Re: Re(3): [Fab-user] Revert deployments

[Christian Vest Hansen]

As it happens, Fabric suits my needs perfectly, so I haven't really
spent any time shopping around.

I know there's a thing called Paver:
http://www.blueskyonmars.com/projects/paver/ though it seems to have a
broader scope.

There's also that thing that Zed Shaw is (was?) building.

I have never tried either, though.

On Mon, Jan 19, 2009 at 11:01 PM, Miguel A. Lamy <address@hidden> wrote:
> Hi Christian,
>
> I was rereading your post and thought if you think Fabric is the best tool to 
> do what I need to do.
>
>
> If you think Fabric is not that tool can you suggest me another one ?
>
> Thanks again.
>
> Miguel Lamy
> GEDI, SA
>
> Miguel A. Lamy on segunda-feira, 19 de Janeiro de 2009 at 19:41  wrote:
> :Hi Christian,
> :
> :I think I can figure out now a solution to my problem.
> :
> :Thanks a lot.
> :
> :Miguel Lamy
> :
> :
> :address@hidden on segunda-feira, 19 de Janeiro de 2009 at 19:06  wrote:
> :On Mon, Jan 19, 2009 at 7:03 PM, Miguel A. Lamy <address@hidden> wrote:
> :> Hi all,
> :>
> :> I am evaluating Fabric and a I'm bit lost sorry... I think I'm putting 
> dumb question.
> :>
> :> I want to deploy Java Web application into several servers. In the past I 
> used some shell scripts that
> :stoped
> :> myservers, rsynced my app to the servers, backuped the databases (Mysql, 
> SqlServer and Oracle) and started
> :> the application server (tipical Jboss and Oracle). I use ssh in all 
> servers with public keys.
> :>
> :> I was doing the deployment  server by server and sometimes the process 
> didn't run as expected and I have
> :> crashs during the startup of the application because of some program 
> errors or inconsistency in the
> :databases.
> :
> :A tool such as Fabric works best in homogeneous environments, ie. when
> :all database servers are alike and all application servers are alike.
> :In this mindset, any inconsistencies in the environment are bugs.
> :
> :When each server is different, then each server must be handled
> :differently. This encourages fiddling, and fiddling leads to mistakes,
> :and mistakes leads to... suffering.... in the form of down time, ahem.
> ::)
> :
> :That said, Fabric is a pretty generic remote automation tool. :)
> :
> :>
> :> So I thought may be I can use some tool out there that simplify that work 
> and revert my process with no
> :> pain...
> :>
> :> I read some documentation from Fabric site and from the github.com but 
> still don't know how can I run
> :> myscripts in a way that can "detect" errors in deployment and run some 
> rollback code that reverts errors
> :> during the deployment.
> :
> :Fabric cannot undo arbitrary shell commands.
> :
> :Fabric runs with a fail-fast mentality by default, but this can be
> :overwriten on most remote operations by setting a `fail` kwarg to
> :either "ignore" or "warn". When you invoke an operation, the call can
> :be wrapped with a `try ... except SystemExit` of sorts, and that will
> :give you a chance to do something when bad stuff happens.
> :
> :But what I usually do is to just implement a "rollback" command in my
> :fabfile, and when I see that my deployment have failed, I can then
> :decide whether to run it or not.
> :
> :>
> :> I understand that I can use variables to store command result status and 
> define rollback commands that can
> :be
> :> executed but my question is... can Fabric "detect" errors and 
> automatically execute rollback functions in
> :> case of some trouble ?
> :
> :An "error", in the sense of invoking some remote shell command, is
> :when that command returns with a code other than 0.
> :
> :Fabric detects this and acts upon it in accord to the "fail" kwarg for
> :that particular operation, which is "abort" by default.
> :
> :Aborting works by throwing SystemExit, and this is something that you
> :can catch. However, Fabric was not designed with this use case in
> :mind, to there is no additional information about what failed encoded
> :in that exception.
> :
> :>
> :> I want to deploy several servers and not be worried if one server didn't 
> deployed correctly at 2.00AM and
> :the
> :> application server didn't start because of that failure. That server 
> should automatically recover from that
> :> bad deploy, revert to the previous status so in the morning I can analyse 
> the errors and correct that
> :errors
> :> not worried that users can't run my application because of that failure.
> :
> :This is possible to do by calling your own "rollback" command in the
> :except clause mentioned above.
> :
> :>
> :> I'd appreciate any help given :-)
> :>
> :> (Sorry for my poor english)
> :>
> :> Miguel Lamy
> :>
> :>
> :>
> :> _______________________________________________
> :> Fab-user mailing list
> :> address@hidden
> :> http://lists.nongnu.org/mailman/listinfo/fab-user
> :>
> :
> :
> :
> :--
> :Venlig hilsen / Kind regards,
> :Christian Vest Hansen.
> :
>
>
>



-- 
Venlig hilsen / Kind regards,
Christian Vest Hansen.