https://www.arista.com/assets/data/pdf/Whitepapers/Arista_EOS_parser.pdf
Arista EOS CLI is implemented in Python, so you can customize the CLI yourself. Of course it is limited to simple output instead of complicated contents.
Step 1: Modify the CLI script
bn303.17:40:17#bash
Arista Networks EOS shell
[admin@bn303 ~]$ cd /usr/lib/python2.7/site-packages/CliPlugin/
[admin@bn303 CliPlugin]$ vi RoutingBgpShowCli.py
[admin@bn303 CliPlugin]$ sudo vi RoutingBgpCli.py
Step 2: save the new CLI script and load up during boot
copy the modified to /mnt/flash
the /usr/lib is file system in memory, unsustainable after reboot.
vi /mnt/flash/rc.eos, so copy the save script to the location
Showing posts with label python. Show all posts
Showing posts with label python. Show all posts
12/02/2018
11/29/2018
Python Notes (3) - Beautiful Python Code by Raymond Hettinger
https://www.youtube.com/watch?v=OSGv2VnC0go
Faster and prettier code:
1. Looping backwards
for color in reversed(colors):
print color
2. Looping over collection and indices
for i, color in enumerate(colors):
print i, ":", color
3. Zip of 2 lists
for name, color in zip(names, colors):
print name, ":", color
! zip has higher memory req, prone to cache miss;
! in python 3.x, using izip instead of zip
4. Sorted list
for color in sorted(colors):
for color in sorted(colors, reverse=True):
def compare_length(c1, c2):
if len(c1) < len(c2): return -1
if len(c1) > len(c2): return 1
return 0
for color in sorted(colors, cmp=compare_length):
for color in sorted(colors, key=len):
Looping over a dict with keys and values:
for k,v in d.items(): # req. memory to store list
for k,v in d.iteritems(): # use iterator instead of mem
Counting with dict
d ={}
for color in colors:
d[color] = d.get(color, 0) + 1
d = defaultdict(int)
for color in colors:
d[color] += 1
Grouping with dictionaries:
# group the list by length
names = ['Raymond', 'Rachel', 'Matthew', 'Roger', 'Betty']
#old
d = {}
for name in names:
key = len(name)
if key not in d:
d[key] = []
d[key].append(name)
#1
d = {}
for name in names:
key = len(name)
d.setdefault(key, []).append(name)
#2
d = defaultdict(list)
for name in names:
key = len(name)
d[key].append(name)
Function calls with keyword arguments
twitter_search('@obama', False, 20, True)
twitter_search('@obama', retweets=False, numtweets=20,
popular=True)
Faster and prettier code:
1. Looping backwards
for color in reversed(colors):
print color
2. Looping over collection and indices
for i, color in enumerate(colors):
print i, ":", color
3. Zip of 2 lists
for name, color in zip(names, colors):
print name, ":", color
! zip has higher memory req, prone to cache miss;
! in python 3.x, using izip instead of zip
4. Sorted list
for color in sorted(colors):
for color in sorted(colors, reverse=True):
def compare_length(c1, c2):
if len(c1) < len(c2): return -1
if len(c1) > len(c2): return 1
return 0
for color in sorted(colors, cmp=compare_length):
for color in sorted(colors, key=len):
Looping over a dict with keys and values:
for k,v in d.items(): # req. memory to store list
for k,v in d.iteritems(): # use iterator instead of mem
Counting with dict
d ={}
for color in colors:
d[color] = d.get(color, 0) + 1
d = defaultdict(int)
for color in colors:
d[color] += 1
# group the list by length
names = ['Raymond', 'Rachel', 'Matthew', 'Roger', 'Betty']
#old
d = {}
for name in names:
key = len(name)
if key not in d:
d[key] = []
d[key].append(name)
#1
d = {}
for name in names:
key = len(name)
d.setdefault(key, []).append(name)
#2
d = defaultdict(list)
