WebHDFS REST API

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Italics Important phrases and words.

Introduction

The HTTP REST API supports the complete FileSystem/FileContext interface for HDFS. The operations and the corresponding FileSystem/FileContext methods are shown in the next section. The Section HTTP Query Parameter Dictionary specifies the parameter details such as the defaults and the valid values.

Operations

FileSystem URIs vs HTTP URLs

The FileSystem scheme of WebHDFS is “webhdfs://”. A WebHDFS FileSystem URI has the following format.

  webhdfs://<HOST>:<HTTP_PORT>/<PATH>

The above WebHDFS URI corresponds to the below HDFS URI.

  hdfs://<HOST>:<RPC_PORT>/<PATH>

In the REST API, the prefix “/webhdfs/v1” is inserted in the path and a query is appended at the end. Therefore, the corresponding HTTP URL has the following format.

  http://<HOST>:<HTTP_PORT>/webhdfs/v1/<PATH>?op=...

Note that if WebHDFS is secured with SSL, then the scheme should be “swebhdfs://”.

  swebhdfs://<HOST>:<HTTP_PORT>/<PATH>

HDFS Configuration Options

Below are the HDFS configuration options for WebHDFS.

Property Name Description
dfs.webhdfs.enabled Enable/disable WebHDFS in Namenodes and Datanodes
dfs.web.authentication.kerberos.principal The HTTP Kerberos principal used by Hadoop-Auth in the HTTP endpoint. The HTTP Kerberos principal MUST start with ‘HTTP/’ per Kerberos HTTP SPNEGO specification. A value of “*” will use all HTTP principals found in the keytab.
dfs.web.authentication.kerberos.keytab The Kerberos keytab file with the credentials for the HTTP Kerberos principal used by Hadoop-Auth in the HTTP endpoint.
dfs.webhdfs.socket.connect-timeout How long to wait for a connection to be established before failing. Specified as a time duration, ie numerical value followed by a units symbol, eg 2m for two minutes. Defaults to 60s.
dfs.webhdfs.socket.read-timeout How long to wait for data to arrive before failing. Defaults to 60s.

Authentication

When security is off, the authenticated user is the username specified in the user.name query parameter. If the user.name parameter is not set, the server may either set the authenticated user to a default web user, if there is any, or return an error response.

When security is on, authentication is performed by either Hadoop delegation token or Kerberos SPNEGO. If a token is set in the delegation query parameter, the authenticated user is the user encoded in the token. If the delegation parameter is not set, the user is authenticated by Kerberos SPNEGO.

Below are examples using the curl command tool.

  1. Authentication when security is off:

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?[user.name=<USER>&]op=..."

  2. Authentication using Kerberos SPNEGO when security is on:

    curl -i --negotiate -u : "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=..."

  3. Authentication using Hadoop delegation token when security is on:

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?delegation=<TOKEN>&op=..."

See also: Authentication for Hadoop HTTP web-consoles

Additionally, WebHDFS supports OAuth2 on the client side. The Namenode and Datanodes do not currently support clients using OAuth2 but other backends that implement the WebHDFS REST interface may.

WebHDFS supports two type of OAuth2 code grants (user-provided refresh and access token or user provided credential) by default and provides a pluggable mechanism for implementing other OAuth2 authentications per the OAuth2 RFC, or custom authentications. When using either of the provided code grant mechanisms, the WebHDFS client will refresh the access token as necessary.

OAuth2 should only be enabled for clients not running with Kerberos SPENGO.

OAuth2 code grant mechanism Description Value of dfs.webhdfs.oauth2.access.token.provider that implements code grant
Authorization Code Grant The user provides an initial access token and refresh token, which are then used to authenticate WebHDFS requests and obtain replacement access tokens, respectively. org.apache.hadoop.hdfs.web.oauth2.ConfRefreshTokenBasedAccessTokenProvider
Client Credentials Grant The user provides a credential which is used to obtain access tokens, which are then used to authenticate WebHDFS requests. org.apache.hadoop.hdfs.web.oauth2.ConfCredentialBasedAccessTokenProvider

The following properties control OAuth2 authentication.

OAuth2 related property Description
dfs.webhdfs.oauth2.enabled Boolean to enable/disable OAuth2 authentication
dfs.webhdfs.oauth2.access.token.provider Class name of an implementation of org.apache.hadoop.hdfs.web.oauth.AccessTokenProvider. Two are provided with the code, as described above, or the user may specify a user-provided implementation. The default value for this configuration key is the ConfCredentialBasedAccessTokenProvider implementation.
dfs.webhdfs.oauth2.client.id Client id used to obtain access token with either credential or refresh token
dfs.webhdfs.oauth2.refresh.url URL against which to post for obtaining bearer token with either credential or refresh token
dfs.webhdfs.oauth2.access.token (required if using ConfRefreshTokenBasedAccessTokenProvider) Initial access token with which to authenticate
dfs.webhdfs.oauth2.refresh.token (required if using ConfRefreshTokenBasedAccessTokenProvider) Initial refresh token to use to obtain new access tokens
dfs.webhdfs.oauth2.refresh.token.expires.ms.since.epoch (required if using ConfRefreshTokenBasedAccessTokenProvider) Access token expiration measured in milliseconds since Jan 1, 1970. Note this is a different value than provided by OAuth providers and has been munged as described in interface to be suitable for a client application
dfs.webhdfs.oauth2.credential (required if using ConfCredentialBasedAccessTokenProvider). Credential used to obtain initial and subsequent access tokens.

Proxy Users

When the proxy user feature is enabled, a proxy user P may submit a request on behalf of another user U. The username of U must be specified in the doas query parameter unless a delegation token is presented in authentication. In such case, the information of both users P and U must be encoded in the delegation token.

  1. A proxy request when security is off:

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?[user.name=<USER>&]doas=<USER>&op=..."

