Coverage for /builds/BuildGrid/buildgrid/buildgrid/server/actioncache/caches/s3_cache.py: 92.98%
114 statements
« prev ^ index » next coverage.py v7.4.1, created at 2025-05-28 16:48 +0000
« prev ^ index » next coverage.py v7.4.1, created at 2025-05-28 16:48 +0000
1# Copyright (C) 2019 Bloomberg LP
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7# <http://www.apache.org/licenses/LICENSE-2.0>
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
16"""
17S3 Action Cache
18==================
20Implements an Action Cache using S3 to store cache entries.
22"""
24import io
25import logging
26from typing import Any
28import boto3
29from botocore.config import Config as BotoConfig
30from botocore.exceptions import ClientError
32from buildgrid._protos.build.bazel.remote.execution.v2.remote_execution_pb2 import ActionResult, Digest
33from buildgrid.server.actioncache.caches.action_cache_abc import ActionCacheABC
34from buildgrid.server.cas.storage.storage_abc import StorageABC
35from buildgrid.server.enums import ActionCacheEntryType
36from buildgrid.server.exceptions import NotFoundError, StorageFullError
37from buildgrid.server.logging import buildgrid_logger
38from buildgrid.server.s3 import s3utils
40LOGGER = buildgrid_logger(__name__)
43class S3ActionCache(ActionCacheABC):
44 def __init__(
45 self,
46 storage: StorageABC,
47 allow_updates: bool = True,
48 cache_failed_actions: bool = True,
49 entry_type: ActionCacheEntryType | None = ActionCacheEntryType.ACTION_RESULT_DIGEST,
50 migrate_entries: bool | None = False,
51 bucket: str | None = None,
52 endpoint_url: str | None = None,
53 aws_access_key_id: str | None = None,
54 aws_secret_access_key: str | None = None,
55 config: BotoConfig | None = BotoConfig(),
56 cache_key_salt: str | None = None,
57 ):
58 """Initialises a new ActionCache instance using S3 to persist the action cache.
60 Args:
61 storage (StorageABC): storage backend instance to be used to store ActionResults.
62 allow_updates (bool): allow the client to write to storage
63 cache_failed_actions (bool): whether to store failed actions in the Action Cache
64 entry_type (ActionCacheEntryType): whether to store ActionResults or their digests.
65 migrate_entries (bool): if set, migrate entries that contain a value with
66 a different `EntryType` to `entry_type` as they are accessed
67 (False by default).
68 cache_key_salt (str): if provided, included in the S3 key for cache entries. Use
69 to isolate or share specific chunks of a shared set of S3 buckets.
71 bucket (str): Name of bucket
72 endpoint_url (str): URL of endpoint.
73 aws_access_key_id (str): S3-ACCESS-KEY
74 aws_secret_access_key (str): S3-SECRET-KEY
75 """
76 super().__init__(storage=storage, allow_updates=allow_updates)
78 self._entry_type = entry_type
79 self._migrate_entries = migrate_entries
81 self._cache_failed_actions = cache_failed_actions
82 self._cache_key_salt = cache_key_salt
83 assert bucket is not None
84 self._bucket_template = bucket
86 # Boto logs can be very verbose, restrict to WARNING
87 for boto_logger_name in ["boto3", "botocore", "s3transfer", "urllib3"]:
88 boto_logger = logging.getLogger(boto_logger_name)
89 boto_logger.setLevel(max(boto_logger.level, logging.WARNING))
91 # Only pass arguments with a value to support testing with moto_server
92 client_kwargs: dict[str, Any] = {}
93 if endpoint_url is not None:
94 client_kwargs["endpoint_url"] = endpoint_url
95 if aws_access_key_id is not None:
96 client_kwargs["aws_access_key_id"] = aws_access_key_id
97 if aws_secret_access_key is not None:
98 client_kwargs["aws_secret_access_key"] = aws_secret_access_key
99 client_kwargs["config"] = config
101 self._s3cache = boto3.client("s3", **client_kwargs)
103 # --- Public API ---
104 @property
105 def allow_updates(self) -> bool:
106 return self._allow_updates
108 def get_action_result(self, action_digest: Digest) -> ActionResult:
109 """Retrieves the cached ActionResult for the given Action digest.
111 Args:
112 action_digest: The digest to get the result for
114 Returns:
115 The cached ActionResult matching the given key or raises
116 NotFoundError.
117 """
118 action_result = self._get_action_result(action_digest)
119 if action_result is not None:
120 if self.referenced_blobs_still_exist(action_digest, action_result):
121 return action_result
123 if self._allow_updates:
124 LOGGER.debug(
125 "Removing action from cache due to missing blobs in CAS.",
126 tags=dict(digest=action_digest),
127 )
128 self._delete_key_from_cache(action_digest)
130 raise NotFoundError(f"Key not found: {action_digest.hash}/{action_digest.size_bytes}")
132 def update_action_result(self, action_digest: Digest, action_result: ActionResult) -> None:
133 """Stores the result in cache for the given key.
135 Args:
136 action_digest (Digest): digest of Action to update
137 action_result (ActionResult): ActionResult to store.