for name in names:
key = len(name)
d[key].append(name)
Function calls with keyword arguments
twitter_search('@obama', False, 20, True)
twitter_search('@obama', retweets=False, numtweets=20,
popular=True)
Packing/Unpacking = simultaneous state updates
x, y, dx, dy = ( x + dx *t,
y + dy *t,
influence(m,x,y),
influence(m,x,y))
Concatenating strings
', '.join(names)
Updating sequences
names = ['Raymond', 'Rachel', 'Matthew', 'Roger', 'Betty']
del names[0]
names.pop(0)
names.insert(0, 'mark')
#==>
names = deque(['Raymond', 'Rachel', 'Matthew', 'Roger', 'Betty'])
del names[0]
names.popleft()
names.appendleft('mark')
Python Notes (2)
1. Sort:
>>> p.sort(key=lambda x:(x[0], x[2]))
>>> p
[[1, 7, 2], [1, 2, 3], [1, 2, 5], [1, 3, 7], [2, 4, 6], [3, 1, 0], [3, 2, 1]]
>>> p.sort(key=lambda x:(-x[0], x[2]))
>>> p
[[13, 1, 0], [3, 2, 1], [2, 4, 6], [1, 2, 3], [1, 2, 5], [1, 3, 7], [-1, 7, 2]]
1) No duplicate
2) No order
3) Sets contain only hashable items, for __contain__ method
4) Sets have operator like "-"
_set = set([1,2,3,3]) # (1,2,3)
l1 = [1,2,3,4]
- sorted() vs list.sort()
- Sorted() returns a new list vs list.sort() does in place.
- list.sort() only for list. But sorted() for all iterables.
- key function and (reverse=True)
- Sorted by multiple elements, like by first item then 2nd.
>>> p.sort(key=lambda x:(x[0], x[2]))
>>> p
[[1, 7, 2], [1, 2, 3], [1, 2, 5], [1, 3, 7], [2, 4, 6], [3, 1, 0], [3, 2, 1]]
- Sorted by reversed plus asc
>>> p.sort(key=lambda x:(-x[0], x[2]))
>>> p
[[13, 1, 0], [3, 2, 1], [2, 4, 6], [1, 2, 3], [1, 2, 5], [1, 3, 7], [-1, 7, 2]]
2. SET:
1) No duplicate
2) No order
3) Sets contain only hashable items, for __contain__ method
4) Sets have operator like "-"
_set = set([1,2,3,3]) # (1,2,3)
s1 = set([1,2,3,4])
s2 = set([2,3,5])
l1 = [1,2,3,4]
l2 = [2,3,5]
s1 - s2
set([1, 4])
l1 - l2
Error
3. Variable length arguments in function call
positional argument with unknown number of arguments
def __func__(*args):
for count, item in enumerate(args):
print '{0}. {1}'.format(count, thing)
named arguments
def __func__(**kwargs):
for name, value in kwargs.items():
print '{0} = {1}' % (name, value)
TCL:
proc __proc__ {first args} {}
4. How to re-import python module in interactive mode
>>> from myrange import *
>>> for i in myrange(1,3,1):
... print i
...
1 <<<<< extra print out due to debug print
1
2
$ more myrange.py
class myrange:
def __init__(self, start, end, step):
self.start = start
self.end = end
self.step = step
print self.step <<<< need to remove this
5. Python class class/instance/internal variables
啥叫class/instance/internal variables?
- classVar 是Object之间share，一个改，大家都改，也叫Static variable
- instanceVar，所以叫Self.instanceVar，就是object自己本地
- internal，就不说了
class Obj(object):
classVar = [10,20,30]
def __init__(self):
self.instanceVar = [1,2,3]
internalVar = [100,200,300]
o1 = Obj()
o2 = Obj()
o1.instanceVar.append(11)
o1.instanceVar.append(12)
o2.instanceVar.append(21)
o2.instanceVar.append(22)
print o1.instanceVar
print o2.instanceVar
o1.classVar.append(111)
o2.classVar.append(222)
print o1.classVar
print o2.classVar
3. Variable length arguments in function call
positional argument with unknown number of arguments
def __func__(*args):
for count, item in enumerate(args):
print '{0}. {1}'.format(count, thing)
named arguments
def __func__(**kwargs):
for name, value in kwargs.items():
print '{0} = {1}' % (name, value)
TCL:
proc __proc__ {first args} {}
4. How to re-import python module in interactive mode
>>> from myrange import *
>>> for i in myrange(1,3,1):
... print i
...
