Copy a File From Resource Element to a VM

Copying a File From a Resource Element to a Guest VM

This workflow is useful as a utility workflow that can convert a file stored in a resource element into a file on a guest VM.  This is done first by saving the file from the resource element to the local file system of the vRealize Orchestrator appliance.  From there it is copied into a guest VM’s file system using the VMware Host Guest Filesystem (HGFS) interface of VM Tools.  In some secure environments this functionality may be blocked in the VMX settings of the virtual machine, so it is a good idea to check to make sure HGFS is not blocked before attempting to use this interface. 

Assuming that using HGFS to copy files to the guest VM is not a problem, then this workflow serves as a good way to copy script files from resource elements to virtual machines.  A benefit of this approach is that network connectivity is not required from the vRealize Orchestrator instance to the guest VM, making it a better candidate than SSH in certain instances.  If HGFS is blocked but connectivity from the vRealize Orchestrator appliance to the guest VM is not, then SSH may be a better candidate as the transfer method. 

There are other ways to accomplish this functionality, such as placing the files on a commonly accessible HTTPS web server and copying it locally to the VM from that location.  Similarly, files can be pre-staged in VM templates to make them accessible, although this approach is not recommended because it couples build artifacts with VM templates meaning that any change to a build artifact would require a change to the VM template.  A third way is to store files on a commonly accessible NFS or CIFS share, issue commands to the VM to mount this share at build time, and copy or execute scripts from that location at runtime.  Any of these approaches are valid, and which one is ultimately chosen depends on the specific characteristics of the environment in which the task is to be accomplished.

CREATE THE WORKFLOW

Create a new workflow with the name “Copy Resource To Guest”.  We are going to place this workflow in the /Examples/Tools/Scripts folder.

INPUTS

The workflow should have five inputs:

Input	Type	Description
TargetResource	ResourceElement	The resource element containing the file that should be copied to the guest VM
TargetDirectoryOnGuest	String	The directory in the guest VM’s filesystem where the target resource should be placed.
VMUsername	String	Admin username for the machine that has permissions to execute a process in the operating system
VMPassword	SecureString	The password for the admin username provided in the vmUsername input
VM	VC:VirtualMachine	A reference to the virtual machine in which we want to execute a program

Figure 1. Workflow inputs for the "Copy Resource To Guest" workflow

In the workflow designer, these inputs will look as follows:

Figure 2. Inputs for the "Copy Resource To Guest" workflow

ATTRIBUTES

We will be assigning five attributes for this workflow:

Attribute	Type	Description	Value
outFilename	String	Stores the full filename on the vCO server after it is written from resource element locally	[Blank]
guestfilePath	String	Stores the full filename on the guest VM operating system that will be used to write the file to the guest.	[Blank]
overwrite	Boolean	Overwrite the file if it already exists	Yes/True
copyResult	Boolean	Will be true if the copy operation was successful	No/False
errorCode	String	Return error string if there is an error copying the file	“Guest file copy operation failed!”

Figure 3. Attributes for the "Copy Resource To Guest" workflow

In the workflow designer, these will look as follows:

Figure 4. Attributes for the "Copy Resource To Guest" workflow

OUTPUTS

This workflow has one output, which is the Guest file name of the file copied to the guest.

Output	Type	Description
GuestFileName	String	Filename of the file copied to the guest VM.

Figure 5. Workflow outputs for the "Copy Resource To Guest" workflow

In the workflow designer, the outputs will look as follows:

Figure 6. Outputs for the "Copy Resource To Guest" workflow

SCHEMA

The workflow consists of multiple steps.  First we will write the resource to a file locally on the vRealize Orchestrator appliance.  Then we will initiate a copy of that file from the vRealize Orchestrator appliance to the guest virtual machine.  If the copy was unsuccessful, we’ll throw an error.  If it was successful, we’ll set the output of the workflow to the guest file name and finish.

