Promoting Vision and Behavior through Validation

on Monday, August 19, 2019

Building out a new architecture requires many processes and behaviors to be re-evaluated and modified. Those changes take time to refine, communicate and become embedded within a departments teams. And, when it comes to changes within the understanding of how processes works, it’s a very slow process which takes a large amount of repetition of intentions in order to build a communal understanding of a larger vision. And, usually, a lot of the details get lost when you’re trying to shift your mindset from one large vision over to a new large vision. The small stuff doesn’t really sink in until the large stuff has taken root.

But, there are minor opportunities to help remind team members of those smaller details when implementing validation checks within your systems. Software developers do this all the time when developing websites for their end customers. But, it isn’t done as often for internal facing applications or infrastructure pieces. For example, Domino’s requires you to put in a telephone number when you order a pizza for delivery, because if their driver becomes lost they will need to call you. The error message on the Domino’s order form does say the field is required, but it also has a little pop-up tip of why it’s required. When was the last time you saw an internal facing application explain why it wants you to do something in a validation message?

Its difficult to know when it will be useful to put in the extra time to adjust an error message in order for it to be more informative. So being on the look out for anyone that is reporting an issue and directly saying, “I didn’t know we should do it that way” is very helpful in locating places where a little more attention could go a long way.

Here’s an example. This was the original error message:

Service Accounts should start with ISVC_, IUSR_, or SVC_. Domain Account = '{0}'. AD User and Group accounts can also be used. Service Accounts should not start with '{domain name}\'

And after the update, here’s the new error message:

Service Accounts should start with ISVC_, IUSR_, or SVC_. Domain Account = '{0}'. AD User and Group accounts can also be used. Service Accounts should not start with '{domain name}\'. Please see `serviceaccount guidelines` for more information.

And this is what `serviceaccount guidelines` provides:

Service Accounts

Service accounts cannot be over 20 characters long including the endings of 'Dev' and 'Test'. Because of that, the maximum allowed length is 16 characters, which should include the prefix.

Prefixes

    IUSR_   Stands for IIS User Account. Used with websites that are seen/used by end users.
    ISVC_   Stands for IIS Service Account. Used with webservices and webjobs.
    SVC_    Stands for Win Services Account. Used with Windows Services and Scheduled Tasks.

Example

    ISVC_OrgAppName{env}


When choosing names for accounts, try to avoid redundancies within the name. For example, IUSR_DoorWebApp{env} would have 2 redundancies. 'Web' is redundant because the prefix of 'IUSR_' indicates it's a top level web application. And, 'App' is redundant because the prefix of 'IUSR_' indicates it's a web application. Another example of redundancy would be to add 'Svc' in an 'ISVC_' account name, eg. 'ISVC_DoorSvc{env}'.

It’s a small addition, but it has two effects. First, it’s communicating out a group of standardized application types and how to signal to other’s what the role of your application is. It’s also empowering the team members to have the information necessary to make solid decisions without needing to reach out to other teams (who may be busy with other work).

It’s extra overhead to put together the extra documentation, but it can definitely be worth it.

Powershell: Using a file hash to test for a change

on Monday, August 12, 2019

The PowershellForGitHub module is great! But … sometimes it can be a bit verbose when it’s trying to help out new users/developers of the module. This isn’t a bad thing in any way, just a personal preference thing. And, the module owner, Howard Wolosky, is really open to suggestions. Which is great!

So, I opened a ticket (PowerShellForGitHub Issue #124) to explain my confusion over the warning messages. And, to be fair, I explained my confusion in a very confusing way. But, he was nice enough to work through it with me and we found that something we needed was a way to tell if someone had updated a settings file after downloading the module on their machine.

Enter, Get-FileHash.

This command looks like it’s been around for quite a while, but it does the classic job of creating a hash of a file. And, that hash can be stored in code, so that it can be used to check if a change in the file has occurred.

So, how to use the check.

