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NetOps Coding 201auto remediation for your network!
NANOG 66
02.10.2016
david swafford
continuing our theme
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automating
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the remediation of network faults
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based on parsing of syslog messages
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focusing today
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on building the system
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goals• organized to support 100s of
remediations
• fast enough to react to 100s of events at at time
• simple enough to manage without a CS background
how it works
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device B
device A
Ethernet
Ethernet
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device
device link down!X device B
device A
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syslog server
sendsmessage
1
device
device X
%ETHPORT-5-IF_DOWN_LINK_FAILURE:InterfaceEthernet5/1isdown(Linkfailure)
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syslog server
sendsmessage
parser
tails messages
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2
device
device X
%ETHPORT-5-IF_DOWN_LINK_FAILURE:InterfaceEthernet5/1isdown(Linkfailure)
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syslog server
sendsmessage
parser
tails messages
1
2
device
device X
regex convertsmessage into data
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syslog server
sendsmessage
parser dbcreates
event
tails messages
1
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device
device X
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syslog server
sendsmessage
parser dbcreates
event
event processor
gets
event
tails messages
1
23 4
device
device X
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syslog server
sendsmessage
parser dbcreates
event
event processor
gets
event
tails messages
1
23 4
remediation
runs5
device
device X
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syslog server
sendsmessage
parser dbcreates
event
event processor
gets
event
tails messages
1
23 4
remediation
runs5
remediates6device
device X
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syslog server
sendsmessage
parser dbcreates
event
event processor
gets
event
tails messages
1
23 4
remediation
runs5
remediates6
saves result
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device
device X
remediates
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syslog server
sendsmessage
parsercreates
event
tails messages
1
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6device
device Xtoday's focus
dbevent
processorgets
event
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remediation
runs5
saves result
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demo!
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syslog generator
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syslog generator
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syslog generator
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syslog generator
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syslog parser
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syslog parser
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syslog parser
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event processor
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event processor
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event processor
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event processor
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event processor
the lab environment
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a virtual machine of Ubuntu desktop
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customized with
iPython! and extras
Python 2.7.11 & 3.5.1 MySQL server & Python libs
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importing the virtual appliance
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TERMINAL
log-in details
user:demopass:demo
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keyboard shortcuts to break out of the VM
f enter or leave full-screen
getting started
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organizing our data
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the event as a tuple
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the event as a tuple
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what's the problem?
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what's the problem?new field!
data formats will change
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the event as a dictionary
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the event as an object
link
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accessing attributes of an object
link
which to choose?
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the advantage of an object
enforcement of structure
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the advantage of an object
input validation (not shown)
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where to find it?
:Event()
• a database (MySQL)
• an events table
• a library for managing our data
• installation of "netfbar"(a Python package)
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what's already staged?
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database setup
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netfbar package
the parser
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where to find it?
remediations, refactored.
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a few problems
• duplication
• no structure
• limited debug-ability
organizing our remediations
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"sparse is better than dense"
1 remediation, 1 file.
...remediations, v2.
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code that repeats in each remediation
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moved to a base remediation
remediations, v2.
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from base.BaseRemediation
remediations, v2.
connecting remediations to error codes
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71a dictionary of "error_code" to "module"
connecting remediations to error codes
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connecting remediations to error codes
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where to find it?
questions?
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building the event processor
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starting simple
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building it live
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building it live
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building it live
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building it live
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building it live
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no events?
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building it live
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building it live
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building it live
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building it live
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building it live
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building it live
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building it live
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building it live
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building it live
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building it live
(no logging in the default remediation)
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building it live
create a function for handling one event
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building it live
iterating through events
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building it live
so slow!
questions?
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making this a little faster
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• threading • multiprocessing • asyncio • gevent • go...
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so many choices!
starting simple!
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threading & multiprocessing
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threading's pros
https://docs.python.org/3/library/threading.html
• simple API
• lightweight
• shared memory with the parent
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threading's cons
https://docs.python.org/3/library/threading.html
• not true parallelism
• all threads are limited to a single CPU - the parent's
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threads are evil! ....?!
https://docs.python.org/3/library/threading.html
"In CPython, due to the [GIL], only one thread can execute Python code at once"
...
"However, threading is still an appropriate model if you want to run multiple
I/O-bound tasks simultaneously."
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multiprocessing's pros
https://docs.python.org/3/library/threading.html
• simple API
• true parallelism using all CPUs
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multiprocessing's cons
https://docs.python.org/3/library/threading.html
• based on forking (cloning/copying the current process)
• heavier memory footprint
• stale memory / state
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multiprocessing's cons
https://docs.python.org/3/library/threading.html
• no shared memory with parent
working with threads
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working with threads
https://docs.python.org/3/library/threading.html
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working with threads
https://docs.python.org/3/library/threading.html
target - the method to run inside the thread
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working with threads
https://docs.python.org/3/library/threading.html
args - the values passed as input to process_event()
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working with threads
https://docs.python.org/3/library/threading.html
.start() - spins up the thread in the background (the for loop continues)
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working with threads
https://docs.python.org/3/library/threading.html
caution! this is dangerous! (starting an unknown number of threads)
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adding visibility to process_event()
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starting our threads again (with visibility)
https://docs.python.org/3/library/threading.html
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starting our threads again (with visibility)
https://docs.python.org/3/library/threading.html
oh my! ...that just started 1020 threads!
creating a thread pool
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creating a thread pool
the work to perform inside a thread
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creating a thread pool
starting the background threads
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creating a thread pool
looking at active threads
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creating a thread pool
looking at active threads
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creating a thread pool
fetching events that we'll send to the threads
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creating a thread pool
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creating a thread pool
https://docs.python.org/3/library/threading.html
creating a queue to pass events to threads
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creating a thread pool
putting the pieces together
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creating a thread pool
putting the pieces together
...
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creating a thread pool
now, continuously!
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creating a thread pool
questions?
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closing out
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syslog server
sendsmessage
parser dbcreates
event
event processor
gets
event
tails messages
1
23 4
remediation
runs5
remediates6
saves result
7
device
device X
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goals• organized to support 100s of
remediations
• fast enough to react to 100s of events at at time
• simple enough to manage without a CS background
NANOG 66
02.10.2016
david swafford
#netengcode
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