Wednesday, June 14, 2017

PowerShell + .psd1 files - decouple environment configuration data from code

What is environment configuration data?

Well, you might have heard the term 'configuration data' in usage with PowerShell DSC. The case for using configuration data is wherein all the input arguments are abstracted from the code being written so that this configuration data can be generated on the fly and passed to the underlying scripts or framework like DSC.

For some of our solutions being deployed at the customer site, we require a lot of input parameters e.g. different network subnets for management and storage networks, AD/DNS information etc.

Adding all these parameters to our input argument collector script was an error prone and tedious task since there were far too many input arguments. So instead of having a file to specify all input arguments was the preferred method.

This also helped us while troubleshooting the deployments since a local copy of the input arguments always persisted.

Thursday, March 02, 2017

PowerShell + AzureRM : Using Certificate based automated login

This is a long overdue post (previous one here) on how to use certificates to do an automated login to Azure Resource Manager. Not rocket science but easy to setup, so that you use a cert to authenticate to Azure RM automatically.

It seems the Azure docs are already up to date on how to do few bits involved in this, please read the section 'Create service principal with a certificate' in the docs.

The process is almost the same as mentioned in the docs, except the fact that when we do the role assignment, we instead assign the contributor role definition to the service principal, since we want the ability to manage the resources in Azure RM.
Also, we will author a function add it to our profile so that PowerShell authenticates automatically to Azure RM each time it opens. 
So let's begin with it:
  1. Create the self-signed certificate.

    If you are running this on Windows 8.1, then you have to use the script by MVP Vadims Podans from the gallery.

    # For OS below Windows 10, download the script and use that to generate the self-signed cert.
    Import-Module .\New-SelfSignedCertificateEx.ps1
    New-SelfSignedCertificateEx -StoreLocation CurrentUser -StoreName My -Subject "CN=AutomateLogin" -KeySpec Exchange
    $cert = Get-ChildItem -path Cert:\CurrentUser\my | where {$PSitem.Subject -eq 'CN=AutomateLogin' }

    Otherwise, if you are running Windows 10 then the builtin PKI module would suffice. Note - The cert created below has marked private key to be not exportable.

    Run below:

    $cert = New-SelfSignedCertificate -CertStoreLocation "cert:\CurrentUser\My" -Subject "CN=AutomateLogin" -KeySpec KeyExchange -KeyExportPolicy NonExportable

Tuesday, January 31, 2017

PowerShell : Trust network share to load modules & ps1


Do you have a central network share, where you store all the scripts or PowerShell modules ?
What happens if you try to run the script from a network share ? or if you have scripts (local) which invoke scripts or import PowerShell modules stored on this network share ?

Well you would see a security warning like below (Note - I have set execution policy as 'Unrestricted' not 'bypass' here):

Run a .ps1 from the network share

Well this is a similar warning, which you get when you download scripts from Internet.
As the message says run Unblock-File cmdlet to unblock the script and then run it, let's try it.