This isn't documented. It's really not intended for users to be overriding things defined in cloud.cfg, but it happens enough that we should document it.
On your cloud instance, /etc/cloud/cloud.cfg (and anything in the .d directory) specifies what cloud-init modules are run and in what stage of cloud-init. More about stages and modules at: https://cloudinit.readthedocs.io/en/latest/topics/boot.html https://cloudinit.readthedocs.io/en/latest/topics/modules.html The "once" in the example you listed is frequency. It specifies when a module should be run. Some modules are run every single boot, some only once per instance, and others only once ever. Valid frequencies are "once", "once-per-instance", and "always". By default, users-groups is run once per instance, so this is instructing cloud-init to run this snippet only once. It's a way of using cloud-init to get a key into the instance as a one-time thing. On Tue, Sep 28, 2021 at 10:50 PM Yuri Kanivetsky <[email protected]> wrote: > > Hi, > > I've run into the following... what do you call it? piece of user data? > > Content-Type: multipart/mixed; boundary="//" > MIME-Version: 1.0 > > --// > Content-Type: text/cloud-config; charset="us-ascii" > MIME-Version: 1.0 > Content-Transfer-Encoding: 7bit > Content-Disposition: attachment; filename="cloud-config.txt" > > #cloud-config > cloud_final_modules: > - [users-groups, once] > users: > - name: username > ssh-authorized-keys: > - PublicKeypair > > https://aws.amazon.com/premiumsupport/knowledge-center/user-data-replace-key-pair-ec2/ > > What is the syntax of cloud configs? The most unclear thing is once. > Once per what? Is it documented? If I don't specify the > cloud_final_modules key, does it change anything? > > Regards, > Yuri > > -- > Mailing list: https://launchpad.net/~cloud-init > Post to : [email protected] > Unsubscribe : https://launchpad.net/~cloud-init > More help : https://help.launchpad.net/ListHelp -- Mailing list: https://launchpad.net/~cloud-init Post to : [email protected] Unsubscribe : https://launchpad.net/~cloud-init More help : https://help.launchpad.net/ListHelp
