90 lines
3.5 KiB
ReStructuredText
90 lines
3.5 KiB
ReStructuredText
=================
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Object Versioning
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=================
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--------
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Overview
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--------
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Object versioning in swift is implemented by setting a flag on the container
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to tell swift to version all objects in the container. The flag is the
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``X-Versions-Location`` header on the container, and its value is the
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container where the versions are stored. It is recommended to use a different
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``X-Versions-Location`` container for each container that is being versioned.
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When data is ``PUT`` into a versioned container (a container with the
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versioning flag turned on), the existing data in the file is redirected to a
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new object and the data in the ``PUT`` request is saved as the data for the
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versioned object. The new object name (for the previous version) is
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``<versions_container>/<length><object_name>/<timestamp>``, where ``length``
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is the 3-character zero-padded hexadecimal length of the ``<object_name>`` and
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``<timestamp>`` is the timestamp of when the previous version was created.
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A ``GET`` to a versioned object will return the current version of the object
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without having to do any request redirects or metadata lookups.
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A ``POST`` to a versioned object will update the object metadata as normal,
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but will not create a new version of the object. In other words, new versions
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are only created when the content of the object changes.
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A ``DELETE`` to a versioned object will only remove the current version of the
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object. If you have 5 total versions of the object, you must delete the
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object 5 times to completely remove the object.
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Note: A large object manifest file cannot be versioned, but a large object
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manifest may point to versioned segments.
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--------------------------------------------------
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How to Enable Object Versioning in a Swift Cluster
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--------------------------------------------------
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Set ``allow_versions`` to ``True`` in the container server config.
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-----------------------
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Examples Using ``curl``
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-----------------------
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First, create a container with the ``X-Versions-Location`` header or add the
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header to an existing container. Also make sure the container referenced by
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the ``X-Versions-Location`` exists. In this example, the name of that
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container is "versions"::
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curl -i -XPUT -H "X-Auth-Token: <token>" \
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-H "X-Versions-Location: versions" http://<storage_url>/container
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curl -i -XPUT -H "X-Auth-Token: <token>" http://<storage_url>/versions
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Create an object (the first version)::
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curl -i -XPUT --data-binary 1 -H "X-Auth-Token: <token>" \
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http://<storage_url>/container/myobject
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Now create a new version of that object::
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curl -i -XPUT --data-binary 2 -H "X-Auth-Token: <token>" \
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http://<storage_url>/container/myobject
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See a listing of the older versions of the object::
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curl -i -H "X-Auth-Token: <token>" \
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http://<storage_url>/versions?prefix=008myobject/
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Now delete the current version of the object and see that the older version is
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gone::
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curl -i -XDELETE -H "X-Auth-Token: <token>" \
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http://<storage_url>/container/myobject
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curl -i -H "X-Auth-Token: <token>" \
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http://<storage_url>/versions?prefix=008myobject/
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---------------------------------------------------
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How to Disable Object Versioning in a Swift Cluster
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---------------------------------------------------
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If you want to disable all functionality, set ``allow_versions`` back to
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``False`` in the container server config.
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Disable versioning a versioned container (x is any value except empty)::
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curl -i -XPOST -H "X-Auth-Token: <token>" \
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-H "X-Remove-Versions-Location: x" http://<storage_url>/container
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