Getting the max value of the day from the datapoint in table widget for capacity planning

#!!! Requires Credential Manager 2.0 from the repository !!!#

Import-Module     CredentialManager

function          Send-Request               {
    param (
        $cred,
        $accessid    = $null,
        $accesskey   = $null,
        $URL                ,
        $data        = $null,
        $version     = '2'  ,
        $httpVerb    = "GET"
    )

    if ( $accessId -eq $null) {
        $accessId    = $cred.UserName
        $accessKey   = $cred.GetNetworkCredential().Password
    }

    <# Use TLS 1.2 #>
    [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12

    <# Get current time in milliseconds #>
    $epoch           = [Math]::Round(
        ( New-TimeSpan `
            -start (Get-Date -Date "1/1/1970") `
            -end (Get-Date).ToUniversalTime()).TotalMilliseconds
        )

    <# Concatenate Request Details #>
    $requestVars     = $httpVerb + $epoch + $data + $resourcePath

    <# Construct Signature #>
    $hmac            = New-Object System.Security.Cryptography.HMACSHA256
    $hmac.Key        = [Text.Encoding]::UTF8.GetBytes( $accessKey )
    $signatureBytes  = $hmac.ComputeHash( [Text.Encoding]::UTF8.GetBytes( $requestVars ) )
    $signatureHex    = [System.BitConverter]::ToString( $signatureBytes ) -replace '-'
    $signature       = [System.Convert]::ToBase64String( [System.Text.Encoding]::UTF8.GetBytes( $signatureHex.ToLower() ) )

    <# Construct Headers #>
    $auth            = 'LMv1 ' + $accessId + ':' + $signature + ':' + $epoch
    $headers         = New-Object "System.Collections.Generic.Dictionary[[String],[String]]"
    $headers.Add(      "Authorization", $auth              )
    $headers.Add(      "Content-Type" , 'application/json' )

    # uses version 2 of the API
    $headers.Add(      "X-version"    , $version           )

    <# Make Request #>
    $response        = Invoke-RestMethod `
        -Uri           $URL      `
        -Method        $httpVerb `
        -Body          $data     `
        -Header        $headers

    $result          = $response

    Return $result
}
function          Get-LMRestAPIObjectListing {
    param (
        $URLBase          ,
        $resourcePathRoot , # "/device/devices"
        $size = 1000      ,
        $accessKey        ,
        $accessId
    )

    $output  = @()
    $looping = $true
    $counter = 0

    while ($looping) {
        #re-calc offset based on iteration
        $offset = ($counter * $size) + 1

        $resourcePath    = $resourcePathRoot
        $queryParam      = "?size=$size&offset=$offset"
        $url             = $URLBase + $resourcePath + $queryParam

        # Make Request
        $response        = Send-Request `
            -accesskey    $accessKey    `
            -accessid     $accessId     `
            -URL          $url

        if ( $response.items.count -eq $size ) {
            # Return set is full, more items to retrieve
            $output     += $response.items
            $counter++

        } elseif ( $response.items.count -gt 0 ) {
            # Return set is not full, store date, end loop
            $output     += $response.items
            $looping     = $false

        } else {
            # Return set is empty, no data to store, end loop
            $looping     = $false

        }
    }

    write-output $output
}

#!!! Change to your company name !!!#
$company        = "yourCompanyHere"
$URLBase        = "https://$company.logicmonitor.com/santaba/rest"

# This will resolve to proper values if it's being run from inside LM
$accessID       = "##Logicmonitor.AccessID.key##"
$accessKey      = "##Logicmonitor.AccessKey.key##"

if ( $accessID -like "##*" )       {
    # Not being run from inside LM - populate manually for testing
    Import-Module     CredentialManager

    $Cred       = Get-StoredCredential -Target LogicMonitor
    $accessID   = $cred.UserName
    $accessKey  = $Cred.GetNetworkCredential().Password
}

#!!! Populate the pertinent ID numbers from the "Info" section of the LM objects
$deviceNumber     = 123
$dataSourceNumber = 456
$instanceNumber   = 789

#region Get collectors
$resourcePath   = "/device/devices/$deviceNumber/devicedatasources/$datasourceNumber/instances/$instanceNumber/data"

$response       = Get-LMRestAPIObjectListing `
    -resourcePathRoot $resourcePath          `
    -accessKey        $accessKey             `
    -accessId         $accessID              `
    -URLBase          $URLBase

To find the ID Numbers, you can build out the $resourcePath for the last few bits until you come across the pieces you need.  I develop in PowerShell ISE to allow me to explore the date more easily once I've populated it.