jorisvandenbossche commented on a change in pull request #8065:
URL: https://github.com/apache/arrow/pull/8065#discussion_r480953625
##########
File path: docs/source/python/filesystems.rst
##########
@@ -69,3 +135,66 @@ here is how you can read contents from a S3 bucket::
>>> f = s3.open_input_stream('my-test-bucket/Dir1/File2')
>>> f.readall()
b'some data'
+
+
+Hadoop File System (HDFS)
+-------------------------
+
+PyArrow comes with bindings to the Hadoop File System (based on C++ bindings
+using ``libhdfs``, a JNI-based interface to the Java Hadoop client). You
connect
+using the `class`:HadoopFileSystem: constructor::
+
+.. code-block:: python
+
+ from pyarrow import fs
+ hdfs = fs.HadoopFileSystem(host, port, user=user,
kerb_ticket=ticket_cache_path)
+
+The ``libhdfs`` library is loaded **at runtime**
+(rather than at link / library load time, since the library may not be in your
+LD_LIBRARY_PATH), and relies on some environment variables.
+
+* ``HADOOP_HOME``: the root of your installed Hadoop distribution. Often has
+ `lib/native/libhdfs.so`.
+
+* ``JAVA_HOME``: the location of your Java SDK installation.
+
+* ``ARROW_LIBHDFS_DIR`` (optional): explicit location of ``libhdfs.so`` if it
is
+ installed somewhere other than ``$HADOOP_HOME/lib/native``.
+
+* ``CLASSPATH``: must contain the Hadoop jars. You can set these using:
+
+ .. code-block:: shell
+
+ export CLASSPATH=`$HADOOP_HOME/bin/hdfs classpath --glob`
+
+ If ``CLASSPATH`` is not set, then it will be set automatically if the
+ ``hadoop`` executable is in your system path, or if ``HADOOP_HOME`` is set.
+
+
+Using fsspec-compatible filesystems
+-----------------------------------
+
+The filesystems mentioned above are natively supported by Arrow C++ / PyArrow.
+The Python ecosystem, however, also has several filesystem packages. Those
+packages following the
+`fsspec <https://filesystem-spec.readthedocs.io/en/latest/>`__ interface can be
Review comment:
The double underscore also works, and is called "anonymous hyperlink".
IIRC, the above syntax is fine for one-off inline links (if you would use the
same "fsspec" text somewhere else in a hyperlink in the docs, then sphinx would
warn about a duplicate target name if using a single underscore)
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