  2. A proxy request using Kerberos SPNEGO when security is on:

    curl -i --negotiate -u : "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?doas=<USER>&op=..."

  3. A proxy request using Hadoop delegation token when security is on:

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?delegation=<TOKEN>&op=..."

Cross-Site Request Forgery Prevention

WebHDFS supports an optional, configurable mechanism for cross-site request forgery (CSRF) prevention. When enabled, WebHDFS HTTP requests to the NameNode or DataNode must include a custom HTTP header. Configuration properties allow adjusting which specific HTTP methods are protected and the name of the HTTP header. The value sent in the header is not relevant. Only the presence of a header by that name is required.

Enabling CSRF prevention also sets up the WebHdfsFileSystem class to send the required header. This ensures that CLI commands like hdfs dfs and hadoop distcp continue to work correctly when used with webhdfs: URIs.

Enabling CSRF prevention also sets up the NameNode web UI to send the required header. After enabling CSRF prevention and restarting the NameNode, existing users of the NameNode web UI need to refresh the browser to reload the page and find the new configuration.

The following properties control CSRF prevention.

Property Description Default Value
dfs.webhdfs.rest-csrf.enabled If true, then enables WebHDFS protection against cross-site request forgery (CSRF). The WebHDFS client also uses this property to determine whether or not it needs to send the custom CSRF prevention header in its HTTP requests. false
dfs.webhdfs.rest-csrf.custom-header The name of a custom header that HTTP requests must send when protection against cross-site request forgery (CSRF) is enabled for WebHDFS by setting dfs.webhdfs.rest-csrf.enabled to true. The WebHDFS client also uses this property to determine whether or not it needs to send the custom CSRF prevention header in its HTTP requests. X-XSRF-HEADER
dfs.webhdfs.rest-csrf.methods-to-ignore A comma-separated list of HTTP methods that do not require HTTP requests to include a custom header when protection against cross-site request forgery (CSRF) is enabled for WebHDFS by setting dfs.webhdfs.rest-csrf.enabled to true. The WebHDFS client also uses this property to determine whether or not it needs to send the custom CSRF prevention header in its HTTP requests. GET,OPTIONS,HEAD,TRACE
dfs.webhdfs.rest-csrf.browser-useragents-regex A comma-separated list of regular expressions used to match against an HTTP request’s User-Agent header when protection against cross-site request forgery (CSRF) is enabled for WebHDFS by setting dfs.webhdfs.reset-csrf.enabled to true. If the incoming User-Agent matches any of these regular expressions, then the request is considered to be sent by a browser, and therefore CSRF prevention is enforced. If the request’s User-Agent does not match any of these regular expressions, then the request is considered to be sent by something other than a browser, such as scripted automation. In this case, CSRF is not a potential attack vector, so the prevention is not enforced. This helps achieve backwards-compatibility with existing automation that has not been updated to send the CSRF prevention header. ^Mozilla.*,^Opera.*

The following is an example curl call that uses the -H option to include the custom header in the request.

    curl -i -L -X PUT -H 'X-XSRF-HEADER: ""' 'http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=CREATE'

WebHDFS Retry Policy

WebHDFS supports an optional, configurable retry policy for resilient copy of large files that could timeout, or copy file between HA clusters that could failover during the copy.

The following properties control WebHDFS retry and failover policy.

Property Description Default Value
dfs.http.client.retry.policy.enabled If “true”, enable the retry policy of WebHDFS client. If “false”, retry policy is turned off. false
dfs.http.client.retry.policy.spec Specify a policy of multiple linear random retry for WebHDFS client, e.g. given pairs of number of retries and sleep time (n0, t0), (n1, t1), …, the first n0 retries sleep t0 milliseconds on average, the following n1 retries sleep t1 milliseconds on average, and so on. 10000,6,60000,10
dfs.http.client.failover.max.attempts Specify the max number of failover attempts for WebHDFS client in case of network exception. 15
dfs.http.client.retry.max.attempts Specify the max number of retry attempts for WebHDFS client, if the difference between retried attempts and failovered attempts is larger than the max number of retry attempts, there will be no more retries. 10
dfs.http.client.failover.sleep.base.millis Specify the base amount of time in milliseconds upon which the exponentially increased sleep time between retries or failovers is calculated for WebHDFS client. 500
dfs.http.client.failover.sleep.max.millis Specify the upper bound of sleep time in milliseconds between retries or failovers for WebHDFS client. 15000

File and Directory Operations

Create and Write to a File

  • Step 1: Submit a HTTP PUT request without automatically following redirects and without sending the file data.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=CREATE
                    [&overwrite=<true |false>][&blocksize=<LONG>][&replication=<SHORT>]
                    [&permission=<OCTAL>][&buffersize=<INT>]"

    The request is redirected to a datanode where the file data is to be written:

    HTTP/1.1 307 TEMPORARY_REDIRECT
Location: http://<DATANODE>:<PORT>/webhdfs/v1/<PATH>?op=CREATE...
Content-Length: 0

  • Step 2: Submit another HTTP PUT request using the URL in the Location header with the file data to be written.

    curl -i -X PUT -T <LOCAL_FILE> "http://<DATANODE>:<PORT>/webhdfs/v1/<PATH>?op=CREATE..."

    The client receives a 201 Created response with zero content length and the WebHDFS URI of the file in the Location header:

    HTTP/1.1 201 Created
Location: webhdfs://<HOST>:<PORT>/<PATH>
Content-Length: 0

If no permissions are specified, the newly created file will be assigned with default 755 permission. This also applies for new directories. No umask mode will be applied from server side (so “fs.permissions.umask-mode” value configuration set on Namenode side will have no effect).

Note that the reason of having two-step create/append is for preventing clients to send out data before the redirect. This issue is addressed by the “Expect: 100-continue” header in HTTP/1.1; see RFC 2616, Section 8.2.3. Unfortunately, there are software library bugs (e.g. Jetty 6 HTTP server and Java 6 HTTP client), which do not correctly implement “Expect: 100-continue”. The two-step create/append is a temporary workaround for the software library bugs.

