Per http://docs.ansible.com/ansible/playbooks_vault.html you can set an environment variable to use a password file for vault access. We can use this to create an environment variable to hold the password.
Copy vault-env from this project to ~/bin. Then add this to your ~/.bashrc:
export ANSIBLE_VAULT_PASSWORD_FILE=~/bin/vault-envNow just export your password in your shell as needed. Don't be a douche and put this in your profile though.
export ANSIBLE_VAULT_PASSWORD=<password>
Contrary to the comment above, this does still work. And while using a custom env var is nice, the real power lies in using the script to fetch the vaultpass directly from OpenBao, Hashicorp Vault, or your password manager.