We are using a .env file for storing the key for mailersend gem because it requires a .env file. And fly.io does not support fetching variables from the .env file. When I try to deploy the code it gives an error for mailersend variable.
I use the ‘[env]’ in the fly.toml for setting that are not secret.
And then I use ‘fly secrets set MY_VAR=theValueOfVar’ for secrets, which are passwords, keys, webhook endpoints that should be masked, personal contact data (like admin email).