1 <<<<< extra print out due to debug print
1
2
class myrange:
def __init__(self, start, end, step):
self.start = start
self.end = end
self.step = step
print self.step <<<< need to remove this
Change the py file, and do 2 steps
>>> import myrange <<< need to import module for reload()
>>> reload(myrange)
<module 'myrange' from 'myrange.py'>
>>> from myrange import *
>>> for i in myrange(1,3,1):
... print i
...
1 <<<< corrected
2
啥叫class/instance/internal variables?
- classVar 是Object之间share，一个改，大家都改，也叫Static variable
- instanceVar，所以叫Self.instanceVar，就是object自己本地
- internal，就不说了
class Obj(object):
classVar = [10,20,30]
def __init__(self):
self.instanceVar = [1,2,3]
internalVar = [100,200,300]
o1 = Obj()
o2 = Obj()
o1.instanceVar.append(11)
o1.instanceVar.append(12)
o2.instanceVar.append(21)
o2.instanceVar.append(22)
print o1.instanceVar
print o2.instanceVar
o1.classVar.append(111)
o2.classVar.append(222)
print o1.classVar
print o2.classVar
Python Notes (1)
1. Python FAQ:
https://docs.python.org/2.7/faq/programming.html
2. Python module search path
https://docs.python.org/2.7/tutorial/modules.html#the-module-search-path
If you do an "import syslib", how does the python locate the library?
1. local directory <<<< surprised?!
2. PYTHONPATH
so if you have a locally mistaken syslib.py or syslib.pyc under the local directory, you gonna break this import. And if you see something wanky, print cmd.__file__ will be helpful (or cmd.__version__)
3. Python Set
https://docs.python.org/3/tutorial/datastructures.html#sets
https://docs.python.org/2.7/faq/programming.html
2. Python module search path
https://docs.python.org/2.7/tutorial/modules.html#the-module-search-path
If you do an "import syslib", how does the python locate the library?
1. local directory <<<< surprised?!
2. PYTHONPATH
so if you have a locally mistaken syslib.py or syslib.pyc under the local directory, you gonna break this import. And if you see something wanky, print cmd.__file__ will be helpful (or cmd.__version__)
3. Python Set
https://docs.python.org/3/tutorial/datastructures.html#sets
- {} and set() can be used to create set
- But to create an empty one, must use set(), not {} which is to create a dictionary.
