Why we need common system configuration managment (devops) tools?

stage #1 "God Mode"

stage #2 "Hell's tooling"

stage #3 'LITTLE CRASH'

Fabric!

Python library and command-line tool for streamining the use of SSH for application deployment or systems administration tasks

http://www.fabfile.org/

Jeff Forcier

@bitprophet

• paramiko
• pyinvoke

Author

Installation

pip install fabric

requires:

• ecdsa
• paramiko
• pycrypto

Example

#fabfile.py

from fabric.api import run

def list_directory():
    run('ls -la')

MacBook-Pro-Petr:fabr petrnuzhnov$ fab -H hostname.server.com list_directory -u username -p password
[hostname.server.com] Executing task 'list_directory'
[hostname.server.com] run: ls -la
[hostname.server.com] out: total 483168
[hostname.server.com] out: drwxr-xr-x. 41 username username      4096 Jun 16 07:22 .
[hostname.server.com] out: drwxr-xr-x.  4 root     root          4096 Dec 18  2014 ..
[hostname.server.com] out: -rw-------   1 username username     50498 Jun 16 10:00 .bash_history
[hostname.server.com] out: -rw-r--r--.  1 username username        18 Oct 16  2014 .bash_logout
[hostname.server.com] out: -rw-r--r--   1 username username       269 Jul 15  2015 .bash_profile
[hostname.server.com] out: -rw-r--r--   1 username username       174 Apr 15  2015 .bashrc
[hostname.server.com] out: drwxr-xr-x   2 username username      4096 Feb 27  2015 bin
[hostname.server.com] out: drwxr-xr-x   2 username username      4096 Oct  5  2015 Builds
[hostname.server.com] out: -rw-r--r--   1 username username    118135 May 11 03:08 temp.my
[hostname.server.com] out: drwxr-xr-x   3 username username      4096 May 10 03:25 .vim
[hostname.server.com] out: -rw-------   1 username username     13406 Jun 15 13:32 .viminfo
[hostname.server.com] out: -rw-r--r--   1 username username        90 Oct 29  2014 .vimrc

Main components

• fab - command line utility
• fabfile - file with described tasks
• env - singleton dict subclass, which contains all necessary data: hosts, roles, credentials and other userfull settings
• task - separate execution unit (e.g. function)

Env

fabric.static.env

Configuration dict which is shared between tasks

• env.hosts - list of hosts which will be involved
• env.user
• env.password
• env.key_filename - path to ssh private key path
• env.timeout - default timeout
• env.keepalive=1 (default=0)

...

Hosts definition

env.roledefs['web'] = ['host1', 'host2',..]
env.roledefs['db'] = ['host3', 'host4']

env.roledefs = {'web':{'hosts':['host1', 'host2',..],
                       'logs':'/var/log/django'}

                'db':{'hosts':['host2', 'host3',...],
                      'logs':'/var/log/mysql'}}

env.hosts = ['host1', 'host2', ...]

'username@hostname:port'

OR

SETTINGS

Simple env wrapper

def task():
    with settings(warn_only=True):
        #do something dangerous

def task():
    with settings(timeout=30):
        sudo('service mysqld restart')

def task():
    with settings(sudo_user=petrnuzhnov):
        run('cat ~/my_personal_file.txt')

Tasks defenition

# fabfile.py
def task1():
    """Task1 docstring"""
    pass

def task2():
    """Task2 docstring"""
    pass

def task_combined():
    """Task_combined docstring"""
    task1()
    task2()

def _not_a_task()
    print "I'm not a task function"

fab --list
Available commands:
    task1            Task1 docstring
    task2            Task2 docstring
    combined_task    Task_combined docstring

Task definition #2

# fabfile.py
from fabric.api import task, roles, run, env

@roles('web')
@task()
def stop_web():
    sudo('service nginx stop')

@roles('db')
@task()
def stop_db():
    sudo('service mysqld stop')

@task(default=True)
def stop_all():
    execute(stop_web)
    execute(stop_db)

def not_a_task()
    print "I'm not a task function"

fab --list
Available commands:

    stop_web
    stop_db
    stop_all