201 lines
6.6 KiB
ReStructuredText
201 lines
6.6 KiB
ReStructuredText
=================
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Object versioning
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=================
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You can store multiple versions of your content so that you can recover
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from unintended overwrites. Object versioning is an easy way to
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implement version control, which you can use with any type of content.
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.. note::
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You cannot version a large-object manifest file, but the large-object
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manifest file can point to versioned segments.
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We strongly recommend that you put non-current objects in a different
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container than the container where current object versions reside.
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To enable and use object versioning
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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#. To enable object versioning, ask your cloud provider to set the
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``allow_versions`` option to ``TRUE`` in the container configuration
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file.
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#. Create an ``archive`` container to store older versions of objects:
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.. code-block:: console
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$ curl -i $publicURL/archive -X PUT -H "Content-Length: 0" -H "X-Auth-Token: $token"
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.. code-block:: console
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HTTP/1.1 201 Created
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Content-Length: 0
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Content-Type: text/html; charset=UTF-8
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X-Trans-Id: tx46f8c29050834d88b8d7e-0052e1859d
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Date: Thu, 23 Jan 2014 21:11:57 GMT
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#. Create a ``current`` container to store current versions of objects.
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Include the ``X-Versions-Location`` header. This header defines the
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container that holds the non-current versions of your objects. You
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must UTF-8-encode and then URL-encode the container name before you
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include it in the ``X-Versions-Location`` header. This header enables
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object versioning for all objects in the ``current`` container.
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Changes to objects in the ``current`` container automatically create
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non-current versions in the ``archive`` container.
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.. code-block:: console
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$ curl -i $publicURL/current -X PUT -H "Content-Length: 0" -H \
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”X-Auth-Token: $token" -H "X-Versions-Location: archive"
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.. code-block:: console
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HTTP/1.1 201 Created
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Content-Length: 0
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Content-Type: text/html; charset=UTF-8
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X-Trans-Id: txb91810fb717347d09eec8-0052e18997
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Date: Thu, 23 Jan 2014 21:28:55 GMT
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#. Create the first version of an object in the ``current`` container:
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.. code-block:: console
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$ curl -i $publicURL/current/my_object --data-binary 1 -X PUT -H \
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”Content-Length: 0" -H "X-Auth-Token: $token"
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.. code-block:: console
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HTTP/1.1 201 Created
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Last-Modified: Thu, 23 Jan 2014 21:31:22 GMT
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Content-Length: 0
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Etag: d41d8cd98f00b204e9800998ecf8427e
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Content-Type: text/html; charset=UTF-8
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X-Trans-Id: tx5992d536a4bd4fec973aa-0052e18a2a
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Date: Thu, 23 Jan 2014 21:31:22 GMT
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Nothing is written to the non-current version container when you
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initially ``PUT`` an object in the ``current`` container. However,
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subsequent ``PUT`` requests that edit an object trigger the creation
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of a version of that object in the ``archive`` container.
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These non-current versions are named as follows:
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.. code-block:: console
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<length><object_name><timestamp>
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Where ``length`` is the 3-character, zero-padded hexadecimal
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character length of the object, ``<object_name>`` is the object name,
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and ``<timestamp>`` is the time when the object was initially created
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as a current version.
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#. Create a second version of the object in the ``current`` container:
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.. code-block:: console
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$ curl -i $publicURL/current/my_object --data-binary 2 -X PUT -H \
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“Content-Length: 0" -H "X-Auth-Token: $token"
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.. code-block:: console
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HTTP/1.1 201 Created
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Last-Modified: Thu, 23 Jan 2014 21:41:32 GMT
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Content-Length: 0
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Etag: d41d8cd98f00b204e9800998ecf8427e
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Content-Type: text/html; charset=UTF-8
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X-Trans-Id: tx468287ce4fc94eada96ec-0052e18c8c
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Date: Thu, 23 Jan 2014 21:41:32 GMT
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#. Issue a ``GET`` request to a versioned object to get the current
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version of the object. You do not have to do any request redirects or
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metadata lookups.
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List older versions of the object in the ``archive`` container:
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.. code-block:: console
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$ curl -i $publicURL/archive?prefix=009my_object -X GET -H \
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"X-Auth-Token: $token"
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.. code-block:: console
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HTTP/1.1 200 OK
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Content-Length: 30
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X-Container-Object-Count: 1
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Accept-Ranges: bytes
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X-Timestamp: 1390513280.79684
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X-Container-Bytes-Used: 0
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Content-Type: text/plain; charset=utf-8
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X-Trans-Id: tx9a441884997542d3a5868-0052e18d8e
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Date: Thu, 23 Jan 2014 21:45:50 GMT
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009my_object/1390512682.92052
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.. note::
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A ``POST`` request to a versioned object updates only the metadata
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for the object and does not create a new version of the object. New
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versions are created only when the content of the object changes.
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#. Issue a ``DELETE`` request to a versioned object to remove the
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current version of the object and replace it with the next-most
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current version in the non-current container.
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.. code-block:: console
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$ curl -i $publicURL/current/my_object -X DELETE -H \
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"X-Auth-Token: $token"
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.. code-block:: console
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HTTP/1.1 204 No Content
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Content-Length: 0
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Content-Type: text/html; charset=UTF-8
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X-Trans-Id: tx006d944e02494e229b8ee-0052e18edd
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Date: Thu, 23 Jan 2014 21:51:25 GMT
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List objects in the ``archive`` container to show that the archived
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object was moved back to the ``current`` container:
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.. code-block:: console
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$ curl -i $publicURL/archive?prefix=009my_object -X GET -H \
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"X-Auth-Token: $token"
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.. code-block:: console
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HTTP/1.1 204 No Content
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Content-Length: 0
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X-Container-Object-Count: 0
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Accept-Ranges: bytes
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X-Timestamp: 1390513280.79684
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X-Container-Bytes-Used: 0
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Content-Type: text/html; charset=UTF-8
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X-Trans-Id: tx044f2a05f56f4997af737-0052e18eed
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Date: Thu, 23 Jan 2014 21:51:41 GMT
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This next-most current version carries with it any metadata last set
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on it. If you want to completely remove an object and you have five
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versions of it, you must ``DELETE`` it five times.
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#. To disable object versioning for the ``current`` container, remove
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its ``X-Versions-Location`` metadata header by sending an empty key
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value.
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.. code-block:: console
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$ curl -i $publicURL/current -X PUT -H "Content-Length: 0" -H \
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"X-Auth-Token: $token" -H "X-Versions-Location: "
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.. code-block:: console
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HTTP/1.1 202 Accepted
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Content-Length: 76
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Content-Type: text/html; charset=UTF-8
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X-Trans-Id: txe2476de217134549996d0-0052e19038
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Date: Thu, 23 Jan 2014 21:57:12 GMT
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<html><h1>Accepted</h1><p>The request is accepted for processing.</p></html>
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