New-CosmosDBHeader.ps1

function New-CosmosDBHeader {
    <#
    .SYNOPSIS
    Creates a Header for the CosmosDB API
    
    .DESCRIPTION
    Creates the basic header for all API calls with encrypted authorization string and correct date.
    If additional header entries are required, they can be added to the hashtable later.
    
    .PARAMETER Verb
    GET, POST, PUT, DELETE according to call
    
    .PARAMETER resourceName
    The human readable id of the resource - what the documentation says you should use but never uses
    
    .PARAMETER resourceId
    The rid of the resource - what the documentation saus you should NOT use, but is using ia all examples
    
    .PARAMETER resourceType
    dbs, colls, docs etc as specified by the call

    .PARAMETER OfferThroughput
    Request Units for collection creation.  
    
    .PARAMETER CosmosDBVariables
    This is the Script variable generated by Connect-CosmosDB - no need to supply this variable, unless you get really creative
    
    .EXAMPLE
    New-CosmosDBHeader -ResourceType dbs -Verb put
    
    .NOTES
    https://docs.microsoft.com/en-us/rest/api/documentdb/access-control-on-documentdb-resources
    #>
        [CmdletBinding(DefaultParameterSetName='Default')]
    param (
        [Parameter(Mandatory=$True,
        HelpMessage='GET, POST, etc.')]
        [string]$Verb,
        [Parameter(ParameterSetName='Name',
        Mandatory=$True,
        HelpMessage="Contains the relative path of the resource, as derived using the URI format. E.g. 'dbs/MyDatabase/colls/MyCollection/docs/MyDocument'")]
        [string]$resourceName,
        [Parameter(ParameterSetName='Rid',
        Mandatory=$false,
        HelpMessage="Contains the relative path of the resource, as derived using the URI format. E.g. 'dbs/MyDatabase/colls/MyCollection/docs/MyDocument'")]
        [string]$resourceId,
        [Parameter(Mandatory=$true,
        HelpMessage="Identifies the type of resource that the request is for, Eg. 'dbs', 'colls', 'docs'")]
        [string]$resourceType,
        [Parameter(Mandatory=$false,
        HelpMessage="Request Units for collection creation")]
        [int]$OfferThroughput,
        [Parameter(Mandatory=$false,
        HelpMessage="Use Connect-CosmosDB to create this Variable collection")]
        [hashtable]$CosmosDBVariables=$Script:CosmosDBVariables
    )
    
    begin {
       Test-CosmosDBVariable $CosmosDBVariables
    }
    
    process {
        $UTCDate = [DateTime]::UtcNow.ToString("r")
        $keyBytes = [System.Convert]::FromBase64String($CosmosDBVariables['Key'])
        $hmacSha256 = new-object -TypeName System.Security.Cryptography.HMACSHA256 -ArgumentList (,$keyBytes)
        [string]$Payload = "{0}`n{1}`n{2}`n{3}`n{4}`n" -f $Verb.ToLowerInvariant(),$resourceType.ToLowerInvariant(),$resourceId.ToLowerInvariant(),$UTCDate.ToLowerInvariant(),''
        $hashPayLoad = $hmacSha256.ComputeHash([Text.Encoding]::UTF8.GetBytes($PayLoad.ToLowerInvariant()))
        $signature = [System.Convert]::ToBase64String($hashPayLoad)
        [string]$authorizationFormat = 'type={0}&ver={1}&sig={2}' -f $CosmosDBVariables['keyType'],$CosmosDBVariables['tokenVersion'],$signature
        $header=@{
            "authorization" = [uri]::EscapeDataString($authorizationFormat)
            "x-ms-version" = "2015-12-16"
            "x-ms-date" = $UTCDate
            "Content-Type" = "application/json"
            }
        if ($OfferThroughput) { $header.add("x-ms-offer-throughput", $OfferThroughput) }
    }
    
    end {
        $header
    }
}