Fabric¶
Fabric is a library for simplifying system administration tasks. Fabric is more focused on application level tasks such as deployment.
Install Fabric:
$ pip install fabric
The following code will create two tasks that we can use: memory_usage and
deploy. The former will output the memory usage on each machine. The
latter will ssh into each server, cd to our project directory, activate the
virtual environment, pull the newest codebase, and restart the application
server.
from fabric.api import cd, env, prefix, run, task
env.hosts = ['my_server1', 'my_server2']
@task
def memory_usage():
run('free -m')
@task
def deploy():
with cd('/var/www/project-env/project'):
with prefix('. ../bin/activate'):
run('git pull')
run('touch app.wsgi')
With the previous code saved in a file named fabfile.py, we can check memory usage with:
$ fab memory_usage
[my_server1] Executing task 'memory'
[my_server1] run: free -m
[my_server1] out: total used free shared buffers cached
[my_server1] out: Mem: 6964 1897 5067 0 166 222
[my_server1] out: -/+ buffers/cache: 1509 5455
[my_server1] out: Swap: 0 0 0
[my_server2] Executing task 'memory'
[my_server2] run: free -m
[my_server2] out: total used free shared buffers cached
[my_server2] out: Mem: 1666 902 764 0 180 572
[my_server2] out: -/+ buffers/cache: 148 1517
[my_server2] out: Swap: 895 1 894
and we can deploy with:
$ fab deploy
Additional features include parallel execution, interaction with remote programs, and host grouping.