- set_ = {0}
4. 3 Ways to delete an element in a list
1) most efficient - del List[idx]
2) less efficient if need to have the element - List.pop(idx)
3) lest effificient - slice, List[:i] + List[i+1:]
5. Python reduce, filter
>>> l = [1,2,3,4]
>>> reduce( (lambda x,y: x*10+y), l)
1234
>>> reduce( (lambda x,y: x*100+y), l)
1020304
>>> l = range(1, 100, 5)
>>> l
[1, 6, 11, 16, 21, 26, 31, 36, 41, 46, 51, 56, 61, 66, 71, 76, 81, 86, 91, 96]
>>> filter(lambda x:x%4, l)
[1, 6, 11, 21, 26, 31, 41, 46, 51, 61, 66, 71, 81, 86, 91]
6. Python Naming Convention
http://legacy.python.org/dev/peps/pep-0008/#code-lay-out
2) less efficient if need to have the element - List.pop(idx)
3) lest effificient - slice, List[:i] + List[i+1:]
5. Python reduce, filter
>>> l = [1,2,3,4]
>>> reduce( (lambda x,y: x*10+y), l)
1234
>>> reduce( (lambda x,y: x*100+y), l)
1020304
>>> l = range(1, 100, 5)
>>> l
[1, 6, 11, 16, 21, 26, 31, 36, 41, 46, 51, 56, 61, 66, 71, 76, 81, 86, 91, 96]
>>> filter(lambda x:x%4, l)
[1, 6, 11, 21, 26, 31, 41, 46, 51, 61, 66, 71, 81, 86, 91]
6. Python Naming Convention
http://legacy.python.org/dev/peps/pep-0008/#code-lay-out
- limit all lines to 79，docstring/comment to 72
class Rectangle(Blob):
def __init__(self, width, height,
color='black', emphasis=None, highlight=0):
if (width == 0 and height == 0 and
color == 'red' and emphasis == 'strong' or
highlight > 100):
raise ValueError("sorry, you lose")
if width == 0 and height == 0 and (color == 'red' or
emphasis is None):
raise ValueError("I don't think so -- values are %s, %s" %
(width, height))
Blob.__init__(self, width, height,
color, emphasis, highlight)
- Module: short,
- all-lower-case name, like pystock.py
- Class: CapWords, like
- StockHist, StockInfo, StockERHist
- Function:
- lower_case_with_underscore
- Method and instance:
- lower_case_with_underscore
- Constants:
- ALL_CAPITALS_WITH_UNDERSCORE
- Internal attribute:
- _single_leading_underscore
- NOT imported.
- empty sequence = FALSE, so
- YES: if not seq:...
- NO: if len(seq)
- Attributes:
- self.lower_case_with_underscore
9/12/2018
Python Tips
1. Is vs ==, mutable and immutable
>>> id(a)
4463753048 <<<< address is 048
>>> a[0] = 11
>>> id(a)
4463753048
>>> a
[11, 2, 3]
>>> a.append(44)
>>> a
[11, 2, 3, 44]
>>> id(a) <<<< can change item and append, address is same
4463753048
>>> b = a
>>> id(b) <<<< list= is point to same address
4463753048
>>> b[0] = 111
>>> a
[111, 2, 3, 44] <<<< change b = change a
>>> c = a[:]
>>> id(c)
4463919328
>>> c[0] = 1234
>>> a
[111, 2, 3, 44]
>>> b
[111, 2, 3, 44]
>>> c
[1234, 2, 3, 44]
>>>
2. keyword argument
>>> def ff(*args, **kwargs):
... print args
... print kwargs
...
>>> ff(1, '22', k1=333, k2='4444')
(1, '22')
{'k2': '4444', 'k1': 333}
>>> d = {'ka':'aaa', 'kb':123}
>>> ff(**d)
()
{'kb': 123, 'ka': 'aaa'}
3. Regexp \符号
https://docs.python.org/3/howto/regex.html
Remove全部的None-Alphanumeric char from string. 应该是
