Tcl script help -- include interface description in status message

Question

Hi there,
I'm trying to create a script that will email me when an interface goes down, and include the interface description in the email.  I've found a script that successfully emails me when the status changes, and I found another script that will parse for the interface description, but I can't seem to get them to work together.  I've mashed them up together into the below script:
# EEM policy that will monitor SYSLOG for Interface status changes.
# If UPDOWN message is detected, send an email with interface information.
### The following EEM environment variables are used:
### _email_server
### - A Simple Mail Transfer Protocol (SMTP)
### mail server used to send e-mail.
### Example: _email_server mailserver.example.com
# Register for a Syslog event. Event Detector: Syslog
# Match pattern for Interface Status change
::cisco::eem::event_register_syslog pattern "%LINK-3-UPDOWN"
# NAMESPACE IMPORT
namespace import ::cisco::eem::*
namespace import ::cisco::lib::*
# Set array for event_reqinfo
# Array is populated with additional event information
array set Syslog_info [event_reqinfo]
set msg $Syslog_info(msg)
# Set routername variable for use later
set routername [info hostname]
# Parse output for interface name
if { ! [regexp {: ([^:]+)$} $msg -> info] } {
    action_syslog msg "Failed to parse syslog message"
regexp {Line protocol on Interface ([a-zA-Z0-9]+)} $info -> interface 
# ------------------- cli open -------------------
if [catch {cli_open} result] {
error $result $errorInfo
} else {
array set cli $result
# Go into Enable mode
if [catch {cli_exec $cli(fd) "enable"} result] {
error $result $errorInfo
#Find interface description
if [catch {cli_exec $cli(fd) "show interface $interface | inc Description" } description] {
        error $description $errorInfo
#--------------------- cli close ------------------------
cli_close $cli(fd) $cli(tty_id)
set time_now [clock seconds]
set time_now [clock format $time_now -format "%T %Z %a %b %d %Y"]
# EMAIL MESSAGE
# This manually creates a text message with specific format to be used by the
# smtp_send_email command later to send an email alert.
# Ensure the following are configured:
# ip domain-name <domain.com>
# If a hostname is used for mailservername, ensure the following are configured:
# ip name-server <dns-server>
# ip domain-lookup
# NOTE: Change environment variable _email_server to your SMTP server
# The email below references the following variables:
# $routername: hostname of device
# $time_now: time when specific Syslog message was detected
# $msg: Syslog message received
set email_message "Mailservername: $_email_server
From: [email protected]
To: $_email_to
Cc:
Subject: EEM: Critical interface status change on $routername
This email is generated by EEM.
$time_now
$msg
$description
# Send email message
if {[catch {smtp_send_email $email_message} result]} {
set result "Email send failed"
} else {
set result "Email Sent"
# Debug message to check email transmission status
action_syslog msg "$result"
When I trigger an interface UPDOWN message, I'm getting the following error on the command line:
Oct 17 23:56:19.355 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl: can't read "interface": no such variable
Oct 17 23:56:19.355 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl:     while executing
Oct 17 23:56:19.355 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl: "cli_exec $cli(fd) "show interface $interface | inc Description" "
Oct 17 23:56:19.355 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl:     invoked from within
Oct 17 23:56:19.355 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl: "$slave eval $Contents"
Oct 17 23:56:19.355 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl:     (procedure "eval_script" line 7)
Oct 17 23:56:19.355 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl:     invoked from within
Oct 17 23:56:19.355 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl: "eval_script slave $scriptname"
Oct 17 23:56:19.359 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl:     invoked from within
Oct 17 23:56:19.359 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl: "if {$security_level == 1} {       #untrusted script
Oct 17 23:56:19.359 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl:      interp create -safe slave
Oct 17 23:56:19.359 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl:      interp share {} stdin slave
Oct 17 23:56:19.359 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl:      interp share {} stdout slave
Oct 17 23:56:19.359 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl: ..."
Oct 17 23:56:19.359 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl:     (file "tmpsys:/lib/tcl/base.tcl" line 50)
Oct 17 23:56:19.359 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl: Tcl policy execute failed: can't read "interface": no such variable
Can anyone help me figure out where I'm going wrong? 
Thanks in advance,
Brandon

Answer 1

Hi Dan,
Thanks for the reply.   I've made the changes you suggested but I'm still getting the error:
Oct 18 21:41:50.446 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl: can't read "interface": no such variable
Oct 18 21:41:50.446 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl:     while executing
Oct 18 21:41:50.446 HKT: %HA_EM-6-LOG: CriticalLinkStatus.tcl: "cli_exec $cli(fd) "show int $interface | inc Description""
Is there any additional debugging I could place in my script?  Normally I would try and print the variables after each line to see what's being populated, but I'm not sure how I can test that from within EEM.
--Brandon