Managing Windows Server 2012 Systems : Configuring Roles, Role Services, and Features (part 6) - Tracking installed roles, role services, and features

You can install roles, role services, and features by typing Install-WindowsFeature ComponentName at an elevated prompt, where ComponentName is the management name of the component to install as listed in Table 3 or Table 4. In the following example, you install DHCP Server and the DHCP console for managing DHCP Server on CorpServer15:

Install-windowsfeature dhcp -ComputerName corpserver15 -includemanagementtools

Here, you don’t need to include the –IncludeAllSubFeature parameter because DHCP Server doesn’t have any subordinate role services or features. As PowerShell works, you see a Start Installation progress bar. When the installation is complete, you see the result. The output for a successful installation should look similar to the following:

Success Restart Needed Exit Code      Feature Result
------- -------------- ---------      --------------

True    No             Success        {DHCP Server}

As you can see, the output specifies whether the installation was successful, whether a restart is needed, an exit code, and a list of the exact change or changes made. The exit code can be different from the Success status. For example, if the components you specify are already installed, the exit code is NoChangeNeeded, as shown in this example and sample output:

Success Restart Needed Exit Code             Feature Result
------- -------------- ---------             --------------

True    No             NoChangeNeeded        {}

Here, you see that Install-WindowsFeature was successful but didn’t actually make any changes. The Feature Result shows no changes as well.

You don’t have to explicitly name the component or components you want to install. Install-WindowsFeature accepts redirected output for component names, allowing you to use another command to get the name or names of the components you want to work with. For example, if you want to install multiple components, such as all .NET components across the multiple .NET Frameworks that are available, you could use Get-WindowsFeature to help you do this, as shown in the following example:

get-windowsfeature -name NET-* | install-windowsfeature

Here, you use Get-WindowsFeature to obtain a list of components with names that start with NET– and then pipe that list to Install-WindowsFeature. The result is that you install all .NET components across all available .NET frameworks.

Component installation doesn’t always succeed, and that’s a common reason that the server cannot be accessed, as shown in this example, with accompanying error text:

Success Restart Needed Exit Code      Feature Result
------- -------------- ---------      --------------
False   Maybe          Failed         {}

install-windowsfeature : WinRM cannot process the request. The following error
occurred while using Kerberos authentication: Cannot find the computer
corpserver15. Verify that the computer exists on the network and that the
name provided is spelled correctly.

Here, Windows Remote Management (WinRM) couldn’t connect to the remote computer. Typically, this occurs because the server is offline or otherwise unavailable. This also could occur if you entered an incorrect server name.

Inadequate user rights is another common reason for component installation to fail, as shown in this example, with accompanying error text:

install-windowsfeature : You do not have adequate user rights to make changes to
the target computer. If you are already a member of the Administrators group on
the target computer, the changes might have failed because of security restrictions
imposed by User Account Control. Try running Install-WindowsFeature in a Windows
PowerShell session that has been opened with elevated rights (Run as administrator).

Success Restart Needed Exit Code      Feature Result
------- -------------- ---------      --------------
False   No             Failed         {}

Normally, when you are using Windows PowerShell for administration, you’ll use an elevated, administrator prompt and your current credentials will pass through to remote computers you work with. However, if your account doesn’t have appropriate user rights, you need to provide different credentials and you can do this using the –Credential parameter. You’ll be prompted for the user’s password if you follow the –Credential parameter with a user name, as shown in this example:

Install-windowsfeature dns -credential "CPANDL\wrstanek" -includemanagementtools

Here, you simply type the password and press Enter when prompted to run the command with the named account’s permissions. Rather than enter credentials for an account each time you want to perform administration, you can store credentials and then refer to the stored credential, as shown in this example:

$cred = get-credential
install-windowsfeature dns -credential $cred -includemanagementtools

Here, you use Get-Credential to prompt for a user name and password, and then store those credentials in the $cred variable. Next, you refer to the stored credentials to install DNS. Because the credentials are stored for the duration of your current PowerShell session, you can refer to them as needed for additional administration as well.

To test the installation prior to performing that actual operation, you can use the –Whatif parameter, as shown in the following example:

get-windowsfeature -name BIT* | install-windowsfeature -whatif

If you run this command, you might be surprised to see that BitLocker components are included along with BITS components. To resolve this, you need to be more specific when specifying the component name to match. If you intend to install BitLocker and BitLocker Network Unlock, you can use the following command instead:

get-windowsfeature -name bitlock* | install-windowsfeature -whatif

If a restart is required to complete an installation, you can have Install-WindowsFeature restart the computer by including the –Restart parameter. For planning purposes, especially on highly active production servers, keep in mind that both successful and failed installations could require a restart.