s = re.sub('\W', '', s)
还有记住以下的
\d, \D = [0-9]
\s, \S = [ \t\n\r\v\f]
\w, \W = alphanumeric,[0-9a-bA-Z_]
4. arstCli Script模版
from arstCliLib import *
import sys
dut = sys.argv[1]
openSshOnDut( dut )
setAccessMethod(dut, 'ssh')
cmd = ['show ip int brief | grep " 10\." | grep Vlan']
output = sendCmd(dut, cmd, prompt='enable', raw=True)
print '\n'.join(output)
[solomonyang@syscon] ~ $ python testCli.py
Traceback (most recent call last):
File "testCli.py", line 4, in <module>
from arstCliLib import *
ImportError: No module named arstCliLib
PATH=$PATH:$HOME/bin:$HOME/py
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$HOME/git/systest-infra/lib/
PYTHONPATH=$PYTHONPATH:$HOME/git/systest-infra/lib/
export PATH
export LD_LIBRARY_PATH
export PYTHONPATH
5. List vs Tuple, based on stackoverflow post
2
1
800024
900088
3. Mutable vs Inmutable/可变 vs 不可变
>>> t = (1,2); l = [1,2]
>>> l[0] = 11; print l
[11, 2]
>>> t[0] = 11; print t
TypeError: 'tuple' object does not support item assignment
4. 都可以增加，但是不同，tuple += (3)是返回一个新的obj，而list.add()是改原来的
>>> t = (1,2); l = [1,2]; id(t); id(l); t+=(3,); l+=[3]; id(t); id(l); l.append(3); id(l)
4306859000 <<<<< t
4307014720 <<<<< 1, 都一个地址
4306913952 <<<<< t +=(3,)，新地址
4307014720
4307014720
5. 因为不可变，所以tuple (1,2)可以是Dict[key]
>>> d = {}; d[t] = '1,2'
>>> d = {}; d[l] = '1,2'
TypeError: unhashable type: 'list'
6. 用途
比方说，(10,11)是个bookmark，第10页的第11行，一般没有必要改；而list of bookmark = [ (1,10), (10,11), (22, 1)]
7. Tuple != constant list
http://news.e-scribe.com/397
但是这么了解哪，好像也撮合:-) 好像更多的是字面的了解，tuple = lightweight record，比方说：DB API's fetchmany() 返回的是List of tuple. 每个tuple是一个record，不能改其中一项，改了就没有意义了。
List vs Set
1. Literal/语法/内存量
>>> s = set(range(100000)); s.__sizeof__(); l = list(range(100000)); l.__sizeof__()
4194504
900088
2. Set没有Index, 没有重复，可以数学操作 &, -, ^
>>> s1=set(range(1,20,2)); s2=set(range(10,30)); print 's1->', s1; print 's2->', s2; print '-:', s1 - s2; print '&:', s1&s2; s1^s2
s1-> set([1, 3, 5, 7, 9, 11, 13, 15, 17, 19])
s2-> set([10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29])
-: set([1, 3, 9, 5, 7])
&: set([19, 17, 11, 13, 15])
set([1, 3, 5, 7, 9, 10, 12, 14, 16, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29])
- == is to compare value, is is compare address
- == is to compare by calling object.__eq__()
- list1 = list2, address is assigned, not value. need list1=list2[:]
>>> id(a)
4463753048 <<<< address is 048
>>> a[0] = 11
>>> id(a)
4463753048
>>> a
[11, 2, 3]
>>> a.append(44)
>>> a
[11, 2, 3, 44]
>>> id(a) <<<< can change item and append, address is same
4463753048
>>> b = a
>>> id(b) <<<< list= is point to same address
4463753048
>>> b[0] = 111
>>> a
[111, 2, 3, 44] <<<< change b = change a
>>> c = a[:]
>>> id(c)
4463919328
>>> c[0] = 1234
>>> a
[111, 2, 3, 44]
>>> b
[111, 2, 3, 44]
>>> c
[1234, 2, 3, 44]
>>>
2. keyword argument
>>> def ff(*args, **kwargs):
... print args
... print kwargs
...
