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Category: Powershell

Creating A Powershell Module

Published 2017-06-30 by Kevin Feasel

Rob Sewell has a two-parter.  First, he looks at the SQL Server Diagnostics API:

The Diagnostic Analysis API allows you to upload memory dumps to be able to debug and self-resolve memory dump issues from their SQL Server instances and receive recommended Knowledge Base (KB) article(s) from Microsoft, which may be applicable for the fix.

There is also the Recommendations API to view the latest Cumulative Updates (CU) and the underlying hotfixes addressed in the CU which can be filtered by product version or by feature area (e.g. Always On, Backup/Restore, Column Store, etc).

I have written a module to work with this API. It is not complete. It only has one command as of now but I can see lots of possibilities for improvement and further commands to interact with the API fully and enable SQL Server professionals to use PowerShell for this.

This alone is quite interesting.  But then Rob shows how to turn this into a module, complete with tests:

I have been asked a few times what the process is for creating a module, using Github and developing with Pester and whilst this is not a comprehensive how-to I hope it will give some food for thought when you decide to write a PowerShell module or start using Pester for code development. I also hope it will encourage you to give it a try and to blog about your experience.

This is my experience from nothing to a module with a function using Test Driven Development with Pester. There are some details missing in some places but if something doesn’t make sense then ask a question. If something is incorrect then point it out. I plan on never stopping learning!

There are many links to further reading and I urge you to not only read the posts linked but also to read further and deeper. That’s a generic point for anyone in the IT field and not specific to PowerShell. Never stop learning. Also, say thank you to those that have taken their time to write content that you find useful. They will really appreciate that.

If you’re interested in developing professional-grade Powershell modules, this is a great starting point.

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Terminating Errors In Powershell

Published 2017-06-29 by Kevin Feasel

Adam Bertram explains terminating versus non-terminating errors in Powershell:

Non-terminating errors are still “errors” in PowerShell but not quite as severe as terminating ones. Non-terminating errors aren’t as serious because they do not halt script execution. Moreover, you can silence them, unlike terminating errors. You can create non-terminating errors with the Write-Error cmdlet. This cmdlet writes text to the error stream.

You can also manipulate non-terminating errors with the common ErrorAction and ErrorVariable parameters on all cmdlets and advanced functions. For example, if you’ve created an advanced function that contains a Write-Error reference, you can temporarily silence this as shown below.

Adam also shows how to convert a non-terminating error into a terminating error in your script.

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Bacpacing In Azure

Published 2017-06-28 by Kevin Feasel

Derik Hammer shows how to use a bacpac file to deploy an existing database to Azure SQL Database:

The recommended method for working with Azure is always PowerShell. The Azure portal and SSMS are tools there for your convenience but they do not scale well. If you have multiple databases to migrate, potentially from multiple servers, using PowerShell will be much more efficient. Scripting your Azure work makes it repeatable and works towards the Infrastructure as Code concept.

In this demonstration, the below steps will be used.

  1. Export the bacpac file to a local directory with sqlpackage.exe.

  2. Copy the bacpac to Azure Blob Storage with AzCopy.exe

  3. Use the PowerShell AzureRM module and cmdlets to create an Azure SQL Database from the bacpac file.

Derik shows the point-and-click way as well as the Powershell way.

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Remote Installation Of Powershell On SQL Server 2017

Published 2017-06-28 by Kevin Feasel

Tracy Boggiano has a script to install the SQL Server 2017 Powershell module via Powershell remoting:

Once the file is copied to the server locally you can use run the below script from your local machine to install SQL Server PowerShell 2017 for all user to use on the server.  The Get-CMSHosts function can be found on my blog here. You will need to download PsExec from here and extract to location on your local computer and provide the path.

NOTE: This is a hotfix that requires a RESTART. Be careful in PRODUCTION.

Click through for the script.

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PoshBot

Published 2017-06-27 by Kevin Feasel

Warren Frame shows off ChatOps with PoshBot:

We’re going to cover the basics to get up and running with PoshBot:

  • Create a Slack bot
  • Create a PoshBot configuration
  • Run PoshBot as a service
  • Write a PoshBot plugin
  • Use PoshBot

This might seem like a lot of work, but the configuration and service are a one time thing – Writing plugins is just like writing PowerShell functions and modules!

One of my mad scientist co-workers has put together a similar bot and it tells our DBA team how servers are doing.  It’s quite useful for system reconnaissance, particularly when all you have is a phone and a trouble ticket.

