upload: Lazily import boto3.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

zerver/lib/export.py

@@ -16,7 +16,7 @@ from collections.abc import Callable, Iterable, Mapping
 from contextlib import suppress
 from datetime import datetime
 from functools import cache
-from typing import Any, Optional, TypeAlias, TypedDict
+from typing import TYPE_CHECKING, Any, Optional, TypeAlias, TypedDict
 
 import orjson
 from django.apps import apps
@@ -24,7 +24,6 @@ from django.conf import settings
 from django.db.models import Exists, OuterRef, Q
 from django.forms.models import model_to_dict
 from django.utils.timezone import is_naive as timezone_is_naive
-from mypy_boto3_s3.service_resource import Object
 
 import zerver.lib.upload
 from analytics.models import RealmCount, StreamCount, UserCount
@@ -77,6 +76,9 @@ from zerver.models.realm_audit_logs import AuditLogEventType
 from zerver.models.realms import EXPORT_FULL_WITH_CONSENT, EXPORT_PUBLIC, get_realm
 from zerver.models.users import get_system_bot, get_user_profile_by_id
 
+if TYPE_CHECKING:
+    from mypy_boto3_s3.service_resource import Object
+
 # Custom mypy types follow:
 Record: TypeAlias = dict[str, Any]
 TableName = str
@@ -1624,7 +1626,7 @@ def export_uploads_and_avatars(
 
 
 def _get_exported_s3_record(
-    bucket_name: str, key: Object, processing_emoji: bool
+    bucket_name: str, key: "Object", processing_emoji: bool
 ) -> dict[str, Any]:
     # Helper function for export_files_from_s3
     record: dict[str, Any] = dict(
@@ -1673,7 +1675,7 @@ def _get_exported_s3_record(
 
 
 def _save_s3_object_to_file(
-    key: Object,
+    key: "Object",
     output_dir: str,
     processing_uploads: bool,
 ) -> None:

zerver/lib/upload/s3.py

@@ -3,18 +3,15 @@ import os
 import secrets
 from collections.abc import Callable, Iterator
 from datetime import datetime
-from typing import IO, Any, BinaryIO, Literal
+from typing import IO, TYPE_CHECKING, Any, BinaryIO, Literal
 from urllib.parse import urljoin, urlsplit, urlunsplit
 
-import boto3
 import botocore
 import pyvips
 from botocore.client import Config
 from botocore.response import StreamingBody
 from django.conf import settings
 from django.utils.http import content_disposition_header
-from mypy_boto3_s3.client import S3Client
-from mypy_boto3_s3.service_resource import Bucket, Object
 from typing_extensions import override
 
 from zerver.lib.partial import partial
@@ -22,6 +19,10 @@ from zerver.lib.thumbnail import resize_avatar, resize_logo
 from zerver.lib.upload.base import INLINE_MIME_TYPES, StreamingSourceWithSize, ZulipUploadBackend
 from zerver.models import Realm, RealmEmoji, UserProfile
 
+if TYPE_CHECKING:
+    from mypy_boto3_s3.client import S3Client
+    from mypy_boto3_s3.service_resource import Bucket, Object
+
 # Duration that the signed upload URLs that we redirect to when
 # accessing uploaded files are available for clients to fetch before
 # they expire.
@@ -51,7 +52,9 @@ if settings.S3_SKIP_PROXY is True:  # nocoverage
     botocore.utils.should_bypass_proxies = lambda url: True
 
 
-def get_bucket(bucket_name: str, authed: bool = True) -> Bucket:
+def get_bucket(bucket_name: str, authed: bool = True) -> "Bucket":
+    import boto3
+
     return boto3.resource(
         "s3",
         aws_access_key_id=settings.S3_KEY if authed else None,
@@ -66,7 +69,7 @@ def get_bucket(bucket_name: str, authed: bool = True) -> Bucket:
 
 
 def upload_content_to_s3(
-    bucket: Bucket,
+    bucket: "Bucket",
     path: str,
     content_type: str | None,
     user_profile: UserProfile | None,
@@ -112,10 +115,10 @@ def upload_content_to_s3(
     )
 
 
-BOTO_CLIENT: S3Client | None = None
+BOTO_CLIENT: "S3Client | None" = None
 
 
-def get_boto_client() -> S3Client:
+def get_boto_client() -> "S3Client":
     """
     Creating the client takes a long time so we need to cache it.
     """
@@ -143,6 +146,8 @@ def get_signed_upload_url(path: str, force_download: bool = False) -> str:
 
 class S3UploadBackend(ZulipUploadBackend):
     def __init__(self) -> None:
+        from mypy_boto3_s3.service_resource import Bucket
+
         self.avatar_bucket = get_bucket(settings.S3_AVATAR_BUCKET)
         self.uploads_bucket = get_bucket(settings.S3_AUTH_UPLOADS_BUCKET)
         self.export_bucket: Bucket | None = None
@@ -151,7 +156,7 @@ class S3UploadBackend(ZulipUploadBackend):
 
         self.public_upload_url_base = self.construct_public_upload_url_base()
 
-    def delete_file_from_s3(self, path_id: str, bucket: Bucket) -> bool:
+    def delete_file_from_s3(self, path_id: str, bucket: "Bucket") -> bool:
         key = bucket.Object(path_id)
 
         try:
@@ -461,7 +466,7 @@ class S3UploadBackend(ZulipUploadBackend):
             # Strip off the signing query parameters, since this URL is public
             return urlsplit(signed_url)._replace(query="").geturl()
 
-    def export_object(self, tarball_path: str) -> Object:
+    def export_object(self, tarball_path: str) -> "Object":
         if self.export_bucket:
             return self.export_bucket.Object(
                 os.path.join(secrets.token_hex(16), os.path.basename(tarball_path))