いったんは、ask-vault-passと、createをおぼえるといいと思いました。
ansible-vault --help
Usage: ansible-vault [create|decrypt|edit|encrypt|rekey|view] [--help] [options] vaultfile.yml
Options:
--ask-vault-pass ask for vault password
-h, --help show this help message and exit
--new-vault-password-file=NEW_VAULT_PASSWORD_FILE
new vault password file for rekey
--output=OUTPUT_FILE output file name for encrypt or decrypt; use - for
stdout
--vault-password-file=VAULT_PASSWORD_FILE
vault password file
-v, --verbose verbose mode (-vvv for more, -vvvv to enable
connection debugging)
--version show program's version number and exit