The Power of PowerShell pipelining

Every now and again I come back to PowerShell, it's useful as a tool, simple, clean and while I can sometimes say its easy to use, many times I smack my head on the desk.  Working in a Windows environment PowerShell scripts make doing many things easier, though it usually takes me some time to work them out.

For example, I am trying to output some results from failures on running SSIS Tasks, but I only really need to know certain statuses, or in most cases just the failures.  Focusing on the failures there can be a lot of them, if something fails at the beginning EVERYTHING runs and can easily fill up the log.  So while a command like:

    $Results = &'C:\Program Files\Microsoft SQL Server\110\DTS\Binn\DTExec.exe' /Project $Path /Package "$File.dtsx"

Can give me a huge result set, do I really need to display a couple of hundred lines of errors to the console, or to the Test Driver?  No.

I wanted to only pull out the error details, I am skipping over the step where I know there are errors here (just to make it easy) and what I want are the details to notify someone that "Hey, something went wrong here!  Here are some examples, want to know more, log in to the box and do some research!!"

So at first I step through everything (that's how I understand where things are working) and first came up with this:

foreach ($_ in $Results)
{
if ($_ -match "Description")
{
$exec_errors += $_
}
}

Now that is way too long.  A lot of white space, plus do I really need to step through that much?  No I don't, thankfully PowerShell makes this easy, since $Results is an array, I can pipeline it and step through it to match only what I want:

    $Results|?{ $_ -match "Description" }

This gets me only the data I want to display, the rest of what you get for the error messages is meaningless to convey the details of what went wrong.  I pipeline the $Results array into ? which is shorthand for the Where-Object and within the curly braces put what it is I was looking before in my if statement, under my foreach.  So now instead of a 3 or so line statement (not quite counting the curly braces there) I have 1 line!  Yes, there can be only 1.

Still I need someplace to put those results:

    $exec_errors = $Results|?{ $_ -match "Description" }

Now, I have an array of just the details I want and using $exec_errors I can output only what I need to communicate:

Write-Output "Errors in execution: "
if ($exec_errors.length -ge 2) {
Write-Output "$exec_errors[0] `n $exec_errors.length - 1"
} else {
Write-Output $exec_errors
}

I will have to see about making a one-liner of the rest later on.

Sauce Connect Script

I am currently working with Sauce Labs and using their Cloud Based testing to work with some automation, what I wanted first was an easy way to handle starting up the tunnel to Sauce Labs.  This was a jar file so I tried a few other methods to set the environment up the way I want, but considering that most environments I am working with are Windows I figured may as well use the old stand by of PowerShell.

Here is my current version of the script, this just checks to see that the environment is set up so I can output the log files in the places I want, and checks if a job is running then just continues on and uses the existing one - for now.  I heavily comment code when I first write it, so it should be enough to answer most questions, if not comment here and let me know!

----

# Sauce Labs Connect script
# Description:
# This script checks and sees if there is an existing Job that has an open tunnel
# to Sauce Labs in the current session; because of the way PowerShell works you
# cannot easily detect what is running in another session.  Basically this script
# was intended to generate the necessary Tunnel and run the test scripts with
# fewer keystrokes
# Author: Michael Furmaniuk
# Last Updated: April 16, 2014

# Command line values, so there is no reliance on the Username and Access Key
# being set in the environment or in the configuration files (although if they already are...)
param([string]$u, [string]$k)
Set-StrictMode -v 2

#######################################
# Check and make sure some of the specific needs are met
# Sauce Connect
[string]$jobName = "sauceConn"
[string]$rootPath = ""
[string]$sauceLog = "sauceLog.log"
[string]$sauceReady = "sauceReady.log"
[string]$sauceJar = "C:\Sauce-Connect-jar\Sauce-Connect.jar"
# If necessary the following could be completed to make this easier to run, otherwise these are
# command line arguments given as $u $k
# [string]$u = ""
# [string] $k = ""

