---
description: |
    The PowerShell Packer provisioner runs PowerShell scripts on Windows machines.
    It assumes that the communicator in use is WinRM.
layout: docs
page_title: 'PowerShell - Provisioners'
sidebar_current: 'docs-provisioners-powershell'
---

# PowerShell Provisioner

Type: `powershell`

The PowerShell Packer provisioner runs PowerShell scripts on Windows machines.
It assumes that the communicator in use is WinRM. However, the provisioner can
work equally well (with a few caveats) when combined with the SSH communicator.
See the [section
below](/docs/provisioners/powershell.html#combining-the-powershell-provisioner-with-the-ssh-communicator)
for details.

## Basic Example

The example below is fully functional.

``` json
{
  "type": "powershell",
  "inline": ["dir c:\\"]
}
```

## Configuration Reference

<%= partial "partials/provisioners/shell-config" %>

-   `elevated_execute_command` (string) - The command to use to execute the
    elevated script. By default this is as follows:

    ``` powershell
    powershell -executionpolicy bypass "& { if (Test-Path variable:global:ProgressPreference){$ProgressPreference='SilentlyContinue'};. {{.Vars}}; &'{{.Path}}'; exit $LastExitCode }"
    ```

    The value of this is treated as [configuration
    template](/docs/templates/engine.html). There are two available variables:
    `Path`, which is the path to the script to run, and `Vars`, which is the
    location of a temp file containing the list of `environment_vars`, if
    configured.

-   `environment_vars` (array of strings) - An array of key/value pairs to
    inject prior to the execute\_command. The format should be `key=value`.
    Packer injects some environmental variables by default into the
    environment, as well, which are covered in the section below. If you are
    running on AWS, Azure or Google Compute and would like to access the
    generated password that Packer uses to connect to the instance via WinRM,
    you can use the template variable `{{.WinRMPassword}}` to set this as an
    environment variable. For example:

    ``` json
      {
        "type": "powershell",
        "environment_vars": "WINRMPASS={{.WinRMPassword}}",
        "inline": ["Write-Host \"Automatically generated aws password is: $Env:WINRMPASS\""]
      },
    ```

-   `execute_command` (string) - The command to use to execute the script. By
    default this is as follows:

    ``` powershell
    powershell -executionpolicy bypass "& { if (Test-Path variable:global:ProgressPreference){$ProgressPreference='SilentlyContinue'};. {{.Vars}}; &'{{.Path}}'; exit $LastExitCode }"
    ```

    The value of this is treated as [configuration
    template](/docs/templates/engine.html). There are two available variables:
    `Path`, which is the path to the script to run, and `Vars`, which is the
    location of a temp file containing the list of `environment_vars`. The
    value of both `Path` and `Vars` can be manually configured by setting the
    values for `remote_path` and `remote_env_var_path` respectively.

    If you use the SSH communicator and have changed your default shell, you
    may need to modify your `execute_command` to make sure that the command is
    valid and properly escaped; the default assumes that you have not changed
    the default shell away from cmd.

-   `elevated_user` and `elevated_password` (string) - If specified, the
    PowerShell script will be run with elevated privileges using the given
    Windows user. If you are running a build on AWS, Azure or Google Compute
    and would like to run using the generated password that Packer uses to
    connect to the instance via WinRM, you may do so by using the template
    variable {{.WinRMPassword}}. For example:

    ``` json
    "elevated_user": "Administrator",
    "elevated_password": "{{.WinRMPassword}}",
    ```

    If you specify an empty `elevated_password` value then the PowerShell
    script is run as a service account. For example:

    ``` json
    "elevated_user": "SYSTEM",
    "elevated_password": "",
    ```

-   `execution_policy` - To run ps scripts on windows packer defaults this to
    "bypass" and wraps the command to run. Setting this to "none" will prevent
    wrapping, allowing to see exit codes on docker for windows. Possible values
    are "bypass", "allsigned", "default", "remotesigned", "restricted",
    "undefined", "unrestricted", "none".

-   `remote_path` (string) - The path where the PowerShell script will be
    uploaded to within the target build machine. This defaults to
    `C:/Windows/Temp/script-UUID.ps1` where UUID is replaced with a dynamically
    generated string that uniquely identifies the script.

    This setting allows users to override the default upload location. The
    value must be a writable location and any parent directories must already
    exist.

-   `remote_env_var_path` (string) - Environment variables required within the
    remote environment are uploaded within a PowerShell script and then enabled
    by 'dot sourcing' the script immediately prior to execution of the main
    command or script.

    The path the environment variables script will be uploaded to defaults to
    `C:/Windows/Temp/packer-ps-env-vars-UUID.ps1` where UUID is replaced with a
    dynamically generated string that uniquely identifies the script.

    This setting allows users to override the location the environment variable
    script is uploaded to. The value must be a writable location and any parent
    directories must already exist.

-   `start_retry_timeout` (string) - The amount of time to attempt to *start*
    the remote process. By default this is "5m" or 5 minutes. This setting
    exists in order to deal with times when SSH may restart, such as a system
    reboot. Set this to a higher value if reboots take a longer amount of time.

<%= partial "partials/provisioners/common-config" %>

## Default Environmental Variables

In addition to being able to specify custom environmental variables using the
`environment_vars` configuration, the provisioner automatically defines certain
commonly useful environmental variables:

-   `PACKER_BUILD_NAME` is set to the [name of the
    build](/docs/templates/builders.html#named-builds) that Packer is running.
    This is most useful when Packer is making multiple builds and you want to
    distinguish them slightly from a common provisioning script.

-   `PACKER_BUILDER_TYPE` is the type of the builder that was used to create
    the machine that the script is running on. This is useful if you want to
    run only certain parts of the script on systems built with certain
    builders.

