Security
.env.vault
The .env.vault file uniquely identifies your project in dotenv-vault. You SHOULD commit this file to source control. It is safe to do so. Aside: DON'T commit your .env or .env.me to source control.
You can think of it like a unique git url at GitHub. It identifies your project so that your teammates pull the correct .env file from dotenv-vault.
Example
Here's an example of what a .env.vault file looks like:
DOTENV_VAULT=vlt_9a165d…
The first thing you might notice is the formatting is the same as a .env file. This is intentional to allow for maximum future interoperability.
The DOTENV_VAULT key is important. It is required. It is that value that identifies your project uniquely to the dotenv vaulting mechanisms.
Generating
You can generate a .env.vault file at vault.dotenv.org or through dotenv-vault. The process is similar to creating and cloning your very first git repo on GitHub.