##### General

- Overview
- Single Node Setup
- Cluster Setup
- Commands Reference
- FileSystem Shell
- Compatibility Specification
- Downstream Developer's Guide
- Admin Compatibility Guide
- Interface Classification
- FileSystem Specification

##### Common

- CLI Mini Cluster
- Native Libraries
- Proxy User
- Rack Awareness
- Secure Mode
- Service Level Authorization
- HTTP Authentication
- Credential Provider API
- Hadoop KMS
- Tracing
- Unix Shell Guide

##### HDFS

- Architecture
- User Guide
- Commands Reference
- NameNode HA With QJM
- NameNode HA With NFS
- Observer NameNode
- Federation
- ViewFs
- ViewFsOverloadScheme
- Snapshots
- Edits Viewer
- Image Viewer
- Permissions and HDFS
- Quotas and HDFS
- libhdfs (C API)
- WebHDFS (REST API)
- HttpFS
- Short Circuit Local Reads
- Centralized Cache Management
- NFS Gateway
- Rolling Upgrade
- Extended Attributes
- Transparent Encryption
- Multihoming
- Storage Policies
- Memory Storage Support
- Synthetic Load Generator
- Erasure Coding
- Disk Balancer
- Upgrade Domain
- DataNode Admin
- Router Federation
- Provided Storage

##### MapReduce

- Tutorial
- Commands Reference
- Compatibility with 1.x
- Encrypted Shuffle
- Pluggable Shuffle/Sort
- Distributed Cache Deploy
- Support for YARN Shared Cache

##### MapReduce REST APIs

- MR Application Master
- MR History Server

##### YARN

- Architecture
- Commands Reference
- Capacity Scheduler
- Fair Scheduler
- ResourceManager Restart
- ResourceManager HA
- Resource Model
- Node Labels
- Node Attributes
- Web Application Proxy
- Timeline Server
- Timeline Service V.2
- Writing YARN Applications
- YARN Application Security
- NodeManager
- Running Applications in Docker Containers
- Using CGroups
- Secure Containers
- Registry
- Reservation System
- Graceful Decommission
- Opportunistic Containers
- YARN Federation
- Shared Cache
- Using GPU
- Using FPGA
- Placement Constraints
- YARN UI2

##### YARN REST APIs

- Introduction
- Resource Manager
- Node Manager
- Timeline Server
- Timeline Service V.2

##### YARN Service

- Overview
- QuickStart
- Concepts
- Yarn Service API
- Service Discovery
- System Services

##### Submarine

- Index
- QuickStart
- Examples

##### Hadoop Compatible File Systems

- Aliyun OSS
- Amazon S3
- Azure Blob Storage
- Azure Data Lake Storage
- OpenStack Swift

##### Auth

- Overview
- Examples
- Configuration
- Building

##### Tools

- Hadoop Streaming
- Hadoop Archives
- Hadoop Archive Logs
- DistCp
- GridMix
- Rumen
- Resource Estimator Service
- Scheduler Load Simulator
- Hadoop Benchmarking

##### Reference

- Changelog and Release Notes
- Java API docs
- Unix Shell API
- Metrics

##### Configuration

- core-default.xml
- hdfs-default.xml
- hdfs-rbf-default.xml
- mapred-default.xml
- yarn-default.xml
- kms-default.xml
- httpfs-default.xml
- Deprecated Properties

# Hadoop HDFS over HTTP - Documentation Sets

HttpFS is a server that provides a REST HTTP gateway supporting all HDFS File System operations (read and write). And it is interoperable with the webhdfs REST HTTP API.

HttpFS can be used to transfer data between clusters running different versions of Hadoop (overcoming RPC versioning issues), for example using Hadoop DistCP.

HttpFS can be used to access data in HDFS on a cluster behind of a firewall (the HttpFS server acts as a gateway and is the only system that is allowed to cross the firewall into the cluster).

HttpFS can be used to access data in HDFS using HTTP utilities (such as curl and wget) and HTTP libraries Perl from other languages than Java.

The webhdfs client FileSystem implementation can be used to access HttpFS using the Hadoop filesystem command (`hadoop fs`) line tool as well as from Java applications using the Hadoop FileSystem Java API.

HttpFS has built-in security supporting Hadoop pseudo authentication and HTTP SPNEGO Kerberos and other pluggable authentication mechanisms. It also provides Hadoop proxy user support.

## How Does HttpFS Works?

HttpFS is a separate service from Hadoop NameNode.

HttpFS itself is Java Jetty web-application.

HttpFS HTTP web-service API calls are HTTP REST calls that map to a HDFS file system operation. For example, using the `curl` Unix command:

- `$ curl 'http://httpfs-host:14000/webhdfs/v1/user/foo/README.txt?op=OPEN&user.name=foo'` returns the contents of the HDFS `/user/foo/README.txt` file.

- `$ curl 'http://httpfs-host:14000/webhdfs/v1/user/foo?op=LISTSTATUS&user.name=foo'` returns the contents of the HDFS `/user/foo` directory in JSON format.

- `$ curl 'http://httpfs-host:14000/webhdfs/v1/user/foo?op=GETTRASHROOT&user.name=foo'` returns the path `/user/foo/.Trash`, if `/` is an encrypted zone, returns the path `/.Trash/foo`. See more details about trash path in an encrypted zone.

- `$ curl -X POST 'http://httpfs-host:14000/webhdfs/v1/user/foo/bar?op=MKDIRS&user.name=foo'` creates the HDFS `/user/foo/bar` directory.

## User and Developer Documentation

- HttpFS Server Setup

- Using HTTP Tools