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 for details.
Note: If possible, try to always use a forward slash /
as the path separator,
especially when dealing with relative paths. A backward slash \
will work on
Windows and is the official Windows path separator, but when building from any
system that is not Windows, Packer will only treat slashes /
as path
separators, and treat backslashes as plain text. Which could lead to pathing
errors.
Basic Example
The example below is fully functional.
Configuration Reference
The reference of available configuration options is listed below. The only required element is either "inline" or "script". Every other option is optional.
Exactly one of the following is required:
inline
(array of strings) - This is an array of commands to execute. The commands are concatenated by newlines and turned into a single file, so they are all executed within the same context. This allows you to change directories in one command and use something in the directory in the next and so on. Inline scripts are the easiest way to pull off simple tasks within the machine.script
(string) - The path to a script to upload and execute in the machine. This path can be absolute or relative. If it is relative, it is relative to the working directory when Packer is executed.scripts
(array of strings) - An array of scripts to execute. The scripts will be uploaded and executed in the order specified. Each script is executed in isolation, so state such as variables from one script won't carry on to the next.
Optional parameters:
binary
(boolean) - If true, specifies that the script(s) are binary files, and Packer should therefore not convert Windows line endings to Unix line endings (if there are any). By default this is false.valid_exit_codes
(list of ints) - Valid exit codes for the script. By default this is just 0.
debug_mode
- If set, sets PowerShell's PSDebug mode in order to make script debugging easier. For instance, setting the value to 1 results in adding this to the execute command:elevated_execute_command
(string) - The command to use to execute the elevated script. By default this is as follows:This is a template engine. Therefore, you may use user variables and template functions in this field. In addition, you may use two extra variables:
env
(map of strings) - A map of key/value pairs to inject prior to the execute_command. Packer injects some environmental variables by default into the environment, as well, which are covered in the section below. Duplicateenv
settings overrideenvironment_vars
settings. This is not a JSON template engine enabled function. HCL interpolation works as usual.environment_vars
(array of strings) - An array of key/value pairs to inject prior to the execute_command. The format should bekey=value
. Packer injects some environmental variables by default into the environment, as well, which are covered in the section below.use_pwsh
(boolean) - Runpwsh.exe
instead ofpowershell.exe
. Defaults to false.This is a template engine. Therefore, you may use user variables and template functions in this field. If you are running on AWS, Azure, Google Compute, or OpenStack and would like to access the autogenerated password that Packer uses to connect to the instance via WinRM, you can use the
build
template engine to inject it using{{ build `Password` }}
. In HCL templates, you can do the same thing by accessing thebuild
variables For example:
execute_command
(string) - The command to use to execute the script. By default this is as follows:This is a template engine. Therefore, you may use user variables and template functions in this field. In addition, you may use two extra variables:
Path
: The path to the script to runVars
: The location of a temp file containing the list ofenvironment_vars
, if configured. The value of bothPath
andVars
can be manually configured by setting the values forremote_path
andremote_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
andelevated_password
(string) - If specified, the PowerShell script will be run with elevated privileges using the given Windows user.This is a template engine. Therefore, you may use user variables and template functions in this field. If you are running on AWS, Azure, Google Compute, or OpenStack and would like to access the autogenerated password that Packer uses to connect to the instance via WinRM, you can use the
build
template engine to inject it using{{ build `Password` }}
. In HCL templates, you can do the same thing by accessing thebuild
variables For example:
If you specify an empty elevated_password
value then the PowerShell
script is run as a service account. For example:
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 arebypass
,allsigned
,default
,remotesigned
,restricted
,undefined
,unrestricted
, andnone
.remote_path
(string) - The path where the PowerShell script will be uploaded to within the target build machine. This defaults toC:/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.
skip_clean
(bool) - Whether to clean scripts up after executing the provisioner. Defaults to false. When true any script created by a non-elevated Powershell provisioner will be removed from the remote machine. Elevated scripts, along with the scheduled tasks, will always be removed regardless of the value set forskip_clean
.start_retry_timeout
(string) - The amount of time to attempt to start the remote process. By default this is5m
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.pause_after
(string) - Wait the amount of time after provisioning a PowerShell script, this pause be taken if all previous steps were successful.
Parameters common to all provisioners:
pause_before
(duration) - Sleep for duration before execution.max_retries
(int) - Max times the provisioner will retry in case of failure. Defaults to zero (0). Zero means an error will not be retried.only
(array of string) - Only run the provisioner for listed builder(s) by name.override
(object) - Override the builder with different settings for a specific builder, eg :In HCL2:
In JSON:
timeout
(duration) - If the provisioner takes more than for example1h10m1s
or10m
to finish, the provisioner will timeout and fail.
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 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 ashyperv
,parallels
,qemu
,virtualbox
, andvmware
), 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 thewinrm
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 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 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.
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.
The above snippet should result in the following output on the Packer console:
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.
The above snippet should result in the following output on the Packer console: