netmiko connections from device list is only connecting to first ip in list - netmiko

Question

Im using
(base) C:\python
Python 3.8.8 (default, Apr 13 2021, 15:08:03) [MSC v.1916 64 bit (AMD64)] :: Anaconda, Inc. on win32
Type "help", "copyright", "credits" or "license" for more information.sing
Created on Wed Jun 16 10:15:59 2021
import logging
from netmiko import ConnectHandler
logging.basicConfig(filename='test2.log', level=logging.DEBUG)
logger = logging.getLogger("netmiko")
with open('host.txt', "r") as host:
for ip in host.read().splitlines():
cisco = {
'device_type': 'cisco_ios',
'ip': ip,
'username': 'user',
'password': 'password',
}
net_connect = ConnectHandler(**cisco)
print (' #### Connecting to ' + ip)
output = net_connect.find_prompt()
print(output)
net_connect.disconnect()

Answer 1

You need to create a for loop. Netmiko accepts one dictionary within the ConnectHandler class. So to make the code run "for each" device, you have to create a loop.
Also, in the for loop you created to read the IP addresses from hosts.txt, you keep overwriting the cisco dict every time in the loop. cisco = {} overwrites the previous value each time. New values should be appended to a list instead.
You can achieve this by doing:
from netmiko import ConnectHandler
import logging
logging.basicConfig(filename="test2.log", level=logging.DEBUG)
logger = logging.getLogger("netmiko")
with open(file="hosts.txt", mode="r") as hosts:
# A list comprehension
devices = [
{
"device_type": "cisco_ios",
"ip": ip,
"username": "cisco",
"password": "cisco",
}
for ip in hosts.read().splitlines()
]
print(devices) # <--- print value is below
# Connect to each device (one at a time)
for device in devices:
print(f'Connecting to {device["ip"]}') # Here you are still trying to connect
net_connect = ConnectHandler(**device)
print(f'Connected to {device["ip"]}') # Here you are already connected
prompt = net_connect.find_prompt()
net_connect.disconnect() # disconnect from the session
# Finally, print the prompt within the foor loop, but
# after you disconnect. You no longer need the connection to print.
print(prompt)
You can forget about net_connect.disconnect() by using with statement (Context Manager)
It's important to clear the vty line after you are done
for device in devices:
print(f'Connecting to {device["ip"]}') # Here you are still waiting to connect
with ConnectHandler(**device) as net_connect:
print(f'Connected to {device["ip"]}') # Here you are already logged-in
prompt = net_connect.find_prompt()
print(prompt)
If you print the devices list, you will get:
[{'device_type': 'cisco_ios',
'ip': '192.168.1.1', # From hosts.txt file
'password': 'cisco',
'username': 'cisco'},
{'device_type': 'cisco_ios',
'ip': '192.168.1.2', # From hosts.txt file
'password': 'cisco',
'username': 'cisco'}]