PS script to update cloudfront distribution

Update-CloudFrontDistribution-OriginPath.ps1

<#
.SYNOPSIS
  Updates the Cloudfront distribution origin path with the supplied version number

.DESCRIPTION
  Given a version number this script will retrieve the current distribution, extract the ETAG value, update the current-distribution.json file with the version number (for the OriginPath), 
  save the JSON and then update the distribution using the new file. A CloudFront invalidation is then created to expire all edge caches.

.PARAMETER version
    A value indicating the version number to be used e.g. 1.12.1

.PARAMETER id
    A value indicating the id of the distribution to update

.PARAMETER env
    A value indicating the environment that is being updated

.INPUTS
  None

.OUTPUTS
  None

.NOTES
  Version:        1.0
  Author:         Andy Robinson
  Creation Date:  2018-04-04
  Purpose/Change: Initial script development
  
.EXAMPLE
  Update-CloudFrontDistribution-OriginPath.ps1 -version 1.12.1
#>

param(
    [Parameter(Mandatory=$true)] 
    [string] $version,

    #[string] $id = "EC6SV4J7HMZTU",
    [string] $id = "E1HQKZHGF8T6GQ",

    [string] $env = "dev"
)

Write-Host "Version" $version
Write-Host "Id =" $id
Write-Host "Current path =" (Get-Location)
Write-Host "Env =" $env

$currentDistributionFilename = "current-distribution.json"
$distributionConfigFilename = "distribution-config-$($env).json"
$updatedistributionConfigFilename = "updated-distribution-config.json"
$getDistributionCommand = "aws cloudfront get-distribution-config --id $($id) --profile dev > $($currentDistributionFilename)"
$createInvalidationCommand = "aws cloudfront create-invalidation --distribution-id $($id) --profile dev --paths ""/*"""

Write-Host "Executing getDistributionCommand '$($getDistributionCommand)'"
Invoke-Expression $getDistributionCommand

#Grab the current ETAG so we can update the configuration
$currentDistribution = Get-Content ".\$($currentDistributionFilename)" -raw | ConvertFrom-Json
$etag =  $currentDistribution.ETag

Write-Host "Found ETAG = " $etag

#Load the new config and set the version number
$distributionConfig = Get-Content ".\$($distributionConfigFilename)" -raw | ConvertFrom-Json

#Find any OriginPath elements that start with /
foreach ($element in $distributionConfig.Origins.Items) {

    if ($element.OriginPath.StartsWith("/"))
    {
        Write-Host "Found origin element"
        $element.OriginPath = "/$($version)"
    }    
}

# Save the modified configuration 
Write-Host "Creating updated distribution file"
$distributionConfig | ConvertTo-Json -Depth 20 | set-content ".\$($updatedistributionConfigFilename)"

# Setup the update command
$updateDistributionCommand = "aws cloudfront update-distribution --id $($id) --distribution-config file://$($updatedistributionConfigFilename) --profile dev --if-match $($etag)"

# Update the distribution using the new file
Write-Host "Executing updateDistributionCommand '$($updateDistributionCommand)'"
Invoke-Expression $updateDistributionCommand

# Force a refresh on Cloudfront
Write-Host "Executing createInvalidationCommand '$($createInvalidationCommand)'"
Invoke-Expression $createInvalidationCommand