See also: overwrite, blocksize, replication, permission, buffersize, FileSystem.create

Append to a File

  • Step 1: Submit a HTTP POST request without automatically following redirects and without sending the file data.

    curl -i -X POST "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=APPEND[&buffersize=<INT>]"

    The request is redirected to a datanode where the file data is to be appended:

    HTTP/1.1 307 TEMPORARY_REDIRECT
Location: http://<DATANODE>:<PORT>/webhdfs/v1/<PATH>?op=APPEND...
Content-Length: 0

  • Step 2: Submit another HTTP POST request using the URL in the Location header with the file data to be appended.

    curl -i -X POST -T <LOCAL_FILE> "http://<DATANODE>:<PORT>/webhdfs/v1/<PATH>?op=APPEND..."

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See the note in the previous section for the description of why this operation requires two steps.

See also: buffersize, FileSystem.append

Concat File(s)

  • Submit a HTTP POST request.

    curl -i -X POST "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=CONCAT&sources=<PATHS>"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: sources, FileSystem.concat

Open and Read a File

  • Submit a HTTP GET request with automatically following redirects.

    curl -i -L "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=OPEN
                    [&offset=<LONG>][&length=<LONG>][&buffersize=<INT>]"

    The request is redirected to a datanode where the file data can be read:

    HTTP/1.1 307 TEMPORARY_REDIRECT
Location: http://<DATANODE>:<PORT>/webhdfs/v1/<PATH>?op=OPEN...
Content-Length: 0

    The client follows the redirect to the datanode and receives the file data:

    HTTP/1.1 200 OK
Content-Type: application/octet-stream
Content-Length: 22

Hello, webhdfs user!

See also: offset, length, buffersize, FileSystem.open

Make a Directory

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=MKDIRS[&permission=<OCTAL>]"

    The client receives a response with a boolean JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{"boolean": true}

If no permissions are specified, the newly created directory will be assigned with default 755 permission. This also applies to new files created. No umask mode will be applied from server side (so “fs.permissions.umask-mode” value configuration set on Namenode side will have no effect).

See also: permission, FileSystem.mkdirs

Create a Symbolic Link

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=CREATESYMLINK
                              &destination=<PATH>[&createParent=<true |false>]"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: destination, createParent, FileSystem.createSymlink

Rename a File/Directory

  • Submit a HTTP PUT request.

    curl -i -X PUT "<HOST>:<PORT>/webhdfs/v1/<PATH>?op=RENAME&destination=<PATH>"

    The client receives a response with a boolean JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{"boolean": true}

See also: destination, FileSystem.rename

Delete a File/Directory

  • Submit a HTTP DELETE request.

    curl -i -X DELETE "http://<host>:<port>/webhdfs/v1/<path>?op=DELETE
                              [&recursive=<true |false>]"

    The client receives a response with a boolean JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{"boolean": true}

See also: recursive, FileSystem.delete

Truncate a File

  • Submit a HTTP POST request.

    curl -i -X POST "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=TRUNCATE&newlength=<LONG>"

    The client receives a response with a boolean JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{"boolean": true}

See also: newlength, FileSystem.truncate

Status of a File/Directory

  • Submit a HTTP GET request.

    curl -i  "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=GETFILESTATUS"

    The client receives a response with a FileStatus JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{
  "FileStatus":
  {
    "accessTime"      : 0,
    "blockSize"       : 0,
    "group"           : "supergroup",
    "length"          : 0,             //in bytes, zero for directories
    "modificationTime": 1320173277227,
    "owner"           : "webuser",
    "pathSuffix"      : "",
    "permission"      : "777",
    "replication"     : 0,
    "type"            : "DIRECTORY"    //enum {FILE, DIRECTORY, SYMLINK}
  }
}

See also: FileSystem.getFileStatus

List a Directory

  • Submit a HTTP GET request.

    curl -i  "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=LISTSTATUS"

    The client receives a response with a FileStatuses JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Content-Length: 427

{
  "FileStatuses":
  {
    "FileStatus":
    [
      {
        "accessTime"      : 1320171722771,
        "blockSize"       : 33554432,
        "group"           : "supergroup",
        "length"          : 24930,
        "modificationTime": 1320171722771,
        "owner"           : "webuser",
        "pathSuffix"      : "a.patch",
        "permission"      : "644",
        "replication"     : 1,
        "type"            : "FILE"
      },
      {
        "accessTime"      : 0,
        "blockSize"       : 0,
        "group"           : "supergroup",
        "length"          : 0,
        "modificationTime": 1320895981256,
        "owner"           : "szetszwo",
        "pathSuffix"      : "bar",
        "permission"      : "711",
        "replication"     : 0,
        "type"            : "DIRECTORY"
      },
      ...
    ]
  }
}

See also: FileSystem.listStatus

Other File System Operations

Get Content Summary of a Directory

  • Submit a HTTP GET request.

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=GETCONTENTSUMMARY"

    The client receives a response with a ContentSummary JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{
  "ContentSummary":
  {
    "directoryCount": 2,
    "fileCount"     : 1,
    "length"        : 24930,
    "quota"         : -1,
    "spaceConsumed" : 24930,
    "spaceQuota"    : -1,
    "typeQuota":
    {
      "ARCHIVE":
      {
        "consumed": 500,
        "quota": 10000
      },
      "DISK":
      {
        "consumed": 500,
        "quota": 10000
      },
      "SSD":
      {
        "consumed": 500,
        "quota": 10000
      }
    }
  }
}

See also: FileSystem.getContentSummary

Get File Checksum

  • Submit a HTTP GET request.

