[cs615asa] HW6

[Jan Schaumann]

Andrew J Neurohr <aneurohr at stevens.edu> wrote:
 
> The manpage says that ec2-backup doesn't create any temporary files.
> Does this apply to the key file we may have to create if the user does
> not specify the key-name in EC2_BACKUP_FLAGS_AWS? If so, should the
> program fail if the user does not provide this information?

Your program should not check the environment variable for what it may
contain.  It is up to the user to set it, if they need.  A user may also
have their ~/.ssh/config set up such that nothing needs to be done to
have ssh use a specific ssh key.

Your program can thus invoke e.g. 'aws ec2 ${EC2_BACKUP_FLAGS_AWS}' or
'ssh ${EC2_BACKUP_FLAGS_SSH}' without specifying any other flags that
would be specific to a user's credentials or keys.

> Also, if the user does not provide a security group, should we assume
> that the default group has proper permissions for SSH (and fail
> otherwise), or should we create a security group if none is given?

Either one is fine.  Either way, you need to handle ssh failures (for
whatever reason) gracefully.

-Jan