asterisk users - Dec 2005 - Hint: how to include dialplan files from remote systems

Every once in a while I find a nice, compact little project is good enough to
share to the rest of the user community as a single post.  Here's something
that I was happy worked as planned.  This is not particularly clever, but uses
some infrequently-used tricks of running system commands from within Asterisk in
two different ways: System and #exec.  File this away under the heading of
"Not really clever, but impresses management."

I've got a user community who doesn't want to log into their Asterisk
servers much, but they have general housekeeping tasks they want to perform on
their dialplan which is really just mapping usernames to extension (for SIP
tasks, so that "jwhorfin" ends up calling "Zap/g1/2939") 
This shouldn't involve them doing anything other than updating a file
somewhere.  They know how to put files on a webserver, so the trick was how to
make them able to edit this file on their "easy-to-use" webserver and
make it magically appear on the "somewhat opaque" Asterisk system.  I
gave them a template file for them to store on their well-understood and
internally accessible webserver, that they can edit with WordPad or other text
editors.  This means that they don't have to learn any significant processes
to update the list of user-to-number mappings if they know how to publish
something on their webserver.  Here's the template example:


; -- Start File --
; Template for usernames-to-numbers
; 
; Save in the "privatefiles" directory of the public
;  webserver, accessible by anyone.
;
; Comments start with the semi-colon character
;
; After making changes on this list and saving it
;  to the webserver, you must call ext. 2900 to 
;  cause the Asterisk system to update itself 
;  with the contents of this file.
; 
[username-to-numbers]
exten => jwhorfin,1,Dial(Zap/g1/2939)
exten => rnevada,1,Dial(Zap/g1/2988)
;
; -- end file --
;


So, in the dialplan, here's what I do to include this file (note that the
"echo" user is just to illustrate that other "names" can be
included in the chain of contexts manually):

; ...more extensions.conf above here.
;
[from-internet]
;
; If any calls come in to user "echo", play back an echo test
;
exten => echo,1,Set(TIMEOUT(absolute)=500
exten => echo,n,Echo
;
; Now, include any users that have been configured by the client..
;
; (watch out for accidental line wraps here!  Next two lines start with
"#")
#exec /usr/bin/curl -s
http://webserver.domain.com/privatefiles/username-to-numbers >
/etc/asterisk/username-to-numbers
#include username-to-numbers
include => username-to-numbers
;
;
; more extensions.conf below here...
;
;

Now, just as trivially clever is that in a different context (from their PBX) I
can allow them to dial a "special" number that allows the
administrator to re-load/re-parse this file at will:

;
[from-pbx]
;
exten => 2900,1,System(/usr/sbin/asterisk -rx "extensions reload")
;


Don't forget to add this set of 2 lines to asterisk.conf to allow the config
files to execute commands with "#exec":

[options]
execincludes=yes

Good luck!

JT

On Thu, Dec 01, 2005 at 06:51:54PM -0800, John Todd wrote:
> #exec /usr/bin/curl -s
http://webserver.domain.com/privatefiles/username-to-numbers >
/etc/asterisk/username-to-numbers
> #include username-to-numbers
Nice. However, what happens if curl takes longer than expected? your
reload waits for it.

And what if you get a broken copy? I figure you should generally fetch
to a temporary file and only replace the working copy if the download
was successful.

Something like (untested):

  filename=`mktemp`
  destination=/etc/asterisk/username-to-numbers
  wget -q -O$filename && cp $filename $destination
  rm $filename

This still won't report errors up, and won't do any single sanity
check, but you get my point.

-- 
Tzafrir Cohen         | tzafrir@jbr.cohens.org.il | VIM is
http://tzafrir.org.il |                           | a Mutt's  
tzafrir@cohens.org.il |                           |  best
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