https"]
+                or set(pieces.netloc)
+                > set(string.ascii_letters + string.digits + "-.:")
+            ):
+                raise JsonLdError(
+                    'URL could not be dereferenced; only "http" and "https" '
+                    "URLs are supported.",
+                    "jsonld.InvalidUrl",
+                    {"url": url},
+                    code="loading document failed",
+                )
+            if options.get("secure") and pieces.scheme != "https":
+                raise JsonLdError(
+                    "URL could not be dereferenced; secure mode enabled and "
+                    'the URL\'s scheme is not "https".',
+                    "jsonld.InvalidUrl",
+                    {"url": url},
+                    code="loading document failed",
+                )
+            headers = options.get("headers")
+            if headers is None:
+                headers = {"Accept": "application/ld+json, application/json"}
+            response = requests.get(url, headers=headers, **kwargs)
+
+            content_type = response.headers.get("content-type")
+            if not content_type:
+                content_type = "application/octet-stream"
+            doc = {
+                "contentType": content_type,
+                "contextUrl": None,
+                "documentUrl": response.url,
+                "document": response.json(),
+            }
+
+            return doc, response.headers.get("link")
+        except Exception as cause:
+            raise JsonLdError(
+                "Could not retrieve a JSON-LD document from the URL.",
+                "jsonld.LoadDocumentError",
+                code="loading document failed",
+                cause=cause,
+            )
+
+
+class JsonLdDocumentParser:
+    """JsonLd documents parser."""
+
+    def parse(self, doc: Dict, link_header: Optional[str]):
+        """Parse a jsonld document after retrieval.
+
+        This was lifted from pyld.documentloader.requests.
+        """
+        try:
+            if link_header:
+                linked_context = parse_link_header(link_header).get(LINK_HEADER_REL)
+                # only 1 related link header permitted
+                if linked_context and doc["content_type"] != "application/ld+json":
+                    if isinstance(linked_context, list):
+                        raise JsonLdError(
+                            "URL could not be dereferenced, "
+                            "it has more than one "
+                            "associated HTTP Link Header.",
+                            "jsonld.LoadDocumentError",
+                            {"url": doc["url"]},
+                            code="multiple context link headers",
+                        )
+                    doc["contextUrl"] = linked_context["target"]
+                linked_alternate = parse_link_header(link_header).get("alternate")
+                # if not JSON-LD, alternate may point there
+                if (
+                    linked_alternate
+                    and linked_alternate.get("type") == "application/ld+json"
+                    and not re.match(
+                        r"^application\/(\w*\+)?json$", doc["content_type"]
+                    )
+                ):
+                    doc["contentType"] = "application/ld+json"
+                    doc["documentUrl"] = jsonld.prepend_base(
+                        doc["url"], linked_alternate["target"]
+                    )
+            return doc
+        except JsonLdError as e:
+            raise e
+        except Exception as cause:
+            raise JsonLdError(
+                "Could not retrieve a JSON-LD document from the URL.",
+                "jsonld.LoadDocumentError",
+                code="loading document failed",
+                cause=cause,
+            )

aries_cloudagent/vc/ld_proofs/document_loader.py

@@ -8,6 +8,7 @@
 from pydid.did_url import DIDUrl
 from pyld.documentloader import requests
 
+from .document_downloader import StaticCacheJsonLdDownloader
 from ...cache.base import BaseCache
 from ...core.profile import Profile
 from ...resolver.did_resolver import DIDResolver
@@ -33,7 +34,8 @@ def __init__(self, profile: Profile, cache_ttl: int = 300) -> None:
         self.profile = profile
         self.resolver = profile.inject(DIDResolver)
         self.cache = profile.inject_or(BaseCache)
-        self.requests_loader = requests.requests_document_loader()
+        self.online_request_loader = requests.requests_document_loader()
+        self.requests_loader = StaticCacheJsonLdDownloader().load
         self.executor = concurrent.futures.ThreadPoolExecutor(max_workers=1)
         self.cache_ttl = cache_ttl
         self._event_loop = asyncio.get_event_loop()