[ET Trac] [Einstein Toolkit] #545: Use ssh ProxyCommand instead of multiple ssh commands

[Einstein Toolkit]

#545: Use ssh ProxyCommand instead of multiple ssh commands
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  Reporter:  eschnett     |       Owner:  eschnett
      Type:  enhancement  |      Status:  review  
  Priority:  major        |   Milestone:          
 Component:  SimFactory   |     Version:          
Resolution:               |    Keywords:          
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Comment (by eschnett):

 The quote handling in this patch is off. Simfactory has a function
 QuoteSafe that quotes its argument, so that it can safely be passed to
 other commands such as bash or ssh. Instead of removing quotes or adding
 "" around a string, QuoteSafe should be used.

 The current trampoline code is written recursively and can handle multiple
 levels of trampolines. I am not aware of a current machine that requires
 this, but it was necessary for the SiCortex test machine. If we wanted
 e.g. to access LONI compute nodes we would still need this. The patch
 seems to remove the recursion and will thus handle only a single level of
 trampolines. This may be fine, but there then needs to be a check to
 ensure that the trampoline does not require a trampoline. Can the
 ProxyCommand mechanism be nested? Do we want this functionality? It would
 be elegant, but does complicate things.

 The current code is a bit convoluted, because the trampoline handling code
 is called both for ssh and for rsync commands. You implement this via an
 explicit switch (test if the argument is RSYNC); this may be a good idea,
 but an additional boolean argument may be a cleaner approach. Also, the
 current patch doesn't make it clear under which circumstances cmd would be
 empty or non-empty. I guess this is for "login" and "execute",
 respectively?

 The nc command should be quoted with QuoteSafe instead of an explicit
 backslash.

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Ticket URL: <https://trac.einsteintoolkit.org/ticket/545#comment:2>
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