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=GETFILECHECKSUM"

    The request is redirected to a datanode:

    HTTP/1.1 307 TEMPORARY_REDIRECT
Location: http://<DATANODE>:<PORT>/webhdfs/v1/<PATH>?op=GETFILECHECKSUM...
Content-Length: 0

    The client follows the redirect to the datanode and receives a FileChecksum JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{
  "FileChecksum":
  {
    "algorithm": "MD5-of-1MD5-of-512CRC32",
    "bytes"    : "eadb10de24aa315748930df6e185c0d ...",
    "length"   : 28
  }
}

See also: FileSystem.getFileChecksum

Get Home Directory

  • Submit a HTTP GET request.

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/?op=GETHOMEDIRECTORY"

    The client receives a response with a Path JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{"Path": "/user/szetszwo"}

See also: FileSystem.getHomeDirectory

Set Permission

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=SETPERMISSION
                              [&permission=<OCTAL>]"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: permission, FileSystem.setPermission

Set Owner

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=SETOWNER
                              [&owner=<USER>][&group=<GROUP>]"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: owner, group, FileSystem.setOwner

Set Replication Factor

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=SETREPLICATION
                              [&replication=<SHORT>]"

    The client receives a response with a boolean JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{"boolean": true}

See also: replication, FileSystem.setReplication

Set Access or Modification Time

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=SETTIMES
                              [&modificationtime=<TIME>][&accesstime=<TIME>]"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: modificationtime, accesstime, FileSystem.setTimes

Modify ACL Entries

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=MODIFYACLENTRIES
                              &aclspec=<ACLSPEC>"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: FileSystem.modifyAclEntries

Remove ACL Entries

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=REMOVEACLENTRIES
                              &aclspec=<ACLSPEC>"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: FileSystem.removeAclEntries

Remove Default ACL

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=REMOVEDEFAULTACL"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: FileSystem.removeDefaultAcl

Remove ACL

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=REMOVEACL"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: FileSystem.removeAcl

Set ACL

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=SETACL
                              &aclspec=<ACLSPEC>"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: FileSystem.setAcl

Get ACL Status

  • Submit a HTTP GET request.

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=GETACLSTATUS"

    The client receives a response with a AclStatus JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{
    "AclStatus": {
        "entries": [
            "user:carla:rw-", 
            "group::r-x"
        ], 
        "group": "supergroup", 
        "owner": "hadoop", 
        "permission":"775",
        "stickyBit": false
    }
}

See also: FileSystem.getAclStatus

Check access

  • Submit a HTTP GET request.

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=CHECKACCESS
                              &fsaction=<FSACTION>

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: FileSystem.access

Storage Policy Operations

Get all Storage Policies

  • Submit a HTTP GET request.

    curl -i "http://<HOST>:<PORT>/webhdfs/v1?op=GETALLSTORAGEPOLICY"

    The client receives a response with a BlockStoragePolicies JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{
    "BlockStoragePolicies": {
        "BlockStoragePolicy": [
           {
               "copyOnCreateFile": false,
               "creationFallbacks": [],
               "id": 2,
               "name": "COLD",
               "replicationFallbacks": [],
               "storageTypes": ["ARCHIVE"]
           },
           {
               "copyOnCreateFile": false,
               "creationFallbacks": ["DISK","ARCHIVE"],
               "id": 5,
               "name": "WARM",
               "replicationFallbacks": ["DISK","ARCHIVE"],
               "storageTypes": ["DISK","ARCHIVE"]
           },
           {
               "copyOnCreateFile": false,
               "creationFallbacks": [],
               "id": 7,
               "name": "HOT",
               "replicationFallbacks": ["ARCHIVE"],
               "storageTypes": ["DISK"]
           },
           {
               "copyOnCreateFile": false,
               "creationFallbacks": ["SSD","DISK"],
               "id": 10,"name": "ONE_SSD",
               "replicationFallbacks": ["SSD","DISK"],
               "storageTypes": ["SSD","DISK"]
           },
           {
               "copyOnCreateFile": false,
               "creationFallbacks": ["DISK"],
               "id": 12,
               "name": "ALL_SSD",
               "replicationFallbacks": ["DISK"],
               "storageTypes": ["SSD"]
           },
           {
               "copyOnCreateFile": true,
               "creationFallbacks": ["DISK"],
               "id": 15,
               "name": "LAZY_PERSIST",
               "replicationFallbacks": ["DISK"],
               "storageTypes": ["RAM_DISK","DISK"]
           }
       ]
  • } }

See also: FileSystem.getAllStoragePolicies

Set Storage Policy

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=SETSTORAGEPOLICY
                              &storagepolicy=<policy>"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: FileSystem.setStoragePolicy

Unset Storage Policy

  • Submit a HTTP POT request.

    curl -i -X POST "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=UNSETSTORAGEPOLICY"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: FileSystem.unsetStoragePolicy

Get Storage Policy

  • Submit a HTTP GET request.

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=GETSTORAGEPOLICY"

    The client receives a response with a BlockStoragePolicy JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{
    "BlockStoragePolicy": {
        "copyOnCreateFile": false,
       "creationFallbacks": [],
        "id":7,
        "name":"HOT",
        "replicationFallbacks":["ARCHIVE"],
        "storageTypes":["DISK"]
    }
}

See also: FileSystem.getStoragePolicy

Extended Attributes(XAttrs) Operations

Set XAttr

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=SETXATTR
                              &xattr.name=<XATTRNAME>&xattr.value=<XATTRVALUE>
                              &flag=<FLAG>"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: FileSystem.setXAttr

Remove XAttr

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=REMOVEXATTR
                              &xattr.name=<XATTRNAME>"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: FileSystem.removeXAttr

Get an XAttr

  • Submit a HTTP GET request.

