[chef] Re: better windows client download script

[Adam Edwards < >]

Florian, can you tell us more about the specific issues that this script solves for you?

A challenge with using default objects in Windows from _vbscript_ to do the download has been their memory usage — they tend to read the entire msi package into memory, then make another copy in memory, and write it to disk. When running under WinRM, this fails if you don't increase shell memory quotas (and on Win2k12, there is a bug in Windows itself where overriding this value does not work :)). 

The best way to do this that I've found is to use powershell and access the .net WebClient class — like wget or curl, it streams the download in chunks and writes chunks to disk so that memory utilization is low and you never hit these limits. Unfortunately, powershell is only available by default on win2k8r2 and above, so if you have to work on other systems, this isn't a good option. However, this is how we worked around the WinRM shell limitation bug on Win2k12.

-Adam

From: Florian Hehlen < "> >
Reply-To: " "> " < "> >
Date: Tuesday, August 6, 2013 10:25 AM
To: " "> " < "> >
Subject: [chef] better windows client download script

Hi all,

 

I just wanted to share a _vbscript_ that I have found that seems to be better than the default one provided with the chef client. I have been struggling for a while now with the script that fails on some machines and not others. I admit the windows setup is not ideal where I am but it is likely that I am not the one.

 

The point is that this script tries a few different approaches before giving up. I have not fully appreciated how it does it… I was mostly happy that it works!

 

I found the script here:  http://www.ericphelps.com/scripting/samples/BinaryDownload/

 

Below is the drop-in replacement script that I slightly adapted to work with the chef code in

knife-windows-0.5.12\lib\chef\knife\core\windows_bootstrap_context.rb

 

strUrl = WScript.Arguments.Named("url")

strFile = WScript.Arguments.Named("path")

Const adTypeBinary = 1

Const adSaveCreateOverWrite = 2

Const ForWriting = 2

Dim web, varByteArray, strData, strBuffer, lngCounter, ado

    On Error Resume Next

    'Download the file with any available object

    Err.Clear

    Set web = Nothing

    Set web = CreateObject("WinHttp.WinHttpRequest.5.1")

    If web Is Nothing Then Set web = CreateObject("WinHttp.WinHttpRequest")

    If web Is Nothing Then Set web = CreateObject("MSXML2.ServerXMLHTTP")

    If web Is Nothing Then Set web = CreateObject("Microsoft.XMLHTTP")

    web.Open "GET", strURL, False

    web.Send

    If Err.Number <> 0 Then

        SaveWebBinary = False

        Set web = Nothing

        Wscript.Quit

    End If

    If web.Status <> "200" Then

        SaveWebBinary = False

        Set web = Nothing

        Wscript.Quit

    End If

    varByteArray = web.ResponseBody

    Set web = Nothing

    'Now save the file with any available method

    On Error Resume Next

    Set ado = Nothing

    Set ado = CreateObject("ADODB.Stream")

    If ado Is Nothing Then

        Set fs = CreateObject("Scripting.FileSystemObject")

        Set ts = fs.OpenTextFile(strFile, ForWriting, True)

        strData = ""

        strBuffer = ""

        For lngCounter = 0 to UBound(varByteArray)

            ts.Write Chr(255 And Ascb(Midb(varByteArray,lngCounter + 1, 1)))

        Next

        ts.Close

    Else

        ado.Type = adTypeBinary

        ado.Open

        ado.Write varByteArray

        ado.SaveToFile strFile, adSaveCreateOverWrite

        ado.Close

    End If

    SaveWebBinary = True