Provide user data to instances

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


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

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