-   `PACKER_HTTP_ADDR` If using a builder that provides an http server for file
    transfer (such as hyperv, parallels, qemu, virtualbox, and vmware), this
    will be set to the address. You can use this address in your provisioner to
    download large files over http. This may be useful if you're experiencing
    slower speeds using the default file provisioner. A file provisioner using
    the `winrm` communicator may experience these types of difficulties.

## Combining the PowerShell Provisioner with the SSH Communicator

The good news first. If you are using the [Microsoft port of
OpenSSH](https://github.com/PowerShell/Win32-OpenSSH/wiki) then the provisioner
should just work as expected - no extra configuration effort is required.

Now the caveats. If you are using an alternative configuration, and your SSH
connection lands you in a \*nix shell on the remote host, then you will most
likely need to manually set the `execute_command`; The default
`execute_command` used by Packer will not work for you. When configuring the
command you will need to ensure that any dollar signs or other characters that
may be incorrectly interpreted by the remote shell are escaped accordingly.

The following example shows how the standard `execute_command` can be
reconfigured to work on a remote system with
[Cygwin/OpenSSH](https://cygwin.com/) installed. The `execute_command` has each
dollar sign backslash escaped so that it is not interpreted by the remote Bash
shell - Bash being the default shell for Cygwin environments.

``` json
  "provisioners": [
    {
      "type": "powershell",
      "execute_command": "powershell -executionpolicy bypass \"& { if (Test-Path variable:global:ProgressPreference){\\$ProgressPreference='SilentlyContinue'};. {{.Vars}}; &'{{.Path}}'; exit \\$LastExitCode }\"",
      "inline": [
        "Write-Host \"Hello from PowerShell\"",
      ]
    }
  ]
```

## Packer's Handling of Characters Special to PowerShell

The escape character in PowerShell is the `backtick`, also sometimes referred
to as the `grave accent`. When, and when not, to escape characters special to
PowerShell is probably best demonstrated with a series of examples.

### When To Escape...

Users need to deal with escaping characters special to PowerShell when they
appear *directly* in commands used in the `inline` PowerShell provisioner and
when they appear *directly* in the users own scripts. Note that where double
quotes appear within double quotes, the addition of a backslash escape is
required for the JSON template to be parsed correctly.

``` json
  "provisioners": [
    {
      "type": "powershell",
      "inline": [
          "Write-Host \"A literal dollar `$ must be escaped\"",
          "Write-Host \"A literal backtick `` must be escaped\"",
          "Write-Host \"Here `\"double quotes`\" must be escaped\"",
          "Write-Host \"Here `'single quotes`' don`'t really need to be\"",
          "Write-Host \"escaped... but it doesn`'t hurt to do so.\"",
      ]
    },
```

The above snippet should result in the following output on the Packer console:

    ==> amazon-ebs: Provisioning with Powershell...
    ==> amazon-ebs: Provisioning with powershell script: /var/folders/15/d0f7gdg13rnd1cxp7tgmr55c0000gn/T/packer-powershell-provisioner508190439
        amazon-ebs: A literal dollar $ must be escaped
        amazon-ebs: A literal backtick ` must be escaped
        amazon-ebs: Here "double quotes" must be escaped
        amazon-ebs: Here 'single quotes' don't really need to be
        amazon-ebs: escaped... but it doesn't hurt to do so.

### When Not To Escape...

Special characters appearing in user environment variable values and in the
`elevated_user` and `elevated_password` fields will be automatically dealt with
for the user. There is no need to use escapes in these instances.

``` json
{
  "variables": {
    "psvar": "My$tring"
  },
  ...
  "provisioners": [
    {
      "type": "powershell",
      "elevated_user": "Administrator",
      "elevated_password": "Super$3cr3t!",
      "inline": "Write-Output \"The dollar in the elevated_password is interpreted correctly\""
    },
    {
      "type": "powershell",
      "environment_vars": [
        "VAR1=A$Dollar",
        "VAR2=A`Backtick",
        "VAR3=A'SingleQuote",
        "VAR4=A\"DoubleQuote",
        "VAR5={{user `psvar`}}"
      ],
      "inline": [
        "Write-Output \"In the following examples the special character is interpreted correctly:\"",
        "Write-Output \"The dollar in VAR1:                            $Env:VAR1\"",
        "Write-Output \"The backtick in VAR2:                          $Env:VAR2\"",
        "Write-Output \"The single quote in VAR3:                      $Env:VAR3\"",
        "Write-Output \"The double quote in VAR4:                      $Env:VAR4\"",
        "Write-Output \"The dollar in VAR5 (expanded from a user var): $Env:VAR5\""
      ]
    }
  ]
  ...
}
```

The above snippet should result in the following output on the Packer console:

    ==> amazon-ebs: Provisioning with Powershell...
    ==> amazon-ebs: Provisioning with powershell script: /var/folders/15/d0f7gdg13rnd1cxp7tgmr55c0000gn/T/packer-powershell-provisioner961728919
        amazon-ebs: The dollar in the elevated_password is interpreted correctly
    ==> amazon-ebs: Provisioning with Powershell...
    ==> amazon-ebs: Provisioning with powershell script: /var/folders/15/d0f7gdg13rnd1cxp7tgmr55c0000gn/T/packer-powershell-provisioner142826554
        amazon-ebs: In the following examples the special character is interpreted correctly:
        amazon-ebs: The dollar in VAR1:                            A$Dollar
        amazon-ebs: The backtick in VAR2:                          A`Backtick
        amazon-ebs: The single quote in VAR3:                      A'SingleQuote
        amazon-ebs: The double quote in VAR4:                      A"DoubleQuote
        amazon-ebs: The dollar in VAR5 (expanded from a user var): My$tring