#######################################
# Start the Sauce Jar
function start-SauceConnectJar()
{
<#
.Synopsis
This function starts the Sauce Connect Jar utilizing some known and command line parameters
.Description
This function starts the Sauce Connect Jar utilizing some known and command line parameters
#>
[CmdLetBinding()]
Param(
[Parameter(Mandatory=$true)][string]$sauceLog,
[Parameter(Mandatory=$true)][string]$sauceReady,
[Parameter(Mandatory=$true)][string]$sauceJar,
[Parameter(Mandatory=$true)][string]$u,
[Parameter(Mandatory=$true)][string]$k
) #end param
Process
{
# Let's check and see what drives and temp files we have
if (Test-Path "C:\TEMP") {
$rootPath = "C:\TEMP"
} elseif (Test-Path "D:\TEMP") {
$rootPath = "D:\TEMP"
} else {
Write-Host "I can't seem to detect any disk drives here with a TEMP directory, that is a problem.`n"
exit
}
# Build up the file paths
$sauceLog =  $rootPath + "\" + $sauceLog
$sauceReady = $rootPath + "\" + $sauceReady
# If these already exist we want to remove them
if (Test-Path $sauceLog) {
Remove-Item $sauceLog
}
# Note: if this call fails then there is an existing job in another session
# need to somehow handle this and fail gracefully: this is a TODO
if (Test-Path $sauceReady) {
Remove-Item $sauceReady
}
# Start Sauce Connect and see what is returned for the process
# Build up the latter part of the script block
$commandLineOption = "-l $sauceLog -f $sauceReady -d"
# Now for the full command line
$scriptblock = [scriptblock]::Create("java -jar $sauceJar $u $k $commandLineOption")

# Now let's start this as a Job, next line is for debugging
# Write-Host "Starting Sauce Connect with: $($scriptblock).`n"
# Should now be suppressing the start text
$output = Invoke-Expression "start-job -name $jobName -ScriptBlock { $scriptblock } 2>&1"

# Check for the Ready File
while (!(Test-Path $sauceReady)) {
Write-Host "Sauce Connect is still starting...`n"
sleep(10)
}
# Next statement is for debugging
# Since you only get a Tunnel ID when the connection is complete using this as a defining
# point to know the tunne is up, next statement was for debugging
# Write-Host "Sauce Connect should be up...getting the Tunnel ID.`n"
# Now acually getting the Endpoint/Tunnel ID as a verification step
get-SauceEndPoint $sauceLog
}
}

#######################################
# Get the endpoint ID from the log
function get-SauceEndPoint()
{
<#
.Synopsis
This function scans the initial Sauce Connect log file for the EndPoint ID to pass back
.Description
This function scans the initial Sauce Connect log file for the EndPoint ID to pass back
to the User through the console, so it can be used by the User to access the active Tunnel.
At some point this may be used for further automation
#>
[CmdLetBinding()]
Param(
[Parameter(Mandatory=$true)][string]$sauceLog
) #end param
Process {
# Now that the Connection is up, and the Ready File is in place
# read the log file to get the Tunnel ID or endpoint in the case of Java
$runningLog = Get-Content $sauceLog
# Run a regex to get the endpoint line, only one in the file at a time
# when this script runs, then print this out so it can be used (or saved for something else later)
$myMatch = $runningLog -match "endpoint ID:\s.*$" | %{$_ -split "ID:\s"}
# Next statement was a way to message that the Tunnel is up, if not needed comment out
Write-Host "Endpoint ID this time is: $($myMatch[1])"
}
}

#######################################
# The Sauce branch depending on what is running,
# I can either start a new Job or shut it down as/if necessary
$jobs = Get-Job 2>&1
if ($jobs) {
if ($jobs.State -eq "Running") {
# There is an existing Job, either we want to stop it and restart or drop out
# Right now going with using an existing Tunnel
Write-Host "An existing job is running, quitting for now."
Write-Host "...but getting the EndPoint ID to be useful."
get-SauceEndPoint $sauceLog
exit
}
elseif ($jobs.Name -eq $jobName -and $jobs.State -eq "Completed") {
Write-Host "Found $($jobs.Name) that was $($jobs.State) getting rid of it...`n"
Remove-Job $jobName
# Now that the previous one is gone, let's move on
Write-Host "Removed the old job, so starting a new Tunnel.`n"
start-SauceConnectJar $sauceLog $sauceReady $sauceJar $u $k
} else {
Write-Host "Weird, found a job but its not running, it's $($jobs.State).`n"
}
} else {
# Shouldn't be any other states to worry about at this point
# so just start the Jar file and move along
Write-Host "Nothing running, so starting the Tunnel.`n"
start-SauceConnectJar $sauceLog $sauceReady $sauceJar $u $k
}