ceph/doc/radosgw/nfs.rst

   1 ===
   2 NFS
   3 ===
   4
   5 .. versionadded:: Jewel
   6
   7 .. note:: Only the NFSv4 protocol is supported when using a cephadm or rook based deployment.
   8
   9 Ceph Object Gateway namespaces can be exported over the file-based
  10 NFSv4 protocols, alongside traditional HTTP access
  11 protocols (S3 and Swift).
  12
  13 In particular, the Ceph Object Gateway can now be configured to
  14 provide file-based access when embedded in the NFS-Ganesha NFS server.
  15
  16 The simplest and preferred way of managing nfs-ganesha clusters and rgw exports
  17 is using ``ceph nfs ...`` commands. See :doc:`/mgr/nfs` for more details.
  18
  19 librgw
  20 ======
  21
  22 The librgw.so shared library (Unix) provides a loadable interface to
  23 Ceph Object Gateway services, and instantiates a full Ceph Object Gateway
  24 instance on initialization.
  25
  26 In turn, librgw.so exports rgw_file, a stateful API for file-oriented
  27 access to RGW buckets and objects.  The API is general, but its design
  28 is strongly influenced by the File System Abstraction Layer (FSAL) API
  29 of NFS-Ganesha, for which it has been primarily designed.
  30
  31 A set of Python bindings is also provided.
  32
  33 Namespace Conventions
  34 =====================
  35
  36 The implementation conforms to Amazon Web Services (AWS) hierarchical
  37 namespace conventions which map UNIX-style path names onto S3 buckets
  38 and objects.
  39
  40 The top level of the attached namespace consists of S3 buckets,
  41 represented as NFS directories. Files and directories subordinate to
  42 buckets are each represented as objects, following S3 prefix and
  43 delimiter conventions, with '/' being the only supported path
  44 delimiter [#]_.
  45
  46 For example, if an NFS client has mounted an RGW namespace at "/nfs",
  47 then a file "/nfs/mybucket/www/index.html" in the NFS namespace
  48 corresponds to an RGW object "www/index.html" in a bucket/container
  49 "mybucket."
  50
  51 Although it is generally invisible to clients, the NFS namespace is
  52 assembled through concatenation of the corresponding paths implied by
  53 the objects in the namespace.  Leaf objects, whether files or
  54 directories, will always be materialized in an RGW object of the
  55 corresponding key name, "<name>" if a file, "<name>/" if a directory.
  56 Non-leaf directories (e.g., "www" above) might only be implied by
  57 their appearance in the names of one or more leaf objects. Directories
  58 created within NFS or directly operated on by an NFS client (e.g., via
  59 an attribute-setting operation such as chown or chmod) always have a
  60 leaf object representation used to store materialized attributes such
  61 as Unix ownership and permissions.
  62
  63 Supported Operations
  64 ====================
  65
  66 The RGW NFS interface supports most operations on files and
  67 directories, with the following restrictions:
  68
  69 - Links, including symlinks, are not supported.
  70 - NFS ACLs are not supported.
  71
  72   + Unix user and group ownership and permissions *are* supported.
  73
  74 - Directories may not be moved/renamed.
  75
  76   + Files may be moved between directories.
  77
  78 - Only full, sequential *write* I/O is supported
  79
  80   + i.e., write operations are constrained to be **uploads**.
  81   + Many typical I/O operations such as editing files in place will necessarily fail as they perform non-sequential stores.
  82   + Some file utilities *apparently* writing sequentially (e.g., some versions of GNU tar) may fail due to infrequent non-sequential stores.
  83   + When mounting via NFS, sequential application I/O can generally be constrained to be written sequentially to the NFS server via a synchronous mount option (e.g. -osync in Linux).
  84   + NFS clients which cannot mount synchronously (e.g., MS Windows) will not be able to upload files.
