At the moment, the "sign_addons" management command expects a list of addon ids to sign. There's no way to make it sign all the addons at once. It also doesn't filter out the files/versions that are already signed.
Instead of modifying the `sign_addons` management command to be able to sign all addons, I've added a task to be used with `process_addons --task sign_addons`. Fixed in https://github.com/mozilla/olympia/commit/ead4d7b1ed30241138bf6a2ace54763f68d2fd66
/me thinks we should be writing documentation for these commands as we do them. If there isn't a good spot in the actual docs, maybe just adding a section to the wiki would be good enough. What do you think?
Following your advice, I've added a small note to the wiki: https://wiki.mozilla.org/AMO/SigningService#Usage