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Ben Piper

Installing PowerShell Core on Amazon Linux

·406 words·2 mins
Uncategorized Amazon Linux Powershell 2018
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Ben Piper
Author
Ben Piper
Wiley bestselling author — 100k+ copies, AWS Solutions Architect Associate (SAA) & Cloud Practitioner (CLF) bestsellers, 7+ books. 45 Pluralsight courses (4.7-star, 3,003 ratings). 10+ yrs 100% remote, solo CCNP ENCOR.

In preparation for my latest course in the AWS Networking Deep Dive series, I wanted to install PowerShell Core on an Amazon Linux instance to test out cross-platform compatibility for some scripts.

Specifically, I wanted to see if I could use methods in the System.Net.Dns class to perform name resolution. The dnsclient PowerShell module provides some cmdlets for this very purpose, but that module is Windows-only, and I needed something that would work on across different platforms.

To my surprise, it wasn’t as easy as just running sudo yum -y install powershell. Fortunately, it wasn’t as difficult as building from source. Here’s what I did:

Install the dependencies
#

sudo yum install -y curl libunwind libicu libcurl openssl libuuid.x86_64

Download the installation script
#

This script just fetches the tarball and extracts it to /opt/microsoft/powershell

wget https://raw.githubusercontent.com/PowerShell/PowerShell/master/docker/InstallTarballPackage.sh

Set the script to be executable
#

chmod +x InstallTarballPackage.sh

Run the script, specifying the PowerShell version (6.0.1) and package tarball as the arguments:

sudo ./InstallTarballPackage.sh 6.0.1 powershell-6.0.1-linux-x64.tar.gz

If you want to install a specific version (like the latest), then refer to the releases on the PowerShell repo.

Run PowerShell!
#

The command is pwsh, as in “Present Working SHell” (clever points). Be sure to use sudo, as it does require root privileges:

sudo pwsh

Get Your .NET On
#

The whole point of this exercise was to see if I could use .NET to perform DNS name resolution without any of the cmdlets in the Windows-only dnsclient module. Did it work? Let’s see.

PowerShell v6.0.1
Copyright (c) Microsoft Corporation. All rights reserved.

https://aka.ms/pscore6-docs
Type 'help' to get help.
PS /home/ec2-user> [System.Net.Dns]::GetHostAddresses("benpiper.com").IPAddressToString 
52.205.213.4

Yes indeed! Of course, I can still use the usual PowerShell tricks to extract just the data I want:

PS /home/ec2-user> [System.Net.Dns]::GetHostByName("pluralsight.com") | Select-Object AddressList

AddressList
 -----------
 {54.213.174.143, 35.164.44.204, 52.39.160.43}

I can also drill down to pick out just the first IP address in the list:

PS /home/ec2-user> ([System.Net.Dns]::GetHostByName("pluralsight.com")).AddressList[0].IpAddressToString
54.213.174.143

Run it again, and I get a different address:

PS /home/ec2-user> ([System.Net.Dns]::GetHostByName("pluralsight.com")).AddressList[0].IpAddressToString
52.39.160.43

Looks like round-robin DNS! But will this command work cross-platform? Let’s try it on my Windows 10 machine:

PS C:\Users\admin> ([System.Net.Dns]::GetHostByName("pluralsight.com")).AddressList[0].IpAddressToString
35.164.44.204

Yes! This is exactly why I chose PowerShell. The same command that works on Linux also works on Windows, which makes it perfect for an OS-agnostic course.

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