core:bindtolocalhostratherthanallinterfaces

Summary:
Prior to this change, TensorBoard would default to serving on the entire
local network; now, TensorBoard serves to the local machine only, and
the flag

can be used to dual-bind to IPv4 and IPv6 on the
entire local network (the previous default). See #2387 and comments
therein for details.

Test Plan:
On my Debian machine, running with

:

• running with no
  

  1

  --host

  flag:

  • can connect to loopback on IPv4 only
  
  
  • cannot connect over LAN
  
  
  • 
    

    1

    strace

    shows binding on

    1

    AF_INET

    
    
  
  
  • a notice about
    

    1	--bind_all

    is printed to stderr

  
  


• running with
  

  1	--host&＃061;localhost

  :

  • same behavior as with no
    

    1

    --host

    flag, but no notice is printed

  
  


• running with
  

  1	--host&＃061;&＃039;::1&＃039;

  :

  • can connect to loopback on IPv6 only
  
  
  • cannot connect over LAN
  
  
  • 
    

    1

    strace

    shows binding on

    1

    AF_INET6

    
    
  
  


• running with
  

  1	--host&＃061;0.0.0.0

  :

  • can connect to loopback on IPv4 only
  
  
  • can connect over LAN
  
  
  • 
    

    1

    strace

    shows binding on

    1

    AF_INET

    
    
  
  


• running with
  

  1	--host&＃061;&＃039;::0&＃039;

  :

  • can connect on both IPv4 and IPv6
  
  
  • can connect over LAN
  
  
  • 
    

    1

    strace

    shows binding on

    1

    AF_INET6

    
    
  
  


• running with
  

  1	--bind_all

  :

  • can connect on both IPv4 and IPv6
  
  
  • can connect over LAN
  
  
  • 
    

    1

    strace

    shows binding on

    1

    AF_INET6

    with an additional syscall
    to

    1	setsockopt(3, SOL_IPV6, IPV6_V6ONLY, [0], 4)

    to facilitate
    the dual-binding, which is not present in any other tested case

  
  

In all cases, the printed serving URL (“TensorBoard x.y.z running at…”)
bears the exact

flag, or my full hostname if

was
given, or

if neither was given. In all cases, the URL is a
clickable link in my

.

Note that on my system dual binding to

works without an explicit
syscall—i.e.,

defaults to

—but this is not portable.

Connection testing was performed via

in all cases.

wchargin-branch: localhost-only

该提问来源于开源项目：tensorflow/tensorboard