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Performance Comparison: Comparing Column Differences

Published 2017-06-23 by Kevin Feasel

Shane O’Neill has a column difference showdown:

The original post for this topic garnered the attention of a commenter who pointed out that the same result could be gathered using a couple of UNION ALLs and those lovely set-based EXCEPT and INTERSECT keywords.

I personally think that both options work and whatever you feel comfortable with, use that.

It did play on my mind though of what the performance differences would be…what would the difference in STATISTICS IO, TIME be? What would the difference in Execution Plans be? Would there even be any difference between the two or are they the same thing? How come it’s always the things I tell myself not to forget that I end up forgetting?

This may not be the most important thing to test, but it does show you a technique.

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Using dbatools To Back Up SQL Logins

Published 2017-06-23 by Kevin Feasel

Claudio Silva has a post showing how to use the Export-SqlLogin cmdlet to back up SQL Server logins on all databases on a set of instances:

With a database restore, the users are within a database and if their SID matches the SQL Login you are ready to go. But with the logins it is a different story!
If you have to reinstall the engine because your master database backup is corrupt or someone hs changed the login password and you want to put it back or even – maybe the most common scenario – you want to keep track of the login permissions you need to have them saved somewhere.

Imagine that you have to re-create a login and give all the permissions that it has, imagine that this login has multiple roles on different databases. Did you know that beforehand? Do you keep track of it? How much time would take to gather all that information from the application owner? How much time will you have to spend resolving all the permission issues until everything is running smoothly? How many tickets will need to be raised? How many users will this be affecting?

Read on for Claudio’s easy solution.

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Multi-Instance Powershell Queries

Published 2017-06-21 by Kevin Feasel

Jana Sattainathan shows an easy way of performing an operation against a number of SQL Server instances:

Today, I received a really simple request. There was an UPDATE statement that had to be run on quite a few databases in multiple instances.  This was for a vendor software we use and the statement was sent to me by a Helpdesk professional who manages the product.

You need to have the SQLPS (older) or the SQLSERVER (newer) PowerShell module installed.

Click through for the code.  If you want to extend this further, I’d look at using a Central Management Server to pull the instances and maybe looking at parallel processing if you have a large number of servers.

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JSON In Powershell

Published 2017-06-19 by Kevin Feasel

Adam Bertram shows an easy way of dealing with JSON data inside Powershell:

As the world continually becomes “eaten by software,” more and more services are being replaced by software. IT pros have most likely seen this in the form of software-defined everything. One of the premier components of this focus on software and with the continuing adoption of DevOps is application programming interfaces (APIs). All of these services needs to talk together and must provide a way for programs and users to interact with them. This is where APIs come in handy. But, what does this have to do with PowerShell and JSON, you ask?

APIs, more specifically REST APIs, return data when queried. This data is typically in the JSON format. JSON is a way of structuring data that makes it easy for software to consume. When working with PowerShell, Microsoft has provided some helpful tools to work with JSON called the ConvertTo-Json and ConvertFrom-Json commands. These commands allow you to quickly work with REST APIs or any other service that returns or accepts JSON as an input.

Read on for more details on how to use these commands.

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Cross-Platform Powershell Remoting

Published 2017-06-14 by Kevin Feasel

Anthony Nocentino shows how to enter Powershell sessions using OpenSSH-basted remoting:

Nothing special here, simple syntax, but the seasoned PowerShell remoting pro will notice that we’re using a new parameter here -HostName. Normally on Windows PowerShell you have the -ComputerName parameter. Now, I don’t know exactly why this is different, but perhaps the PowerShell team needed a way to differentiate between OpenSSH and WinRM based remoting. Further, Enter-PSSession now has a new parameter -SSHTransport which at the moment doesn’t seem to do much since remoting cmdlets currently use OpenSSH by default. But if you read the code comments here, it looks like WinRM will be the default and we can use this switch parameter to specify SSH as the transport.

Once we execute this command, you’ll have a command prompt to the system that passed as a parameter to -HostName. The prompt below indicates you’re on a remote system by putting the server name you’re connected to in square brackets then your normal PowerShell prompt. That’s it, you now have a remote shell. Time to get some work done on that server, eh? Want to get out of the session, just type exit.

It’s interesting to see how well Microsoft is integrating Linux support into Powershell (and vice versa, but that’s a different post).

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