supervacuo.com

duplicity has built-in support for Backblaze B2, but the documentation in man duplicity on how to use it is, um, brief:

b2://account_id[:application_key]@bucket_name/[folder/]

(the word "Backblaze" doesn't even appear in the man-page..)

To demystify slightly:

• account_id is either the keyID of the "Master Application Key" under "App keys", or the keyID of an application key you have created (on that same page)
• application_key has to be provided unless you want duplicity to prompt for it on each run. It is the applicationKey field, again either for the "Master Application Key" or for an application key. In either case, you can only see the applicationKey after creating (or re-creating) the key
• bucket_name is the plain-text name of your bucket, not the "Bucket ID" string

Happy backing-up.