Fabric python not generating full output and aborting in middle

Question

I am trying fabric to fetch few inputs from cisco Nexus switch and output displaying disconnecting with error

error:

  c:\Python27>Scripts\fab.exe -f D:\Python-scripts\nexus-fabric.py sh  -H     10.10.10.10 -u admin
  [10.10.10.10] Executing task 'sh'
  [10.10.10.10] run: terminal length 0
  [10.10.10.10] Login password for 'admin':
  [10.10.10.10] out: gl_set_term_size: NULL arguments(s).
  [10.10.10.10] out:

  [10.10.10.10] run: show interface brief
  [10.10.10.10] out:
  [10.10.10.10] out: -------------------------------------------------------   ------------------------
  [10.10.10.10] out: Interface  Vsan   Admin  Admin   Status          SFP         Oper  Oper   Port
  [10.10.10.10] out:                   Mode   Trunk                            Mode  Speed  Channel
  [10.10.10.10] out:                          Mode                                 (Gbps)
 [10.10.10.10] out: -------------------------------------------------------------------------------
 [10.10.10.10] out: fc2/1      4094   auto   on      sfpAbsent        --     --           --
 [10.10.10.10] out:


 Fatal error: run() received nonzero return code -1 while executing!

 Requested: show interface brief
 Executed: show interface brief

 Aborting.
 Disconnecting from 10.10.10.10... done.

code:

  from fabric.api import run
  def sh():
     run("terminal length 0",shell=False)
     run("show interface brief",shell=False

I used Pass option still it is failing:

from fabric.api import run
from fabric.api import settings
from fabric.api import warn_only
def sh():
    try:
       run("show running-config",shell=False)
       run("show interface brief",shell=False)
    except:
       pass

If we run one command i used get output without issues but if i use two run commands second command is terminating with below error

Fatal error: run() received nonzero return code -1 while executing!

I have tried exception as suggested but i am getting below is code and error:

from fabric.api        import env,run
from fabric.operations import sudo

class FabricException(Exception):
   pass

env.abort_exception = FabricException
# ... set up the rest of the environment...

def sh():
    try:
       run("show interface brief",shell=False)
       run("show running-config",shell=False)
    except FabricException:
        pass  # This is expected, we can continue.

If Please help

Fabric version :

     c:\Python27>Scripts\fab.exe --version
     Fabric 1.13.1
     Paramiko 2.1.2

Python 2.7

please help

Answer 1

Updated answer:

As Cisco routers are not plain unix, Fabric won't work reliably on such systems. See this github issue for further details.

Old answer:

Fabric runs in fast-fail behavior as default, that is both stated in doc and this answer. I see your command is not critical and you use it mostly for inspection purposes, then you might ignore the exit code by wrapping it as follows:

with settings(warn_only=True):
    run("show interface brief",shell=False)

That will skip the line even command ends with non-zero return. Finally, you would need following import statement to make with block work:

from fabric.api import settings

Update

To completely ignore any failure during the command without using any settings wrapper:

try:
    run("show interface brief",shell=False)
except:
    pass

Update 2 (with exception class)

Taken from this answer:

from fabric.api        import env
from fabric.operations import sudo

class FabricException(Exception):
    pass

env.abort_exception = FabricException
# ... set up the rest of the environment...

def sh():
    try:
        run("show interface brief",shell=False)
    except FabricException:
        pass  # This is expected, we can continue.