138 """
139 if not self._allow_updates:
140 raise NotImplementedError("Updating cache not allowed")
142 if self._cache_failed_actions or action_result.exit_code == 0:
143 assert self._storage, "Storage used before initialization"
144 action_result_digest = self._storage.put_message(action_result)
146 if self._entry_type == ActionCacheEntryType.ACTION_RESULT_DIGEST:
147 self._update_cache_key(action_digest, action_result_digest.SerializeToString())
148 else:
149 self._update_cache_key(action_digest, action_result.SerializeToString())
151 LOGGER.info("Result cached for action.", tags=dict(digest=action_digest))
153 # --- Private API ---
154 def _get_action_result(self, digest: Digest) -> ActionResult | None:
155 """Get an `ActionResult` from the cache.
157 If present, returns the `ActionResult` corresponding to the given digest.
158 Otherwise returns None.
160 When configured to do so, if the value stored in the entry in S3 contains
161 a different type, it will convert it to `entry_type`.
163 Args:
164 digest: Action digest to get the associated ActionResult digest for
166 Returns:
167 The `ActionResult` or None if the digest is not present
168 """
169 value_in_cache = self._get_value_from_cache(digest)
170 if not value_in_cache:
171 return None
173 # Attempting to parse the entry as a `Digest` first:
174 action_result_digest = Digest.FromString(value_in_cache)
175 if len(action_result_digest.hash) == len(digest.hash):
176 # The cache contains the `Digest` of the `ActionResult`:
177 assert self._storage, "Storage used before initialization"
178 action_result = self._storage.get_message(action_result_digest, ActionResult)
180 # If configured, update the entry to contain an `ActionResult`:
181 if self._entry_type == ActionCacheEntryType.ACTION_RESULT and self._migrate_entries:
182 LOGGER.debug("Converting entry from Digest to ActionResult.", tags=dict(digest=digest))
183 assert action_result, "Returned result was none"
184 self._update_cache_key(digest, action_result.SerializeToString())
186 else:
187 action_result = ActionResult.FromString(value_in_cache)
189 # If configured, update the entry to contain a `Digest`:
190 if self._entry_type == ActionCacheEntryType.ACTION_RESULT_DIGEST and self._migrate_entries:
191 LOGGER.debug("Converting entry from ActionResult to Digest.", tags=dict(digest=digest))
192 assert self._storage, "Storage used before initialization"
193 action_result_digest = self._storage.put_message(action_result)
194 self._update_cache_key(digest, action_result_digest.SerializeToString())
196 return action_result
198 def _get_value_from_cache(self, digest: Digest) -> bytes | None:
199 """Get the bytes stored in cache for the given Digest.
201 Args:
202 digest: Action digest to get the associated bytes in S3
204 Returns:
205 bytes or None if the digest is not present
206 """
208 try:
209 s3object = self._get_s3object(digest)
210 s3object.fileobj = io.BytesIO()
211 s3utils.get_object(self._s3cache, s3object)
212 s3object.fileobj.seek(0)
213 return s3object.fileobj.read()
214 except ClientError as e:
215 if e.response["Error"]["Code"] not in ["404", "NoSuchKey"]:
216 raise
217 return None
219 def _update_cache_key(self, digest: Digest, value: bytes) -> None:
220 try:
221 s3object = self._get_s3object(digest)
222 s3object.fileobj = io.BytesIO(value)
223 s3object.filesize = len(value)
224 s3utils.put_object(self._s3cache, s3object)
225 except ClientError as error:
226 if error.response["Error"]["Code"] == "QuotaExceededException":
227 raise StorageFullError("ActionCache S3 Quota Exceeded.") from error
228 raise error
230 def _delete_key_from_cache(self, digest: Digest) -> None:
231 """Remove an entry from the ActionCache
233 Args:
234 digest: entry to remove from the ActionCache
236 Returns:
237 None
238 """
239 if not self._allow_updates:
240 raise NotImplementedError("Updating cache not allowed")
242 self._s3cache.delete_object(Bucket=self._get_bucket_name(digest), Key=self._get_key(digest))
244 def _get_key(self, digest: Digest) -> str:
245 """
246 Given a `Digest`, returns the key used to store its
247 corresponding entry in S3.
248 """
249 if self._cache_key_salt is None:
250 return f"{digest.hash}_{digest.size_bytes}"
251 return f"{self._cache_key_salt}_{digest.hash}_{digest.size_bytes}"
253 def _get_bucket_name(self, digest: Digest) -> str:
254 """Return the formatted bucket name for a given digest.
256 This formats the bucket template defined in the configuration file
257 using a digest to be stored in the cache. This allows the cache
258 contents to be sharded across multiple S3 buckets, allowing us to
259 cache more Actions than can be stored in a single S3 bucket.
261 Currently the only variable interpolated into the template is
262 ``digest``, which contains the hash part of the Digest. A template
263 string which includes undefined variables will result in a
264 non-functional ActionCache.
266 Args:
267 digest (Digest): The digest to get the bucket name for.
269 Returns:
270 str: The bucket name corresponding to the given Digest.
272 """
273 try:
274 return self._bucket_template.format(digest=digest.hash)
275 except IndexError:
276 LOGGER.error(
277 (
278 "Could not generate bucket name for digest. "
279 "This is either a misconfiguration in the BuildGrid S3 "
280 "ActionCache bucket configuration, or a badly formed request."
281 ),
282 tags=dict(digest=digest),
283 )
284 raise
286 def _get_s3object(self, digest: Digest) -> s3utils.S3Object:
287 return s3utils.S3Object(self._get_bucket_name(digest), self._get_key(digest))