The schema we will build will look like this:

Figure 7. Workflow schema for the "Copy Resource To Guest" workflow

Write Resource

Create the Write Resource step by dragging and dropping a new Scriptable task node on to the schema canvas between the start and end nodes.  Set the name of the step to “Write Resource”.

Wire the inputs, attributes, and outputs in the following manner.

Inputs

Local Parameter	Source Parameter	Type
TargetResource	TargetResource	ResourceElement
TargetDirectoryOnGuest	TargetDirectoryOnGuest	String

Outputs

Local Parameter	Source Parameter	Type
outFileName	outFileName	String
guestFilePath	guestFilePath	String

The visual binding on the “Write Resource” step should look as follows:

Figure 8. Visual binding for the "Write Resource" step in the "Copy Resource To Guest" workflow

For the scripting content of the Write Resource task, enter the following block of code into the scripting tab:

var useForwardSlash = TargetDirectoryOnGuest.indexOf("/") > -1 || TargetDirectoryOnGuest.indexOf("\\") == -1;
var slash = "/";
if(!useForwardSlash) slash = "\\";
outFileName = "/var/run/vco/" + TargetResource.name;
guestFilePath = TargetDirectoryOnGuest + slash + TargetResource.name;
TargetResource.writeContentToFile(outFileName);

Copy File From vCO

Create the Copy file from vCO step by dragging and dropping a new Workflow element node on to the canvas between the Write Resource task and the workflow end node.  Search for “Copy file from vCO” to find the workflow which should be referenced in this step.  Double-click it to accept it on to the canvas.

Wire the inputs, attributes, and outputs in the following manner.

Inputs

Local Parameter	Source Parameter	Type
vmUsername	VMUsername	String
vmPassword	VMPassword	SecureString
Vm	VM	VC:VirtualMachine
vcoPath	outFileName	String
guestFilePath	guestFilePath	String
overwrite	overwrite	Boolean

Outputs

Local Parameter	Source Parameter	Type
Result	copyResult	boolean

The visual binding on the “Copy file from vCO” step should look as follows:

Figure 9. Visual binding for the "Copy file from vCO" step in the "Copy Resource To Guest" workflow

Decision

The decision in this workflow throws an error if necessary or continues to successful completion.  If the copyResult attribute has a value of true, then the operation completed successfully and we don’t throw an error.  If it is false, then we throw an error.

To create the decision step, drag a Decision node on to the canvas between the Copy file from vCO step and the workflow finish node.  Delete the new workflow completion node that has been added to the failure path of the new Decision node by clicking the failure path and hitting the delete key.

Drag a Throw exception node on top of the Decision node to add the Throw exception step to the failure path of the decision node.

Click the Decision tab within the Decision step.  Select the copyResult attribute as the decision variable.  Leave the drop-down condition set to “is true”

The decision tab of the Decision step should look as follows:

Figure 10. Decision tab of the Decision step of the "Copy Resource To Guest" workflow

Click the Throw exception step.  Within the Exception tab, bind the errorCode attribute to the exception binding.  This will cause the step to throw the error string contained within the errorCode variable.

Set Workflow Output

Create the Set Workflow Output step by dragging a Scriptable task node on to the canvase between the Decision step and the workflow end node.  Set the name of the step to “Set Workflow Output”.

The purpose of this step is simply to translate an attribute variable to an output variable.  We are going to take the guestFilePath attribute and copy its value to the output variable  called GuestFileName.

Wire the inputs and outputs as follows.

Inputs

Local Parameter	Source Parameter	Type
guestFilePath	guestFilePath	String

Outputs

Local Parameter	Source Parameter	Type
GuestFileName	GuestFileName	string

The visual binding for the Set Workflow Output step should look as follows:

Figure 11. Visual binding for the "Set Workflow Output" step of the "Copy Resource To Guest" workflow

Enter the following script into the Scripting tab:

GuestFileName = guestFilePath;

Save the workflow and test its execution in your environment by creating a resource element with some text content.  Execute the workflow and verify that the resource element chosen is copied as a file to the guest virtual machine.