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=GETXATTRS
                              &xattr.name=<XATTRNAME>&encoding=<ENCODING>"

    The client receives a response with a XAttrs JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{
    "XAttrs": [
        {
            "name":"XATTRNAME",
            "value":"XATTRVALUE"
        }
    ]
}

See also: FileSystem.getXAttr

Get multiple XAttrs

  • Submit a HTTP GET request.

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=GETXATTRS
                              &xattr.name=<XATTRNAME1>&xattr.name=<XATTRNAME2>
                              &encoding=<ENCODING>"

    The client receives a response with a XAttrs JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{
    "XAttrs": [
        {
            "name":"XATTRNAME1",
            "value":"XATTRVALUE1"
        },
        {
            "name":"XATTRNAME2",
            "value":"XATTRVALUE2"
        }
    ]
}

See also: FileSystem.getXAttrs

Get all XAttrs

  • Submit a HTTP GET request.

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=GETXATTRS
                              &encoding=<ENCODING>"

    The client receives a response with a XAttrs JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{
    "XAttrs": [
        {
            "name":"XATTRNAME1",
            "value":"XATTRVALUE1"
        },
        {
            "name":"XATTRNAME2",
            "value":"XATTRVALUE2"
        },
        {
            "name":"XATTRNAME3",
            "value":"XATTRVALUE3"
        }
    ]
}

See also: FileSystem.getXAttrs

List all XAttrs

  • Submit a HTTP GET request.

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=LISTXATTRS"

    The client receives a response with a XAttrNames JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{
    "XAttrNames":"[\"XATTRNAME1\",\"XATTRNAME2\",\"XATTRNAME3\"]"
}

See also: FileSystem.listXAttrs

Snapshot Operations

Create Snapshot

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=CREATESNAPSHOT[&snapshotname=<SNAPSHOTNAME>]"

    The client receives a response with a Path JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{"Path": "/user/szetszwo/.snapshot/s1"}

See also: FileSystem.createSnapshot

Delete Snapshot

  • Submit a HTTP DELETE request.

    curl -i -X DELETE "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=DELETESNAPSHOT&snapshotname=<SNAPSHOTNAME>"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: FileSystem.deleteSnapshot

Rename Snapshot

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/<PATH>?op=RENAMESNAPSHOT
                   &oldsnapshotname=<SNAPSHOTNAME>&snapshotname=<SNAPSHOTNAME>"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: FileSystem.renameSnapshot

Delegation Token Operations

Get Delegation Token

  • Submit a HTTP GET request.

    curl -i "http://<HOST>:<PORT>/webhdfs/v1/?op=GETDELEGATIONTOKEN&renewer=<USER>&service=<SERVICE>&kind=<KIND>"

    The client receives a response with a Token JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{
  "Token":
  {
    "urlString": "JQAIaG9y..."
  }
}

See also: renewer, FileSystem.getDelegationToken, kind, service

Renew Delegation Token

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/?op=RENEWDELEGATIONTOKEN&token=<TOKEN>"

    The client receives a response with a long JSON object:

    HTTP/1.1 200 OK
Content-Type: application/json
Transfer-Encoding: chunked

{"long": 1320962673997}           //the new expiration time

See also: token, DelegationTokenAuthenticator.renewDelegationToken

Cancel Delegation Token

  • Submit a HTTP PUT request.

    curl -i -X PUT "http://<HOST>:<PORT>/webhdfs/v1/?op=CANCELDELEGATIONTOKEN&token=<TOKEN>"

    The client receives a response with zero content length:

    HTTP/1.1 200 OK
Content-Length: 0

See also: token, DelegationTokenAuthenticator.cancelDelegationToken

Error Responses

When an operation fails, the server may throw an exception. The JSON schema of error responses is defined in RemoteException JSON Schema. The table below shows the mapping from exceptions to HTTP response codes.

HTTP Response Codes

Exceptions HTTP Response Codes
IllegalArgumentException 400 Bad Request
UnsupportedOperationException 400 Bad Request
SecurityException 401 Unauthorized
IOException 403 Forbidden
FileNotFoundException 404 Not Found
RuntimeException 500 Internal Server Error

Below are examples of exception responses.

Illegal Argument Exception

HTTP/1.1 400 Bad Request
Content-Type: application/json
Transfer-Encoding: chunked

{
  "RemoteException":
  {
    "exception"    : "IllegalArgumentException",
    "javaClassName": "java.lang.IllegalArgumentException",
    "message"      : "Invalid value for webhdfs parameter \"permission\": ..."
  }
}

Security Exception

HTTP/1.1 401 Unauthorized
Content-Type: application/json
Transfer-Encoding: chunked

{
  "RemoteException":
  {
    "exception"    : "SecurityException",
    "javaClassName": "java.lang.SecurityException",
    "message"      : "Failed to obtain user group information: ..."
  }
}

Access Control Exception

HTTP/1.1 403 Forbidden
Content-Type: application/json
Transfer-Encoding: chunked

{
  "RemoteException":
  {
    "exception"    : "AccessControlException",
    "javaClassName": "org.apache.hadoop.security.AccessControlException",
    "message"      : "Permission denied: ..."
  }
}

File Not Found Exception

HTTP/1.1 404 Not Found
Content-Type: application/json
Transfer-Encoding: chunked

{
  "RemoteException":
  {
    "exception"    : "FileNotFoundException",
    "javaClassName": "java.io.FileNotFoundException",
    "message"      : "File does not exist: /foo/a.patch"
  }
}

JSON Schemas

All operations, except for OPEN, either return a zero-length response or a JSON response. For OPEN, the response is an octet-stream. The JSON schemas are shown below. See draft-zyp-json-schema-03 for the syntax definitions of the JSON schemas.

Note that the default value of additionalProperties is an empty schema which allows any value for additional properties. Therefore, all WebHDFS JSON responses allow any additional property. However, if additional properties are included in the responses, they are considered as optional properties in order to maintain compatibility.

