d63afbf6c5
The API reference for the "user_data" parameter to server create and rebuild mentions the size restriction but the user docs did not, so this adds that note. While doing this, several other user-facing docs that mention user data link back to the overall user-data doc so that we can centralize any further documentation about that topic in a single location. Change-Id: Id4a61d58150337e0dec223d4d2741336ed6d5387 Closes-Bug: #1804653
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974 B
ReStructuredText
26 lines
974 B
ReStructuredText
==============================
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Provide user data to instances
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==============================
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*User data* is a blob of data that the user can specify when they launch an
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instance. The instance can access this data through the metadata service or
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config drive. Commonly used to pass a shell script that the instance runs on
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boot.
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For example, one application that uses user data is the
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`cloud-init <https://help.ubuntu.com/community/CloudInit>`__ system,
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which is an open-source package from Ubuntu that is available on various
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Linux distributions and which handles early initialization of a cloud
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instance.
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You can place user data in a local file and pass it through the
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``--user-data <user-data-file>`` parameter at instance creation.
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.. code-block:: console
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$ openstack server create --image ubuntu-cloudimage --flavor 1 \
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--user-data mydata.file VM_INSTANCE
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.. note:: The provided user data must be base64 encoded and is restricted to
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65535 bytes.
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