Problem this snippet solves:
This iRule uses the STATS profile to manage an LTM maintenance page response during maintenance windows.
Implementation details here: DevCentral - An F5 Technical Community
Code :
when HTTP_REQUEST {
set TITLE "iRule Maintenance Window Control"
set PROFILE_NAME "maintenance_window"
# Look for embedded commands to control the maintenance window.
switch -glob [string tolower [HTTP::uri]] {
"/enable*" {
# Extract the maintenance window day, start time, and end time from the URI.
# If not there, return an error message.
set params [split [HTTP::uri] "/"]
if { [llength $params] < 5 } {
HTTP::respond 200 content "
<center>
<title>$TITLE</title>
<h1 id="community-277779-toc-hId-1847774792">Usage: http://[HTTP::host]/enable/day_number/start_hour/end_hour</h1>
"
} else {
# Update the maintenance window values in the statistics profile.
STATS::set $PROFILE_NAME "day" [lindex $params 2]
STATS::set $PROFILE_NAME "start_time" [lindex $params 3]
STATS::set $PROFILE_NAME "end_time" [lindex $params 4]
HTTP::respond 200 content "
<center>
<title>$TITLE</title>
<h1 id="community-277779-toc-hId--704382169">Maintenance Window enabled</h1>
"
}
}
"/disable" {
# By zero'ing out the values in the statistics profile, the maintenance window is not enforced.
STATS::set $PROFILE_NAME "day" 0
STATS::set $PROFILE_NAME "start_time" 0
STATS::set $PROFILE_NAME "end_time" 0
HTTP::respond 200 content "
<center>
<title>$TITLE</title>
<h1 id="community-277779-toc-hId-1038428166">Maintenance Window disabled</h1>
"
}
"/check" {
# Return the current time and the current settings for the maintenance window
set day [STATS::get $PROFILE_NAME "day"]
set start_time [STATS::get $PROFILE_NAME "start_time"]
set end_time [STATS::get $PROFILE_NAME "end_time"]
set l [split [clock format [clock seconds] -format {%u %H %M}] " "]
set cur_day [lindex $l 0]
set cur_time [expr [expr [lindex $l 1]*100] + [lindex $l 2]]
HTTP::respond 200 content "
<center>
<title>$TITLE</title>
<h1 id="community-277779-toc-hId--1513728795">Current Date and time: $cur_day, $cur_time</h1>
<h1 id="community-277779-toc-hId-229081540">Maintenance Window: $day, $start_time - $end_time</h1>
"
}
"/usage" {
# Usage instructions for the commands
HTTP::respond 200 content "
<center>
<title>$TITLE</title>
<h1 id="community-277779-toc-hId-1971891875">Usage: http://[HTTP::host]/\[command\]</h1>
<table><tbody><tr><td><ul>
<li>/enable/day_of_week_number(1:mon-7:sun)/start_time(hhmm)/end_time(hhmm) - enable maintenance window.</li>
<li>/disable - disable maintenance window.</li>
<li>/check - check if in maintenance window.</li>
<li>/usage - display this usage message</li>
</ul></td></tr></tbody></table>
"
}
default {
# no secret command entered, so check the maintenance window
# Get the values from the statistics profile.
set day [STATS::get $PROFILE_NAME "day"]
set start_time [STATS::get $PROFILE_NAME "start_time"]
set end_time [STATS::get $PROFILE_NAME "end_time"]
if { ($day ne 0) and ($start_time ne 0) and ($end_time ne 0) } {
# Use the TCL "clock" command to get the current time settings.
set l [split [clock format [clock seconds] -format {%u %H %M}] " "]
set cur_day [lindex $l 0]
set cur_time [expr [expr [lindex $l 1]*100] + [lindex $l 2]]
if { ($cur_day eq $day) &&
($cur_time >= $start_time) &&
($cur_time <= $end_time) } {
# The current time is in the maintenance window, so either issue a HTTP::redirect here to a
# prettied up page, or you can do as I've done here, and return a HTML response direction
# to the client.
HTTP::respond 200 content "
<center>
<title>$TITLE</title>
<h1 id="community-277779-toc-hId--580265086">This site is down for maintenance, please come back at $end_time ...</h1>
"
} else {
# Not in maintenance window, so allow connection to continue to application.
}
}
}
}
}</center>
</center>
</center>
</center>
</center>
</center>