  85
  86 Security
  87 ========
  88
  89 The RGW NFS interface provides a hybrid security model with the
  90 following characteristics:
  91
  92 - NFS protocol security is provided by the NFS-Ganesha server, as negotiated by the NFS server and clients
  93
  94   + e.g., clients can by trusted (AUTH_SYS), or required to present Kerberos user credentials (RPCSEC_GSS)
  95   + RPCSEC_GSS wire security can be integrity only (krb5i) or integrity and privacy (encryption, krb5p)
  96   + various NFS-specific security and permission rules are available
  97
  98     * e.g., root-squashing
  99
 100 - a set of RGW/S3 security credentials (unknown to NFS) is associated with each RGW NFS mount (i.e., NFS-Ganesha EXPORT)
 101
 102   + all RGW object operations performed via the NFS server will be performed by the RGW user associated with the credentials stored in the export being accessed (currently only RGW and RGW LDAP credentials are supported)
 103
 104     * additional RGW authentication types such as Keystone are not currently supported
 105
 106 Manually configuring an NFS-Ganesha Instance
 107 ============================================
 108
 109 Each NFS RGW instance is an NFS-Ganesha server instance *embeddding*
 110 a full Ceph RGW instance.
 111
 112 Therefore, the RGW NFS configuration includes Ceph and Ceph Object
 113 Gateway-specific configuration in a local ceph.conf, as well as
 114 NFS-Ganesha-specific configuration in the NFS-Ganesha config file,
 115 ganesha.conf.
 116
 117 ceph.conf
 118 ---------
 119
 120 Required ceph.conf configuration for RGW NFS includes:
 121
 122 * valid [client.radosgw.{instance-name}] section
 123 * valid values for minimal instance configuration, in particular, an installed and correct ``keyring``
 124
 125 Other config variables are optional, front-end-specific and front-end
 126 selection variables (e.g., ``rgw data`` and ``rgw frontends``) are
 127 optional and in some cases ignored.
 128
 129 A small number of config variables (e.g., ``rgw_nfs_namespace_expire_secs``)
 130 are unique to RGW NFS.
 131
 132 ganesha.conf
 133 ------------
 134
 135 A strictly minimal ganesha.conf for use with RGW NFS includes one
 136 EXPORT block with embedded FSAL block of type RGW::
 137
 138    EXPORT
 139    {
 140         Export_ID={numeric-id};
 141         Path = "/";
 142         Pseudo = "/";
 143         Access_Type = RW;
 144         SecType = "sys";
 145         NFS_Protocols = 4;
 146         Transport_Protocols = TCP;
 147
 148         # optional, permit unsquashed access by client "root" user
 149         #Squash = No_Root_Squash;
 150
 151         FSAL {
 152                 Name = RGW;
 153                 User_Id = {s3-user-id};
 154                 Access_Key_Id ="{s3-access-key}";
 155                 Secret_Access_Key = "{s3-secret}";
 156         }
 157    }
 158
 159 ``Export_ID`` must have an integer value, e.g., "77"
 160
 161 ``Path`` (for RGW) should be "/"
 162
 163 ``Pseudo`` defines an NFSv4 pseudo root name (NFSv4 only)
 164
 165 ``SecType = sys;`` allows clients to attach without Kerberos
 166 authentication
 167
 168 ``Squash = No_Root_Squash;`` enables the client root user to override
 169 permissions (Unix convention).  When root-squashing is enabled,
 170 operations attempted by the root user are performed as if by the local
 171 "nobody" (and "nogroup") user on the NFS-Ganesha server
 172
 173 The RGW FSAL additionally supports RGW-specific configuration
 174 variables in the RGW config section::
 175
 176  RGW {
 177      cluster = "{cluster name, default 'ceph'}";
 178      name = "client.rgw.{instance-name}";
 179      ceph_conf = "/opt/ceph-rgw/etc/ceph/ceph.conf";
 180      init_args = "-d --debug-rgw=16";
 181  }
 182
 183 ``cluster`` sets a Ceph cluster name (must match the cluster being exported)
 184
 185 ``name`` sets an RGW instance name (must match the cluster being exported)
 186
 187 ``ceph_conf`` gives a path to a non-default ceph.conf file to use
 188
 189
 190 Other useful NFS-Ganesha configuration:
 191 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 192
 193 Any EXPORT block which should support NFSv3 should include version 3
 194 in the NFS_Protocols setting. Additionally, NFSv3 is the last major
 195 version to support the UDP transport. To enable UDP, include it in the
 196 Transport_Protocols setting. For example::
 197
 198  EXPORT {
 199   ...
