openstack/nova
Code Issues Proposed changes
nova/doc/source/user/user-data.rst
Matt Riedemann d63afbf6c5 Mention size limit on user data in docs 
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
2018-11-30 10:07:08 -05:00

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Provide user data to instances

User data is a blob of data that the user can specify when they launch an instance. The instance can access this data through the metadata service or config drive. Commonly used to pass a shell script that the instance runs on boot.

For example, one application that uses user data is the cloud-init system, which is an open-source package from Ubuntu that is available on various Linux distributions and which handles early initialization of a cloud instance.

You can place user data in a local file and pass it through the --user-data <user-data-file> parameter at instance creation.

$ openstack server create --image ubuntu-cloudimage --flavor 1 \
  --user-data mydata.file VM_INSTANCE

Note

The provided user data must be base64 encoded and is restricted to 65535 bytes.