Http API to access the SWH vault

This API currently only concern the directories as it uses the first draft of the cooker.

Ref swh-vault#532 (closed) Depends on !36 (closed)

---

Migrated from D108 (view on Phabricator)

swh/storage/vault/api/client.py

+# Copyright (C) 2016  The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+import pickle
+import requests
+
+from swh.core import hashutil
+from swh.storage.exc import StorageAPIError
+from swh.objstorage.api.common import (decode_response,
+                                       encode_data_client as encode_data)
+
+
+class RemoteVaultCache():
+    """Client to the Software Heritage vault cache."""
+
+    def __init__(self, base_url):
+        self.base_url = base_url if base_url.endswith('/') else base_url + '/'
+        self.session = requests.Session()
+
+    def url(self, endpoint):
+        return'%s%s' % (self.base_url, endpoint)
+
+    def post(self, endpoint, data):
+        try:
+            response = self.session.post(
+                self.url(endpoint),
+                data=encode_data(data),
+                headers={'content-type': 'application/x-msgpack'},
+            )
+        except ConnectionError as e:
+            print(str(e))
+            raise StorageAPIError(e)
+
+        # XXX: this breaks language-independence and should be
+        # replaced by proper unserialization
+        if response.status_code == 400:
+            raise pickle.loads(decode_response(response))
+
+        return decode_response(response)
+
+    def get(self, endpoint, data=None):
+        try:
+            response = self.session.get(
+                self.url(endpoint),
+                params=data,
+            )
+        except ConnectionError as e:
+            print(str(e))
+            raise StorageAPIError(e)
+
+        if response.status_code == 404:
+            return None
+
+        # XXX: this breaks language-independence and should be
+        # replaced by proper unserialization
+        if response.status_code == 400:
+            raise pickle.loads(decode_response(response))
+        else:
+            return decode_response(response)
+
+    def directory_ls(self):
+        return self.get('vault/directory/')
+
+    def directory_get(self, obj_id):
+        return self.get('vault/directory/%s/' % (hashutil.hash_to_hex(obj_id)))
+
+    def directory_cook(self, obj_id):
+        return self.post('vault/directory/%s/' % hashutil.hash_to_hex(obj_id),
+                         data={})