 200     NFS_Protocols = 3,4;
 201     Transport_Protocols = UDP,TCP;
 202   ...
 203  }
 204
 205 One important family of options pertains to interaction with the Linux
 206 idmapping service, which is used to normalize user and group names
 207 across systems.  Details of idmapper integration are not provided here.
 208
 209 With Linux NFS clients, NFS-Ganesha can be configured
 210 to accept client-supplied numeric user and group identifiers with
 211 NFSv4, which by default stringifies these--this may be useful in small
 212 setups and for experimentation::
 213
 214  NFSV4 {
 215      Allow_Numeric_Owners = true;
 216      Only_Numeric_Owners = true;
 217  }
 218
 219 Troubleshooting
 220 ~~~~~~~~~~~~~~~
 221
 222 NFS-Ganesha configuration problems are usually debugged by running the
 223 server with debugging options, controlled by the LOG config section.
 224
 225 NFS-Ganesha log messages are grouped into various components, logging
 226 can be enabled separately for each component. Valid values for
 227 component logging include::
 228
 229   *FATAL* critical errors only
 230   *WARN* unusual condition
 231   *DEBUG* mildly verbose trace output
 232   *FULL_DEBUG* verbose trace output
 233
 234 Example::
 235
 236   LOG {
 237
 238         Components {
 239                 MEMLEAKS = FATAL;
 240                 FSAL = FATAL;
 241                 NFSPROTO = FATAL;
 242                 NFS_V4 = FATAL;
 243                 EXPORT = FATAL;
 244                 FILEHANDLE = FATAL;
 245                 DISPATCH = FATAL;
 246                 CACHE_INODE = FATAL;
 247                 CACHE_INODE_LRU = FATAL;
 248                 HASHTABLE = FATAL;
 249                 HASHTABLE_CACHE = FATAL;
 250                 DUPREQ = FATAL;
 251                 INIT = DEBUG;
 252                 MAIN = DEBUG;
 253                 IDMAPPER = FATAL;
 254                 NFS_READDIR = FATAL;
 255                 NFS_V4_LOCK = FATAL;
 256                 CONFIG = FATAL;
 257                 CLIENTID = FATAL;
 258                 SESSIONS = FATAL;
 259                 PNFS = FATAL;
 260                 RW_LOCK = FATAL;
 261                 NLM = FATAL;
 262                 RPC = FATAL;
 263                 NFS_CB = FATAL;
 264                 THREAD = FATAL;
 265                 NFS_V4_ACL = FATAL;
 266                 STATE = FATAL;
 267                 FSAL_UP = FATAL;
 268                 DBUS = FATAL;
 269         }
 270         # optional: redirect log output
 271  #      Facility {
 272  #              name = FILE;
 273  #              destination = "/tmp/ganesha-rgw.log";
 274  #              enable = active;
 275         }
 276  }
 277
 278 Running Multiple NFS Gateways
 279 =============================
 280
 281 Each NFS-Ganesha instance acts as a full gateway endpoint, with the
 282 limitation that currently an NFS-Ganesha instance cannot be configured
 283 to export HTTP services. As with ordinary gateway instances, any
 284 number of NFS-Ganesha instances can be started, exporting the same or
 285 different resources from the cluster. This enables the clustering of
 286 NFS-Ganesha instances. However, this does not imply high availability.
 287
 288 When regular gateway instances and NFS-Ganesha instances overlap the
 289 same data resources, they will be accessible from both the standard S3
 290 API and through the NFS-Ganesha instance as exported. You can
 291 co-locate the NFS-Ganesha instance with a Ceph Object Gateway instance
 292 on the same host.
