In general, bind to 0.0.0.0 and not private_ip; separate notion of :addr and :bindto

[mrflip]

Whatever the merits of binding to a single interface, the following compelling arguments say "no, just have everything bind to 0.0.0.0 (i.e. serve on all available interfaces)":

• probing localhost (curl, mongostat, etc) is easier from the commandline than probing hostname -f.
• it leads to messy logic in the cookbooks
• lockdown to single interfaces can be done at the firewall level. It's reasonable to say this is a concern of a firewall, and thus should be handled by a firewall-rule amenity to be written later.

So, we should:

• Remove logic in cookbooks that binds to private ip's
  • Be very careful of things like hadoop's fs.default.name -- make sure that the config variable is a bind statement and not an publishment-of-capability statement.
• Separate the following node attributes:
  • :addr -- "where to find me". Defaults to nil, set at runtime, has the appropriate hostname of the machine, set by the announce helper.
  • :bindto -- "the interface I should attach to". Defaults to 0.0.0.0 and left there. Right now this attribute is spelled 'addr' in most places
• have the announce helper set the addr attribute (accepting an override) -- this is the "address to use for this capability"