debug-hooks: include unit/hook in PS1

debug-hooks: include unit/hook in PS1

Set a useful bash prompt, including the
unit and hook names. The tmux window name
gets truncated, so that's not super useful.

Fixes bug #1212903

https://code.launchpad.net/~axwalk/juju-core/lp1212903-debug-hooks-prompt-take2/+merge/180470

(do not edit description out of merge proposal)

[axw, 2013-08-16 04:54:14]

Please take a look.

[thumper, 2013-08-16 05:03:44]

LGTM - the code looks fine, did you test it interactively?

[axw1, 2013-08-16 05:20:09]

On 2013/08/16 05:03:44, thumper wrote:
> LGTM - the code looks fine, did you test it interactively?

I did indeed (I probably would've missed the PS1 reset issue otherwise)

[jameinel, 2013-08-18 12:44:29]

It looks a bit odd that we expand the ENV vars early. It might not be an actual
problem, but it does seem strange.

Did you fire multiple concurrent hooks to make sure it didn't overwrite the
prompt in the other terminal?

https://codereview.appspot.com/13044043/diff/1/worker/uniter/debug/server_tes...
File worker/uniter/debug/server_test.go (right):

https://codereview.appspot.com/13044043/diff/1/worker/uniter/debug/server_tes...
worker/uniter/debug/server_test.go:203: c.Assert(contents, jc.Contains,
fmt.Sprintf(`PS1="%s:%s %% "`, s.ctx.Unit, hookName))
This looks like you are expecting the PS1 line to read
 "unit-0:db-relation-changed %"

I would have thought it would read:

"$JUJU_UNIT_NAME:$JUJU_HOOK_NAME"

Are we expanding the $* stuff early rather than late?

It would seem like this would cause problems when having multiple hooks firing,
but maybe we rewrite the shell script on every hook?

[axw1, 2013-08-19 01:01:03]

On 2013/08/18 12:44:29, jameinel wrote:
> It looks a bit odd that we expand the ENV vars early. It might not be an
actual
> problem, but it does seem strange.

It doesn't matter. Each time a debug hook session is started, the server creates
a new temporary directory. The env.sh script is written to this temporary
directory and sourced only by the client for that session.

> Did you fire multiple concurrent hooks to make sure it didn't overwrite the
> prompt in the other terminal?

I didn't, but how would you? Aren't hooks serialised?

>
https://codereview.appspot.com/13044043/diff/1/worker/uniter/debug/server_tes...
> File worker/uniter/debug/server_test.go (right):
> 
>
https://codereview.appspot.com/13044043/diff/1/worker/uniter/debug/server_tes...
> worker/uniter/debug/server_test.go:203: c.Assert(contents, jc.Contains,
> fmt.Sprintf(`PS1="%s:%s %% "`, s.ctx.Unit, hookName))
> This looks like you are expecting the PS1 line to read
>  "unit-0:db-relation-changed %"
> 
> I would have thought it would read:
> 
> "$JUJU_UNIT_NAME:$JUJU_HOOK_NAME"
> 
> Are we expanding the $* stuff early rather than late?
> 
> It would seem like this would cause problems when having multiple hooks
firing,
> but maybe we rewrite the shell script on every hook?

Correct. The current environment is written to a temporary file for each
session, then that script is sourced by the tmux (debug hooks) client shell.

[fwereade, 2013-08-19 10:57:43]

LGTM, thanks