Developing a Bicep Validation Pipeline

Azure’s Bicep is Microsoft’s newer format for defining Azure resources as code. In terms of look and feel, it’s very similar to Terraform.. If one considers Bicep files as code, then it would be a natural step to ensure that code meets a certain level of quality. In addition to that level of quality, because Bicep is deploying infrastructure, we would want to ensure that infrastructure is well designed and has a chance of successfully deploying.

When Bicep started to be adopted by the team I was working in, I became involved in designing a process to meet those quality goals as well as reduce the number of deployment issues.

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Registering a VM with Multiple Azure DevOps Environments

Azure DevOps has the concept of Environments, a collection of resources which can be used during a pipeline. At the time of writing the only types of resources that can be used are Virtual Machines and Kubernetes resources. The official documentation on registering a VM resource doesn’t explicitly mention there being any issues with using the same resource across multiple environments, apart from “providing a unique name for the agent”. There’s an important consideration with how the registration process works relating to this.

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“Could not create SSL/TLS secure channel” error when using self-hosted Azure DevOps Agent

Recently the team I’m in has been getting into Microsoft’s new Bicep language. As part of a release pipeline, the infrastructure was being deployed – in this case an Azure App Service. Then the application code was being deployed using the standard “Azure App Service Deploy” task. At this particular task, it would error out:

Error: Could not complete the request to remote agent URL 'https://<App Service Name>.scm.azurewebsites.net/msdeploy.axd?site=<App Service Name>'.
Error: The request was aborted: Could not create SSL/TLS secure channel.

The pipeline was being run through our “Default” agent pool, which was a self-hosted agent.

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PowerShell Quality of Life Improvements – PS Repository

In the last post, we were able to create a Release Pipeline that takes checked and signed Powershell code and deploys it to target servers. In some situations, it may not be desirable or viable to have every server configured as a deployment target. Or there may be a need to have an additional amount of control of the modules that a server gets. To deal with these issues, we can look at setting up a PowerShell Respoistory as an intermediatory step.

Setting Up The Respository

The Respository can be as simple as a file share on a server. At the higher end of complexity, it can be a website running NuGet Gallery. For this case, I’ve gone simple. By using a file share, we negate the need for setting up API keys and the like that a NuGet Gallery would need.

Once the PowerShell Respoistory is created, it needs to be registered on the relevant targets. This is achieved using the Register-PSRepository cmdlet, as shown below:

Register-PSRepository -Name psqol -SourceLocation "\\svr14\psrepo\" -PublishLocation "\\svr14\psrepo\" -InstallationPolicy Trusted

If the InstallationPolicy value is set to “Untrusted”, then there will be a user prompt when attempting to install modules from the Repository.

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PowerShell Quality of Life Improvements – Release

Releasing a build is typically the final step in the process of developing code. For PowerShell, this takes the form of getting our signed scripts and modules onto target servers to be available for use. This can be easily achieved in Azure DevOps.

Deployment Groups/Targets

The deployment tasks will run on the targets will recieve the scripts. Before that, a Deployment Group needs to be created. This is done by navigating to Pipelines > Deplyment Groups and clicking “Add new deployment group”. The group needs to be given a name.

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PowerShell Quality of Life Improvements – Automatic Versioning

Once we start doing processes like putting PowerShell code into git repositories, signing it and effectively creating new versions of it, it becomes useful to be able to automatically manage the versioning of our scripts and modules. The version number acts as an easy visual indicator of whether the script is the latest or not.

Introducing Token Replacement

Since the version number will change with each “build”, we will want to put in some sort of place holder value – a token. In my sample module, I change the version value to reference this token:

# Version number of this module.
ModuleVersion = '#{fullVersion}#'

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PowerShell Quality of Life Improvements – Code Signing

PowerShell uses Execution Policies to control whether a script can be run or not. Some of these policies rely on scripts being digitally signed by a trusted publisher. By signing your scripts, you can look at implementing a more restrictive Execution Policy that increases security. The first step in this process is getting a certificate.

Code Signing Certificate

To sign your scripts, you need a special type of certificate, one for code signing. If your scripts will be for internal use only and your organisation has an internal PKI, then using a code signing certificate from that PKI will be enough. If you are writing scripts or modules for consumption by a broader audience, then you’ll need a code signing certificate from a 3rd party Certificate Authority.

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VMSA-2022-0007 – VMware Tools vulnerability

VMware have published a new security advisory relating to VMware Tools for Windows. It affects v10 and 11 of the Tools. The vulnerability allows a user with local admin rights in the guest OS to acquire system privileges.

The version with the fix for this vulnerability is 12.0.0. While this is a major version jump, from the release notes there doesn’t appear to be any major breaking changes. It still supports Windows as far back as 7 SP1/2008 R2 SP1.