REGR: Fixed reading from public S3 buckets with credentials

Closes pandas-dev#34626

This works in 1.0.4 I think, so no whatsnew.

Author: TomAugspurger

pandas/io/s3.py

@@ -16,8 +16,8 @@ def _strip_schema(url):
     return result.netloc + result.path
 
 
-def get_fs():
-    return s3fs.S3FileSystem(anon=False)
+def get_fs(anon=False):
+    return s3fs.S3FileSystem(anon=anon)
 
 
 def get_file_and_filesystem(
@@ -31,14 +31,14 @@ def get_file_and_filesystem(
     fs = get_fs()
     try:
         file = fs.open(_strip_schema(filepath_or_buffer), mode)
-    except (FileNotFoundError, NoCredentialsError):
+    except (FileNotFoundError, NoCredentialsError, PermissionError):
         # boto3 has troubles when trying to access a public file
         # when credentialed...
         # An OSError is raised if you have credentials, but they
         # aren't valid for that bucket.
         # A NoCredentialsError is raised if you don't have creds
         # for that bucket.
-        fs = get_fs()
+        fs = get_fs(anon=True)
         file = fs.open(_strip_schema(filepath_or_buffer), mode)
     return file, fs
 

pandas/tests/io/test_s3.py

@@ -1,8 +1,10 @@
 from io import BytesIO
+import os
 
 import pytest
 
 from pandas import read_csv
+import pandas._testing as tm
 
 from pandas.io.common import is_s3_url
 
@@ -23,3 +25,23 @@ def test_streaming_s3_objects():
     for el in data:
         body = StreamingBody(BytesIO(el), content_length=len(el))
         read_csv(body)
+
+
+@tm.network
+@pytest.mark.slow
+def test_read_s3_public():
+    # ensure we can read from a public bucket with credentials
+    pytest.importorskip("s3fs")
+
+    with tm.ensure_safe_environment_variables():
+        # temporary workaround as moto fails for botocore >= 1.11 otherwise,
+        # see https://github.com/spulec/moto/issues/1924 & 1952
+        os.environ.setdefault("AWS_ACCESS_KEY_ID", "foobar_key")
+        os.environ.setdefault("AWS_SECRET_ACCESS_KEY", "foobar_secret")
+        df = read_csv(
+            "s3://gdelt-open-data/events/20130420.export.csv",
+            nrows=5,
+            sep="\t",
+            header=None,
+        )
+        assert len(df) == 5