ACL Status JSON Schema

{
  "name"      : "AclStatus",
  "properties":
  {
    "AclStatus":
    {
      "type"      : "object",
      "properties":
      {
        "entries":
        {
          "type": "array",
          "items":
          {
            "description": "ACL entry.",
            "type": "string"
          }
        },
        "group":
        {
          "description": "The group owner.",
          "type"       : "string",
          "required"   : true
        },
        "owner":
        {
          "description": "The user who is the owner.",
          "type"       : "string",
          "required"   : true
        },
        "stickyBit":
        {
          "description": "True if the sticky bit is on.",
          "type"       : "boolean",
          "required"   : true
        }
      }
    }
  }
}

XAttrs JSON Schema

{
  "name"      : "XAttrs",
  "properties":
  {
    "XAttrs":
    {
      "type"      : "array",
      "items":
      {
        "type"    : "object",
        "properties":
        {
          "name":
          {
            "description": "XAttr name.",
            "type"       : "string",
            "required"   : true
          },
          "value":
          {
            "description": "XAttr value.",
            "type"       : "string"
          }
        }
      }
    }
  }
}

XAttrNames JSON Schema

{
  "name"      : "XAttrNames",
  "properties":
  {
    "XAttrNames":
    {
      "description": "XAttr names.",
      "type"       : "string",
      "required"   : true
    }
  }
}

Boolean JSON Schema

{
  "name"      : "boolean",
  "properties":
  {
    "boolean":
    {
      "description": "A boolean value",
      "type"       : "boolean",
      "required"   : true
    }
  }
}

See also: MKDIRS, RENAME, DELETE, SETREPLICATION

ContentSummary JSON Schema

{
  "name"      : "ContentSummary",
  "properties":
  {
    "ContentSummary":
    {
      "type"      : "object",
      "properties":
      {
        "directoryCount":
        {
          "description": "The number of directories.",
          "type"       : "integer",
          "required"   : true
        },
        "fileCount":
        {
          "description": "The number of files.",
          "type"       : "integer",
          "required"   : true
        },
        "length":
        {
          "description": "The number of bytes used by the content.",
          "type"       : "integer",
          "required"   : true
        },
        "quota":
        {
          "description": "The namespace quota of this directory.",
          "type"       : "integer",
          "required"   : true
        },
        "spaceConsumed":
        {
          "description": "The disk space consumed by the content.",
          "type"       : "integer",
          "required"   : true
        },
        "spaceQuota":
        {
          "description": "The disk space quota.",
          "type"       : "integer",
          "required"   : true
        },
        "typeQuota":
        {
          "type"      : "object",
          "properties":
          {
            "ARCHIVE":
            {
              "type"      : "object",
              "properties":
              {
                "consumed":
                {
                  "description": "The storage type space consumed.",
                  "type"       : "integer",
                  "required"   : true
                },
                "quota":
                {
                  "description": "The storage type quota.",
                  "type"       : "integer",
                  "required"   : true
                }
              }
            },
            "DISK":
            {
              "type"      : "object",
              "properties":
              {
                "consumed":
                {
                  "description": "The storage type space consumed.",
                  "type"       : "integer",
                  "required"   : true
                },
                "quota":
                {
                  "description": "The storage type quota.",
                  "type"       : "integer",
                  "required"   : true
                }
              }
            },
            "SSD":
            {
              "type"      : "object",
              "properties":
              {
                "consumed":
                {
                  "description": "The storage type space consumed.",
                  "type"       : "integer",
                  "required"   : true
                },
                "quota":
                {
                  "description": "The storage type quota.",
                  "type"       : "integer",
                  "required"   : true
                }
              }
            }
          }
        }
      }
    }
  }
}

See also: GETCONTENTSUMMARY

FileChecksum JSON Schema

{
  "name"      : "FileChecksum",
  "properties":
  {
    "FileChecksum":
    {
      "type"      : "object",
      "properties":
      {
        "algorithm":
        {
          "description": "The name of the checksum algorithm.",
          "type"       : "string",
          "required"   : true
        },
        "bytes":
        {
          "description": "The byte sequence of the checksum in hexadecimal.",
          "type"       : "string",
          "required"   : true
        },
        "length":
        {
          "description": "The length of the bytes (not the length of the string).",
          "type"       : "integer",
          "required"   : true
        }
      }
    }
  }
}

FileStatus JSON Schema

{
  "name"      : "FileStatus",
  "properties":
  {
    "FileStatus": fileStatusProperties      //See FileStatus Properties
  }
}

See also: FileStatus Properties, GETFILESTATUS, FileStatus

FileStatus Properties

JavaScript syntax is used to define fileStatusProperties so that it can be referred in both FileStatus and FileStatuses JSON schemas.

var fileStatusProperties =
{
  "type"      : "object",
  "properties":
  {
    "accessTime":
    {
      "description": "The access time.",
      "type"       : "integer",
      "required"   : true
    },
    "blockSize":
    {
      "description": "The block size of a file.",
      "type"       : "integer",
      "required"   : true
    },
    "group":
    {
      "description": "The group owner.",
      "type"       : "string",
      "required"   : true
    },
    "length":
    {
      "description": "The number of bytes in a file.",
      "type"       : "integer",
      "required"   : true
    },
    "modificationTime":
    {
      "description": "The modification time.",
      "type"       : "integer",
      "required"   : true
    },
    "owner":
    {
      "description": "The user who is the owner.",
      "type"       : "string",
      "required"   : true
    },
    "pathSuffix":
    {
      "description": "The path suffix.",
      "type"       : "string",
      "required"   : true
    },
    "permission":
    {
      "description": "The permission represented as a octal string.",
      "type"       : "string",
      "required"   : true
    },
    "replication":
    {
      "description": "The number of replication of a file.",
      "type"       : "integer",
      "required"   : true
    },
   "symlink":                                         //an optional property
    {
      "description": "The link target of a symlink.",
      "type"       : "string"
    },
   "type":
    {
      "description": "The type of the path object.",
      "enum"       : ["FILE", "DIRECTORY", "SYMLINK"],
      "required"   : true
    }
  }
};

FileStatuses JSON Schema

A FileStatuses JSON object represents an array of FileStatus JSON objects.