Here’s the original code:

And, here’s the updated code using Get-FileHash:

PowerShellForGitHub–Adding Get-GitHubRelease

on Monday, August 5, 2019

PowerShellForGitHub is an awesome powershell module for interacting with the GitHub API. It has a wide set of features that are already implemented and its supported by Microsoft(!!). You can also tell the amount of care the maintainer, Howard Wolosky, has put into it when you dig into the code and read through the inline documentation, contributing documentation and telemetry support(!!). BTW, if you ever need to create a PII transmittable string, check it out: Get-PiiSafeString.

One of the features I was looking for the other day was the ability to retrieve a list of releases for a repository. (I was building a script to monitor the dotnet/core releases; in order to build an ASP.NET Core Hosting Bundle auto-installer.)

I submitted a pull request of the update last week and was really impressed with all the automation in the pull request processing. The first thing that surprised me was the integrated msftclas bot (Microsoft Contribution License Agreements), which posted a legal agreement form that I (or the company I represent) consent to give Microsoft ownership of the code we contribute. It was soo smooth and easy to do.

Next was the meticulous level of comments and review notes on the pull request. If he made all those comments by hand, holy moly! That would be amazing and I would want to praise him for his patience and level of detail. Hopefully, some of the comments were stubbed out by a script/bot; which would be a really cool script to know about.

So, I’m gonna go through the comments and see if I can update this pull request.

  • *facepalm* Wow, I really missed changing the name GitHubLabels.ps1 to GitHubReleases.ps1 in the .tests.ps1 file.
  • White space in .tests.ps1: Ahhh … I can better see the white space formatting style now.
  • Examples missing documentation: Hahaha! My mistake. It looks like I started writing them and got distracted.
  • Telemetery: I loved the note:

    For these, I think it's less interesting to store the encrypted value of the input, but more so that the input was provided (simply in terms of tracking how a command is being used).

    Thank you for pointing that out! It makes complete sense.

In summary, a big Thank You to Howard Wolosky and the Microsoft team for making this module! It was a huge time saver and really informative on how to write Powershell code in a better way.

Pester Testing Styles

on Monday, July 29, 2019

Pester is a great testing framework for Powershell. And it can be used in a variety of different testing styles: TDD, BDD, etc. I’m going to look at two different styles, both of which are perfectly good to use.

TDD’ish with BeforeAll / AfterAll

Lines 4 through 7 are used to ensure that module don’t get repeatable imported, when this tests are run as part of a Test Suite. However, they will allow modules to be reloaded if you are running the individual test file within VSCode. For the most part, they can be ignored.

In this more Test Driven Development style test

  • The Describe blocks name is the function under test
  • And each It test is labelled to describe a specific scenario it is going to test
  • All the logic for setting up the test and executing the test are contained within the It block
  • This relies on the Should tests to have clear enough error messages that when reading through the unit tests output you can intuit what was the failing condition

This is a very straight forward approach and it’s really easy to see how all the pieces are setup. It’s also very easy for someone new to the project to add a test to it, because everything is so isolated. One thing that can really help future maintainers of a project is to write much lengthier and more descriptive It block names than the ones in the example, in order to help clarify what is under test.

Some things to note:

In this setup, the BeforeAll script is used to configure the environment to be ready for tests that are about to be run. Over time, this function has been replaced with BeforeEach, but for this example I’m using BeforeAll. The BeforeAll is setting up some values that I want available when the test is run, or a variable I want available when the test is run. I put a prefix of $script: on the variable created within the BeforeAll function because I have seen behavior where the variable was no longer defined outside of the scope of BeforeAll.

The AfterAll is a corresponding block to the BeforeAll, and is pretty self explanatory. The interesting part of the these two blocks is that they have to be declared within the Describe block and not within the InModuleScope block. They will not be run if they are declared in the InModuleScope block.

BDD’ish with try / finally

Lines 10 and 11 are used to ensure that that module has been configured correctly (for normal usage … not specific to the tests) and ensuring that the module isn’t being reloaded when being run in a Test Suite.

