Dealing with Redirects

We use a lot of redirects in my current environment.  I mean ALOT.  Currently we have 150.  While that doesn't seem like a big number in many ways each of these are loaded into the Web Servers memory each time it starts.  Often, every 6 months or so, I like to have these reviewed to see which ones are valid, and this is difficult since we have a tracking system for requests, and we store the files in source control but there is little visibility about which ones are actually in use.  Which led to my recent foray into PowerShell and XML.

I was asked recently about getting a list of the updated redirects for review.  Nothing new, again I do this every 6 months, mostly because some just get asked to deal with a specific marketing campaign, a scheduled event and we have a few that exist from when we updated our web site in July 2011.  Those update ones are there to point people who may have had links to information on the old site, to the locations on the new site.  At times even those age and need to be removed at some point.  Still getting the information wasn't simple since I needed to collate from multiple sources, until last week when I had some spare multi-task time in the afternoon and thought, "hey, I can do this in powershell!"

So I sat down and pulled the XML into a PowerShell variable so I could look at it:
 [xml]$redirectXML = Get-Content $redirectFile

From there I looked at the structure I was getting and looking through many of the nodes noticed that the one that was going to give me trouble was the system.webserver since that . notation typically means that you have another node.  Why Microsoft gives it that notation I don't know but this stumped me for awhile.  Until coming across an answer for something else I saw that when you have node names like that you use quote marks around them.  So while following the nodes down to the Rules section I wanted from the Redirect Map I came up with:
$rules= $redirectXMl.configuration."system.webServer".rewrite.rewriteMaps.rewriteMap.add

This gave me the first part, but then it was a simple matter to then pull out the actual rules:
$redirectUrl= $redirectXMl.configuration."system.webServer".rewrite.globalRules.rule

This helped a lot, so what I ended up doing was pulling these together then outputting them into a table delimited file so I could pull them into Excel.  In the end I came up with a fairly good script that pulled out what I wanted, it does need clean up and I would like to actually output into an Excel worksheet, but that is for later.  My basic script ended up being:


# Get the values that we will need from the command line

# So far I only need the path and name of the redirect file, the

# ApplicationHost.Config file

Param([string]$redirectFile)

# Constants that will be necessary

[string]$redirListDir = $null

[string]$redirectList = "redirectList.csv"

# Check that we have a file to pull redirects from

if( ($redirectFile -eq $null) -or ($redirectFile -eq "")) {
    "Make sure its the path including the name "
    "of the applicationHost.config that needs to be checked. Try something like "
    ".\redirectReview.ps1 C:\filelocation\applicationHost.config"
    "Thank you!"
    exit
}

# Check that we have a place to put the file at the end
if(($redirListDir -eq $null) -or ($redirListDir -eq "")) {
    if (Test-Path -Path "d:\temp") {
        $redirListDir = "d:\temp"
        "Using D:\Temp"
    }
    elseif (Test-Path -Path "c:\temp") {
        $redirListDir = "c:\temp"
        "Using C:\Temp"
    }
    else {
        "Cannot find a directory D:\temp or C:\temp. Create one and try again.`n"
        exit 
     }
}
$redirectListFile = Join-Path -Path $redirListDir -ChildPath($redirectList)

if (Test-Path $redirectListFile) {
    Remove-Item $redirectListFile -Force
}

# Open the file and put it in an XML format

[xml]$redirectXML = Get-Content $redirectFile

# Review the XML tags

# One of my old pointers

# $redirectXMl.configuration."system.webServer".rewrite.rewriteMaps

"Getting the Rewrite Maps"
# This gets all the rewrite Map redirects
$rules = $redirectXMl.configuration."system.webServer".rewrite.rewriteMaps.rewriteMap.add

"Now for the Global Rules"
# This gets all the rules that have been added
# Trying some different match formats that did not work
# $inputUrl = $redirectXMl.configuration."system.webServer".rewrite.globalRules.rule | % {$_.match)
# $redirectUrl = $redirectXMl.configuration."system.webServer".rewrite.globalRules.rule | % {$_.action}

$redirectUrl = $redirectXMl.configuration."system.webServer".rewrite.globalRules.rule

"Creating the output file"
# Output the claimed values into a CSV file that can be reviewed somewhere
$rules | % {
    $a = $_.key + "`t" + $_.value
    $a >> $redirectListFile
}
$redirectUrl | % {
    $b1 = ($_.match).OuterXML
    $b2 = ($_.action).OuterXML
    $b = $b1 + "`t" + $b2
    $b >> $redirectListFile
}