{
  "name"      : "FileStatuses",
  "properties":
  {
    "FileStatuses":
    {
      "type"      : "object",
      "properties":
      {
        "FileStatus":
        {
          "description": "An array of FileStatus",
          "type"       : "array",
          "items"      : fileStatusProperties      //See FileStatus Properties
        }
      }
    }
  }
}

See also: FileStatus Properties, LISTSTATUS, FileStatus

Long JSON Schema

{
  "name"      : "long",
  "properties":
  {
    "long":
    {
      "description": "A long integer value",
      "type"       : "integer",
      "required"   : true
    }
  }
}

See also: RENEWDELEGATIONTOKEN,

Path JSON Schema

{
  "name"      : "Path",
  "properties":
  {
    "Path":
    {
      "description": "The string representation a Path.",
      "type"       : "string",
      "required"   : true
    }
  }
}

See also: GETHOMEDIRECTORY, Path

RemoteException JSON Schema

{
  "name"      : "RemoteException",
  "properties":
  {
    "RemoteException":
    {
      "type"      : "object",
      "properties":
      {
        "exception":
        {
          "description": "Name of the exception",
          "type"       : "string",
          "required"   : true
        },
        "message":
        {
          "description": "Exception message",
          "type"       : "string",
          "required"   : true
        },
        "javaClassName":                                     //an optional property
        {
          "description": "Java class name of the exception",
          "type"       : "string"
        }
      }
    }
  }
}

See also: Error Responses

Token JSON Schema

{
  "name"      : "Token",
  "properties":
  {
    "Token": tokenProperties      //See Token Properties
  }
}

See also: Token Properties, GETDELEGATIONTOKEN, the note in Delegation.

Token Properties

JavaScript syntax is used to define tokenProperties so that it can be referred in Token JSON schema.

var tokenProperties =
{
  "type"      : "object",
  "properties":
  {
    "urlString":
    {
      "description": "A delegation token encoded as a URL safe string.",
      "type"       : "string",
      "required"   : true
    }
  }
}

See also: Token Properties, the note in Delegation.

BlockStoragePolicy JSON Schema

{
  "name"      : "BlockStoragePolicy",
  "properties":
  {
    "BlockStoragePolicy": blockStoragePolicyProperties      //See BlockStoragePolicy Properties
  }
}

See also: BlockStoragePolicy Properties, GETSTORAGEPOLICY

BlockStoragePolicy Properties

JavaScript syntax is used to define blockStoragePolicyProperties so that it can be referred in both BlockStoragePolicy and BlockStoragePolicies JSON schemas.

var blockStoragePolicyProperties =
{
  "type"      : "object",
  "properties":
  {
    "id":
    {
      "description": "Policy ID.",
      "type"       : "integer",
      "required"   : true
    },
    "name":
    {
      "description": "Policy name.",
      "type"       : "string",
      "required"   : true
    },
    "storageTypes":
    {
      "description": "An array of storage types for block placement.",
      "type"       : "array",
      "required"   : true
      "items"      :
      {
        "type": "string"
      }
    },
    "replicationFallbacks":
    {
      "description": "An array of fallback storage types for replication.",
      "type"       : "array",
      "required"   : true
      "items"      :
      {
        "type": "string"
      }
    },
    "creationFallbacks":
    {
      "description": "An array of fallback storage types for file creation.",
      "type"       : "array",
      "required"   : true
      "items"      :
      {
       "type": "string"
      }
    },
    "copyOnCreateFile":
    {
      "description": "If set then the policy cannot be changed after file creation.",
      "type"       : "boolean",
      "required"   : true
    }
  }
};

BlockStoragePolicies JSON Schema

A BlockStoragePolicies JSON object represents an array of BlockStoragePolicy JSON objects.

{
  "name"      : "BlockStoragePolicies",
  "properties":
  {
    "BlockStoragePolicies":
    {
      "type"      : "object",
      "properties":
      {
        "BlockStoragePolicy":
        {
          "description": "An array of BlockStoragePolicy",
          "type"       : "array",
          "items"      : blockStoragePolicyProperties      //See BlockStoragePolicy Properties
        }
      }
    }
  }
}

HTTP Query Parameter Dictionary

ACL Spec

Name aclspec
Description The ACL spec included in ACL modification operations.
Type String
Default Value <empty>
Valid Values See Permissions and HDFS.
Syntax See Permissions and HDFS.

XAttr Name

Name xattr.name
Description The XAttr name of a file/directory.
Type String
Default Value <empty>
Valid Values Any string prefixed with user./trusted./system./security..
Syntax Any string prefixed with user./trusted./system./security..

XAttr Value

Name xattr.value
Description The XAttr value of a file/directory.
Type String
Default Value <empty>
Valid Values An encoded value.
Syntax Enclosed in double quotes or prefixed with 0x or 0s.

See also: Extended Attributes

XAttr set flag

Name flag
Description The XAttr set flag.
Type String
Default Value <empty>
Valid Values CREATE,REPLACE.
Syntax CREATE,REPLACE.

See also: Extended Attributes

XAttr value encoding

Name encoding
Description The XAttr value encoding.
Type String
Default Value <empty>
Valid Values text hex base64
Syntax text hex base64

See also: Extended Attributes

Access Time

Name accesstime
Description The access time of a file/directory.
Type long
Default Value -1 (means keeping it unchanged)
Valid Values -1 or a timestamp
Syntax Any integer.

See also: SETTIMES

Block Size

Name blocksize
Description The block size of a file.
Type long
Default Value Specified in the configuration.
Valid Values > 0
Syntax Any integer.