>>> ff(1, '22', k1=333, k2='4444')
(1, '22')
{'k2': '4444', 'k1': 333}
>>> d = {'ka':'aaa', 'kb':123}
>>> ff(**d)
()
{'kb': 123, 'ka': 'aaa'}
3. Regexp \符号
https://docs.python.org/3/howto/regex.html
Remove全部的None-Alphanumeric char from string. 应该是
s = re.sub('\W', '', s)
还有记住以下的
\d, \D = [0-9]
\s, \S = [ \t\n\r\v\f]
\w, \W = alphanumeric,[0-9a-bA-Z_]
4. arstCli Script模版
from arstCliLib import *
import sys
dut = sys.argv[1]
openSshOnDut( dut )
setAccessMethod(dut, 'ssh')
cmd = ['show ip int brief | grep " 10\." | grep Vlan']
output = sendCmd(dut, cmd, prompt='enable', raw=True)
print '\n'.join(output)
[solomonyang@syscon] ~ $ python testCli.py
Traceback (most recent call last):
File "testCli.py", line 4, in <module>
from arstCliLib import *
ImportError: No module named arstCliLib
PATH=$PATH:$HOME/bin:$HOME/py
LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$HOME/git/systest-infra/lib/
PYTHONPATH=$PYTHONPATH:$HOME/git/systest-infra/lib/
export PATH
export LD_LIBRARY_PATH
export PYTHONPATH
5. List vs Tuple, based on stackoverflow post
1. Literal/语法
>>> t = (1,2); l = [1,2]; t[1]; l[0]2
1
2. Size/内存量，区别大概list +12%
>>> t = tuple(range(100000)); l = list(range(100000)); t.__sizeof__(); l.__sizeof__()800024
900088
3. Mutable vs Inmutable/可变 vs 不可变
>>> t = (1,2); l = [1,2]
>>> l[0] = 11; print l
[11, 2]
>>> t[0] = 11; print t
TypeError: 'tuple' object does not support item assignment
4. 都可以增加，但是不同，tuple += (3)是返回一个新的obj，而list.add()是改原来的
>>> t = (1,2); l = [1,2]; id(t); id(l); t+=(3,); l+=[3]; id(t); id(l); l.append(3); id(l)
4306859000 <<<<< t
4307014720 <<<<< 1, 都一个地址
4306913952 <<<<< t +=(3,)，新地址
4307014720
4307014720
5. 因为不可变，所以tuple (1,2)可以是Dict[key]
>>> d = {}; d[t] = '1,2'
>>> d = {}; d[l] = '1,2'
TypeError: unhashable type: 'list'
6. 用途
比方说，(10,11)是个bookmark，第10页的第11行，一般没有必要改；而list of bookmark = [ (1,10), (10,11), (22, 1)]
7. Tuple != constant list
http://news.e-scribe.com/397
但是这么了解哪，好像也撮合:-) 好像更多的是字面的了解，tuple = lightweight record，比方说：DB API's fetchmany() 返回的是List of tuple. 每个tuple是一个record，不能改其中一项，改了就没有意义了。
List vs Set
1. Literal/语法/内存量
>>> s = set(range(100000)); s.__sizeof__(); l = list(range(100000)); l.__sizeof__()
4194504
900088
2. Set没有Index, 没有重复，可以数学操作 &, -, ^
>>> s1=set(range(1,20,2)); s2=set(range(10,30)); print 's1->', s1; print 's2->', s2; print '-:', s1 - s2; print '&:', s1&s2; s1^s2
s1-> set([1, 3, 5, 7, 9, 11, 13, 15, 17, 19])
s2-> set([10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29])
-: set([1, 3, 9, 5, 7])
&: set([19, 17, 11, 13, 15])
set([1, 3, 5, 7, 9, 10, 12, 14, 16, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29])
5/11/2018
How to use python/yaml
import yaml
import sys
with open(sys.argv[1], 'r') as stream:
try:
paramDict = yaml.load(stream)
except yaml.YAMLError as err:
print(err)
sys.ext(0)
print paramDict['Devices']['Switch']['mlagA']['Mgmt']['Host']
============
Devices:
Switch:
mlagA: # MLAG Dut1
Mgmt:
Host: bn303
AccessMethod: ssh # ssh or capi
SshUsername: admin # default admin
ChassisType: modular # fixed or modular
CapiProtocol: https
~/py @arst1.sjc> python test.py test.yaml
bn303
import sys
with open(sys.argv[1], 'r') as stream:
try:
paramDict = yaml.load(stream)
except yaml.YAMLError as err:
print(err)
sys.ext(0)
print paramDict['Devices']['Switch']['mlagA']['Mgmt']['Host']
============
Devices:
Switch:
mlagA: # MLAG Dut1
Mgmt:
Host: bn303
AccessMethod: ssh # ssh or capi
SshUsername: admin # default admin
ChassisType: modular # fixed or modular
CapiProtocol: https
~/py @arst1.sjc> python test.py test.yaml
bn303
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