Post-Processor: added vagrantfile_template_content option to allow for dynamic Vagrantfile content

[VishnuJin]

As specified in the issue, users can now use templatefile function for dynamic content in Vagrantfile template

Example:
A vagrant template file

Vagrant.configure("2") do |config|
  config.ssh.private_key_path = ${my_ssh_key}
  config.ssh.forward_agent = true
end

A packer file with vagrant post processor

locals {
   vagrantfile = templatefile("vagrantfile.pkrtpl.hcl", { 
      my_ssh_key = "~/.ssh/rsa"
    })
 }
 ....
 post-processor "vagrant" {
    vagrantfile_template_content = local.vagrantfile
 } 

Resulting Vagrantfile inside Box file

# The contents below were provided by the Packer Vagrant post-processor

Vagrant.configure("2") do |config|
	config.vm.provider :docker do |docker, override|
		docker.image = "sha256:47045c52cefdfd009eb4cfb69dc7c2ac3b2af7808abb218164a7a2264847c939"
	end
end


# The contents below (if any) are custom contents provided by the
# Packer template during image build.
Vagrant.configure("2") do |config|
  config.ssh.private_key_path = ~/.ssh/rsa
  config.ssh.forward_agent = true
end

Closes #104

[nywilken]

Hi there apologies for the delayed review here. Our focus has been on Packer itself trying to resolve issues with plugin loading. Looking at the changes and reference issue I can understand the need for this feature.

However, I am a little unclear on the expected usage of vagrantfile_template and vagrantfile_template_content. Please take a look at my suggested changes and questions.

If you're no longer interested in making the change I do understand given the time to review. I'll label the PR and await your response.

[nywilken]

I believe this condition might be nested in a conflicting if statement.

// lets default to using VagrantTemplateContent
templateContent := config.VagrantfileTemplateContent
if templateContent == "" && config.VagrantfileTemplate != "" {
	ui.Message(fmt.Sprintf("Using custom Vagrantfile: %s", config.VagrantfileTemplate))
	customBytes, err := ioutil.ReadFile(config.VagrantfileTemplate)
	if err != nil {
		return nil, false, err
	}
	templateContent = string(customBytes)
}
	
if templateContent != "" {
       customVagrantfile, err = interpolate.Render(templateContent, &config.ctx)
	if err != nil {
		return nil, false, err
	}
}

[VishnuJin]

@nywilken could you please see the below comment #112 (comment) and let me know if this is still needs to be changed !!

[nywilken]

I am of the understanding that you would want to specify just the content with no filepath needed. Is that not the case?

If they are mutually exclusive I would rewrite the logic to be as follows:

Suggested change

	if c.VagrantfileTemplateContent != "" && c.VagrantfileTemplate == "" {
	errs = packersdk.MultiErrorAppend(errs, fmt.Errorf(
	"'vagrantfile_template' should be provided to use 'vagrantfile_template_content'"))
	}
	if c.VagrantfileTemplateContent != "" && c.VagrantfileTemplate != "" {
	errs = packersdk.MultiErrorAppend(errs, fmt.Errorf(
	"'vagrantfile_template' can not be used with 'vagrantfile_template_content'"))
	}

[VishnuJin]

@nywilken if you see the example here these are Not Exclusive we are trying to load the value for the variable my_ssh_key in the vagrant_template

[nywilken]

Hi @VishnuJin just want to follow up to see if you would like to continue with this change. Please let me know if you have time to continue pushing it forward and if you have any questions about the provided feedback.

Thank you for your contributions to this plugin.