Allow local deployments of public models without requiring AWS creds

pkg/workloads/cortex/lib/api/predictor.py

@@ -523,7 +523,7 @@ def model_downloader(
         f"downloading from bucket {bucket_name}/{model_path}, model {model_name} of version {model_version}, temporarily to {temp_dir} and then finally to {model_dir}"
     )
 
-    s3_client = S3(bucket_name, client_config={})
+    s3_client = S3(bucket_name)
 
     # validate upstream S3 model
     sub_paths, ts = s3_client.search(model_path)

pkg/workloads/cortex/lib/model/cron.py

@@ -144,7 +144,7 @@ def find_all_s3_models(
     # validate models stored in S3 that were specified with predictor:models:dir field
     if is_dir_used:
         bucket_name, models_path = S3.deconstruct_s3_path(models_dir)
-        s3_client = S3(bucket_name, client_config={})
+        s3_client = S3(bucket_name)
         sub_paths, timestamps = s3_client.search(models_path)
         model_paths, ooa_ids = validate_models_dir_paths(sub_paths, predictor_type, models_path)
         model_names = [os.path.basename(model_path) for model_path in model_paths]
@@ -171,7 +171,7 @@ def find_all_s3_models(
         for idx, path in enumerate(s3_paths):
             if S3.is_valid_s3_path(path):
                 bucket_name, model_path = S3.deconstruct_s3_path(path)
-                s3_client = S3(bucket_name, client_config={})
+                s3_client = S3(bucket_name)
                 sb, model_path_ts = s3_client.search(model_path)
                 try:
                     ooa_ids.append(validate_model_paths(sb, predictor_type, model_path))
@@ -451,7 +451,7 @@ def _refresh_model(
         sub_paths: List[str],
         bucket_name: str,
     ) -> None:
-        s3_client = S3(bucket_name, client_config={})
+        s3_client = S3(bucket_name)
 
         ondisk_model_path = os.path.join(self._download_dir, model_name)
         for version, model_ts in zip(versions, timestamps):
@@ -1059,7 +1059,7 @@ def _refresh_model(
         sub_paths: List[str],
         bucket_name: str,
     ) -> None:
-        s3_client = S3(bucket_name, client_config={})
+        s3_client = S3(bucket_name)
 
         ondisk_model_path = os.path.join(self._download_dir, model_name)
         for version, model_ts in zip(versions, timestamps):

pkg/workloads/cortex/lib/storage/s3.py

@@ -37,6 +37,9 @@ def __init__(self, bucket=None, region=None, client_config={}):
         if region is not None:
             client_config["region_name"] = region
 
+        if not (os.getenv("AWS_ACCESS_KEY_ID") and os.getenv("AWS_SECRET_ACCESS_KEY")):
+            client_config["config"] = botocore.client.Config(signature_version=botocore.UNSIGNED)
+
         self.s3 = boto3.client("s3", **client_config)
 
     @staticmethod