 293
 294 RGW vs RGW NFS
 295 ==============
 296
 297 Exporting an NFS namespace and other RGW namespaces (e.g., S3 or Swift
 298 via the Civetweb HTTP front-end) from the same program instance is
 299 currently not supported.
 300
 301 When adding objects and buckets outside of NFS, those objects will
 302 appear in the NFS namespace in the time set by
 303 ``rgw_nfs_namespace_expire_secs``, which defaults to 300 seconds (5 minutes).
 304 Override the default value for ``rgw_nfs_namespace_expire_secs`` in the
 305 Ceph configuration file to change the refresh rate.
 306
 307 If exporting Swift containers that do not conform to valid S3 bucket
 308 naming requirements, set ``rgw_relaxed_s3_bucket_names`` to true in the
 309 [client.radosgw] section of the Ceph configuration file. For example,
 310 if a Swift container name contains underscores, it is not a valid S3
 311 bucket name and will be rejected unless ``rgw_relaxed_s3_bucket_names``
 312 is set to true.
 313
 314 Configuring NFSv4 clients
 315 =========================
 316
 317 To access the namespace, mount the configured NFS-Ganesha export(s)
 318 into desired locations in the local POSIX namespace. As noted, this
 319 implementation has a few unique restrictions:
 320
 321 - NFS 4.1 and higher protocol flavors are preferred
 322
 323   + NFSv4 OPEN and CLOSE operations are used to track upload transactions
 324
 325 - To upload data successfully, clients must preserve write ordering
 326
 327   + on Linux and many Unix NFS clients, use the -osync mount option
 328
 329 Conventions for mounting NFS resources are platform-specific. The
 330 following conventions work on Linux and some Unix platforms:
 331
 332 From the command line::
 333
 334   mount -t nfs -o nfsvers=4.1,noauto,soft,sync,proto=tcp <ganesha-host-name>:/ <mount-point>
 335
 336 In /etc/fstab::
 337
 338 <ganesha-host-name>:/ <mount-point> nfs noauto,soft,nfsvers=4.1,sync,proto=tcp 0 0
 339
 340 Specify the NFS-Ganesha host name and the path to the mount point on
 341 the client.
 342
 343 Configuring NFSv3 Clients
 344 =========================
 345
 346 Linux clients can be configured to mount with NFSv3 by supplying
 347 ``nfsvers=3`` and ``noacl`` as mount options. To use UDP as the
 348 transport, add ``proto=udp`` to the mount options. However, TCP is the
 349 preferred transport::
 350
 351   <ganesha-host-name>:/ <mount-point> nfs noauto,noacl,soft,nfsvers=3,sync,proto=tcp 0 0
 352
 353 Configure the NFS Ganesha EXPORT block Protocols setting with version
 354 3 and the Transports setting with UDP if the mount will use version 3 with UDP.
 355
 356 NFSv3 Semantics
 357 ---------------
 358
 359 Since NFSv3 does not communicate client OPEN and CLOSE operations to
 360 file servers, RGW NFS cannot use these operations to mark the
 361 beginning and ending of file upload transactions. Instead, RGW NFS
 362 starts a new upload when the first write is sent to a file at offset
 363 0, and finalizes the upload when no new writes to the file have been
 364 seen for a period of time, by default, 10 seconds. To change this
 365 timeout, set an alternate value for ``rgw_nfs_write_completion_interval_s``
 366 in the RGW section(s) of the Ceph configuration file.
 367
 368 References
 369 ==========
 370
 371 .. [#] http://docs.aws.amazon.com/AmazonS3/latest/dev/ListingKeysHierarchy.html