How to set target hosts in Fabric file

Question

I want to use Fabric to deploy my web app code to development, staging and production servers. My fabfile:

def deploy_2_dev():
  deploy(\'dev\')

def deploy_         


        

Answer 1

To explain why it's even an issue. The command fab is leveraging fabric the library to run the tasks on the host lists. If you try and change the host list inside a task, you're esentially attempting to change a list while iterating over it. Or in the case where you have no hosts defined, loop over an empty list where the code where you set the list to loop over is never executed.

The use of env.host_string is a work around for this behavior only in that it's specifying directly to the functions what hosts to connect with. This causes some issues in that you'll be remaking the execution loop if you want to have a number of hosts to execute on.

The simplest way the people make the ability to set hosts at run time, is to keep the env populatiing as a distinct task, that sets up all the host strings, users, etc. Then they run the deploy task. It looks like this:

fab production deploy

or

fab staging deploy

Where staging and production are like the tasks you have given, but they do not call the next task themselves. The reason it has to work like this, is that the task has to finish, and break out of the loop (of hosts, in the env case None, but it's a loop of one at that point), and then have the loop over the hosts (now defined by the preceding task) anew.