User Data

User data is a key/value store you can use to provide your instance with introspective data.

As an example of use, Scaleway images contain the scw-generate-ssh-keys script, which generates the SSH server’s host keys, then stores their fingerprints as user data under the ssh-host-fingerprints key. This way, before connecting to the instance using SSH, one can query the fingerprints to ensure that the remote host is the expected one, thus avoiding any man-in-the-middle attack.

There are two ways of accessing user data:

• From within a running Instance, by requesting the Metadata API at http://169.254.42.42/user_dataOpen in new context (or http://[fd00:42::42]/user_data using IPv6). The scaleway-ecosystem package, installed by default on all OS images provided by Scaleway, ships with the scw-userdata helper command that allows you to easily query the user data from the instance. For security reasons, viewing and editing user data is only allowed to queries originating from a port below 1024 (by default, only the super-user can bind to ports below 1024). To specify the source port with cURL, use the --local-port option (e.g. curl --local-port 1-1023 http://169.254.42.42/user_data).
• From the Instance API by using the methods described below.