Re: [Fab-user] Deploying to multiple sets of hosts

[Nathan Nobbe]

Brandon,

Cool stuff, I was able to get this example from the answer on SO

http://stackoverflow.com/questions/15841024/python-fabric-no-host-found-must-manually-set-env-host-string

working pretty easily with multiple hosts, and I see the power here, but now I'm using python at the command line instead of fab. Can execute be used within fabric tasks to change the set of hosts and run new actions on the new hosts?

thanks,

-nathan

On Fri, Oct 25, 2013 at 9:51 PM, Brandon Whaley <address@hidden> wrote:

I prefer using execute: http://docs.fabfile.org/en/1.8/api/core/tasks.html?highlight=execute#fabric.tasks.execute

On Oct 25, 2013 7:55 PM, "Gilgamezh" <address@hidden> wrote:

El 25/10/13 19:20, Nathan Nobbe escribió:

Hi everyone,

I've recently started using Fabric (any Python for that matter)! So far
I'm loving Fabric compared to Capistrano, which is next to useless
outside of Ruby projects that I can tell.

I have hit a snag with Fabric though, and I'm surprised nobody else
seems to have dealt with it. I've got sets of nodes that comprise an
'environment'. For example, 2 boxes are used as db servers, 2 boxes as
application servers (not exactly my setup, but that's the idea).

Now I can have 2 tasks for this with @host decorators that map the hosts
to the deployment logic, however, since there is no way to change the
hosts within a task, I have to make 2 separate calls to fab on the CLI.

The problem is, I have several sets of nodes and the order of operations
in the deployment is itself some logic I would like to encapsulate. Best
approach I have so far is to place the fab calls into a BASH script.

I'm shocked that there's no way to change hosts within a task, and
moreover that this desire hasn't arisen before. Is there some way to
change the hosts mid-task? I can't find anything on Google or
Stackoverflow. Or am I thinking about this the wrong way? Seems like
grouping the hosts the way I have makes sense. I took a look at roles,
but I don't think that's any different than say an @host decorator with
the 'db' servers for example.

Your help appreciated!

thanks,

-nathan

Hi!

roles are in the env dict. You can do this:

env.roledefs.update({
    'webserver': ['www1', 'www2'],
    'dbserver': ['db1']
})

then.....

for server in env.roledefs['webserver']:
   do something
for server in env.roledefs['dbserver']:
   do something.

In all the cases you can set a specific host

for example:

with settings(host_string='somehost.domain'):
   do some

it's just python! :D

More in:
http://docs.fabfile.org/en/1.8/api/core/decorators.html?highlight=roledefs
http://docs.fabfile.org/en/1.8/usage/env.html?highlight=roledefs
http://docs.fabfile.org/en/1.8/usage/execution.html?highlight=roledefs


regards!

Gilgamezh.

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