`butane` command is incorrect and needs an additional command line option added to it to function properly.

tested with butane version Butane 0.21.0    

always

    1. run the command shown in step 3b under "Configuring IPsec encryption for external traffic"     
    2. you will get an error `error at $.storage.files.0.contents.local, line 30 col 16: local file paths are relative to a files directory that must be specified with -d/--files-dir
Error translating config: source config is invalid`
    

yaml files are not created and you get an error:

"error at $.storage.files.0.contents.local, line 30 col 16: local file paths are relative to a files directory that must be specified with -d/--files-dir"

yaml files are created correctly

Steps to fix error are below (add "-d ." to command to pull from current directory) 

$ for role in master worker; do   
  butane -d . 99-ipsec-${role}-endpoint-config.bu -o ./99-ipsec-$role-endpoint-config.yaml; 
done