In this more Behavior Driven Development style test

  • Uses the Describe block to outline the preconditions for the tests
  • Immediately following the declaration of the Describe block, it has the code which will setup the preconditions
  • Uses the Context block to outline the specific scenario the user would be trying
  • And, immediately following the declaration, it has the code which will execute that scenario
  • Uses the It blocks to outline the specific condition that is being tested.
  • This requires more code, but makes it clearer what condition actually failed when reviewing unit test output

This is not as straight forward of an approach, as different areas of the code create the conditions which are being tested. You might have to search around a bit to fully understand the test setup. It also adds a little more overhead when testing multiple conditions as you will be writing more It block statements. The upside of that extra work is that the unit test output is easier to understand.

Some things to note:

In this setup, variable scope is less of an issue because variables are defined at the highest scope needed to be available in all tests.

The BeforeAll/AfterAll blocks have also been replaced with try/finally blocks. This alternative approach is better supported by Pester, and it can also help new developers make a key insight into the way Pester tests are run: They are not run in parallel, but instead are run in order from top to bottom. Because of this, you can use some programming tricks to mock and redefine variables in particular sections of the code without having to worry about affecting the results of other tests.

Deleting cached metadata from local NuGet

on Monday, July 22, 2019

The Issue

This article will help you resolve a nuget issue that involves packages which have case-sensitive misspellings in their dependency lists. Here is a sample error message:

Install-Package : Unable to resolve dependency 'Microsoft.Extensions.COnfiguration.Builder'

The Conditions

This is a very specific scenario. So, it takes a couple of preconditions to create:

  • You have to have attempted installing the nuget package into a project.
  • And, the installation had to fail with the above message. Here’s a screen shot for more context.


  • The installation needs to leave your system with the metadata for the package downloaded, but the actual .nupkg is no where on disk.

The Solution

In this scenario, your package metadata cache (called the http-cache) has been updated with the packages dependency list. So, the next time you attempt to call nuget.exe; instead of fetching a fresh copy of the packages metadata from the source, it will use the cached version. To fix this, we’ll need to remove the cached metadata.

  1. Find the package metadata store on your computer (reference docs):

    nuget locals all –list


  2. Use the http-cache value provided, and open the folder in file explorer. And, then find the subfolder which matches the package source.


  3. Within the subfolder, find the package you’re looking for and delete it.


  4. Now, you are ready to reinstall the package from nuget using the latest metadata information.

RSAT Setup on Windows 10 1903 - 0x800f0954

on Monday, July 15, 2019

Windows 10 1803 was the last time that Windows 10 had a separate RSAT download bundle. This the note from the download page:

IMPORTANT: Starting with Windows 10 October 2018 Update, RSAT is included as a set of "Features on Demand" in Windows 10 itself. See "Install Instructions" below for details, and "Additional Information" for recommendations and troubleshooting. RSAT lets IT admins manage Windows Server roles and features from a Windows 10 PC.

This is great! It makes re-installation of the RSAT tools just a little bit easier; and a little bit more aligned with automation.

A very nice Microsoft MVP, Martin Bengtsson, saw this new direction for installation and built out an easy to use installation script written in powershell. Here’s a blog post on what it does and how to use it.

The download of the script, execution and setup would have been pretty easy except for one thing … Error 0x800f0954.

It turns out that you need to enable a Group Policy that will allow your machine to download the optional RSAT packages from Windows Update servers instead of your on-premise Windows Server Update Services.

Luckily, Prajwai Desai has already figured this out and has an easy to follow set of instructions to update your Group Policy and allow for the download to occur.

Basic Install-WindowsTaskTemplate

on Monday, July 8, 2019

I don’t install powershell scripts as Windows Tasks every day (any probably need to find a way for another system to manage that responsibility), so it’s easy to forget how to do them. Here’s a quick template to install a Windows Task on a remote machine:


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