PowerShell cmdlet for having Docker log in to ECR

Grant-ECRAccess.ps1

# Install the AWS tools for PowerShell, then drop this in e.g. your profile file.
# As a bonus it exports `$Env:ECRHOST` which you can use when e.g. tagging or
# pushing images.
function Grant-ECRAccess {
	[CmdletBinding()]
	param (
		[parameter()]
		[string]
		$ProfileName = 'default',

		[parameter()]
		[string]
		$Region = 'us-east-1'
	)

	$token = Get-ECRAuthorizationToken -Region $Region -ProfileName $ProfileName
	$segments = [System.Text.Encoding]::ASCII.GetString([System.Convert]::FromBase64String($token.AuthorizationToken)).Split(':')
	$hostname = (New-Object System.Uri $token.ProxyEndpoint).DnsSafeHost
	$Env:ECRHOST = $hostname
	docker login -u ($segments[0]) -p ($segments[1]) $hostname
}