See also: CREATE

Buffer Size

Name buffersize
Description The size of the buffer used in transferring data.
Type int
Default Value Specified in the configuration.
Valid Values > 0
Syntax Any integer.

See also: CREATE, APPEND, OPEN

Create Flag

Name createflag
Description Enum of possible flags to process while creating a file
Type enumerated strings
Default Value <empty>
Valid Values Legal combinations of create, overwrite, append and sync_block
Syntax See note below

The following combinations are not valid: * append,create * create,append,overwrite

See also: CREATE

Create Parent

Name createparent
Description If the parent directories do not exist, should they be created?
Type boolean
Default Value true
Valid Values true, false
Syntax true

See also: CREATESYMLINK

Delegation

Name delegation
Description The delegation token used for authentication.
Type String
Default Value <empty>
Valid Values An encoded token.
Syntax See the note below.

Note that delegation tokens are encoded as a URL safe string; see encodeToUrlString() and decodeFromUrlString(String) in org.apache.hadoop.security.token.Token for the details of the encoding.

See also: Authentication

Destination

Name destination
Description The destination path.
Type Path
Default Value <empty> (an invalid path)
Valid Values An absolute FileSystem path without scheme and authority.
Syntax Any path.

See also: CREATESYMLINK, RENAME

Do As

Name doas
Description Allowing a proxy user to do as another user.
Type String
Default Value null
Valid Values Any valid username.
Syntax Any string.

See also: Proxy Users

Fs Action

Name fsaction
Description File system operation read/write/execute
Type String
Default Value null (an invalid value)
Valid Values Strings matching regex pattern  “[r-][w-][x-] ”
Syntax  “[r-][w-][x-] ”

See also: CHECKACCESS,

Group

Name group
Description The name of a group.
Type String
Default Value <empty> (means keeping it unchanged)
Valid Values Any valid group name.
Syntax Any string.

See also: SETOWNER

Length

Name length
Description The number of bytes to be processed.
Type long
Default Value null (means the entire file)
Valid Values >= 0 or null
Syntax Any integer.

See also: OPEN

Modification Time

Name modificationtime
Description The modification time of a file/directory.
Type long
Default Value -1 (means keeping it unchanged)
Valid Values -1 or a timestamp
Syntax Any integer.

See also: SETTIMES

New Length

Name newlength
Description The size the file is to be truncated to.
Type long
Valid Values >= 0
Syntax Any long.

Offset

Name offset
Description The starting byte position.
Type long
Default Value 0
Valid Values >= 0
Syntax Any integer.

See also: OPEN

Old Snapshot Name

Name oldsnapshotname
Description The old name of the snapshot to be renamed.
Type String
Default Value null
Valid Values An existing snapshot name.
Syntax Any string.

See also: RENAMESNAPSHOT

Op

Name op
Description The name of the operation to be executed.
Type enum
Default Value null (an invalid value)
Valid Values Any valid operation name.
Syntax Any string.

See also: Operations

Overwrite

Name overwrite
Description If a file already exists, should it be overwritten?
Type boolean
Default Value false
Valid Values true
Syntax true

See also: CREATE

Owner

Name owner
Description The username who is the owner of a file/directory.
Type String
Default Value <empty> (means keeping it unchanged)
Valid Values Any valid username.
Syntax Any string.

See also: SETOWNER

Permission

Name permission
Description The permission of a file/directory.
Type Octal
Default Value 755
Valid Values 0 - 1777
Syntax Any radix-8 integer (leading zeros may be omitted.)

See also: CREATE, MKDIRS, SETPERMISSION

Recursive

Name recursive
Description Should the operation act on the content in the subdirectories?
Type boolean
Default Value false
Valid Values true
Syntax true

See also: RENAME

Renewer

Name renewer
Description The username of the renewer of a delegation token.
Type String
Default Value <empty> (means the current user)
Valid Values Any valid username.
Syntax Any string.

See also: GETDELEGATIONTOKEN

Replication

Name replication
Description The number of replications of a file.
Type short
Default Value Specified in the configuration.
Valid Values > 0
Syntax Any integer.

See also: CREATE, SETREPLICATION

Snapshot Name

Name snapshotname
Description The name of the snapshot to be created/deleted. Or the new name for snapshot rename.
Type String
Default Value null
Valid Values Any valid snapshot name.
Syntax Any string.

See also: CREATESNAPSHOT, DELETESNAPSHOT, RENAMESNAPSHOT

Sources

Name sources
Description A list of source paths.
Type String
Default Value <empty>
Valid Values A list of comma seperated absolute FileSystem paths without scheme and authority.
Syntax Any string.

See also: CONCAT

Token

Name token
Description The delegation token used for the operation.
Type String
Default Value <empty>
Valid Values An encoded token.
Syntax See the note in Delegation.

See also: RENEWDELEGATIONTOKEN, CANCELDELEGATIONTOKEN

Token Kind

Name kind
Description The kind of the delegation token requested
Type String
Default Value <empty> (Server sets the default kind for the service)
Valid Values A string that represents token kind e.g “HDFS_DELEGATION_TOKEN” or “WEBHDFS delegation”
Syntax Any string.

See also: GETDELEGATIONTOKEN

Token Service

Name service
Description The name of the service where the token is supposed to be used, e.g. ip:port of the namenode
Type String
Default Value <empty>
Valid Values ip:port in string format or logical name of the service
Syntax Any string.

See also: GETDELEGATIONTOKEN

Username

Name user.name
Description The authenticated user; see Authentication.
Type String
Default Value null
Valid Values Any valid username.
Syntax Any string.

See also: Authentication

Storage Policy

Name storagepolicy
Description The name of the storage policy.
Type String
Default Value <empty>
Valid Values Any valid storage policy name; see GETALLSTORAGEPOLICY.
Syntax Any string.

See also: SETSTORAGEPOLICY