post-processor: add vagrantfile_content option

.web-docs/components/post-processor/vagrant/README.md

@@ -105,6 +105,12 @@ more details about certain options in following sections.
   creation of the Vagrantfile at some previous point in the build.
   Defaults to `false`.
 
+- `vagrantfile_content` (string) - Content of the custom Vagrantfile that is
+  packaged with the box. This option is intended to be used with
+  [`templatefile`](https://developer.hashicorp.com/packer/docs/templates/hcl_templates/functions/file/templatefile)
+  function in HCL templates, instead of `vagrantfile_template`.
+  `vagrantfile_content` and `vagrantfile_template` can't be set both at the same time.
+
 ## Using together with the Artifice post-processor
 
 Sometimes you may want to run several builds in a pipeline rather than running

docs/post-processors/vagrant.mdx

@@ -121,6 +121,12 @@ more details about certain options in following sections.
   creation of the Vagrantfile at some previous point in the build.
   Defaults to `false`.
 
+- `vagrantfile_content` (string) - Content of the custom Vagrantfile that is
+  packaged with the box. This option is intended to be used with
+  [`templatefile`](https://developer.hashicorp.com/packer/docs/templates/hcl_templates/functions/file/templatefile)
+  function in HCL templates, instead of `vagrantfile_template`.
+  `vagrantfile_content` and `vagrantfile_template` can't be set both at the same time.
+
 ## Using together with the Artifice post-processor
 
 Sometimes you may want to run several builds in a pipeline rather than running

post-processor/vagrant/post-processor.go

@@ -74,6 +74,7 @@ type Config struct {
 	Include                      []string `mapstructure:"include"`
 	OutputPath                   string   `mapstructure:"output"`
 	Override                     map[string]interface{}
+	VagrantfileContent           string `mapstructure:"vagrantfile_content"`
 	VagrantfileTemplate          string `mapstructure:"vagrantfile_template"`
 	VagrantfileTemplateGenerated bool   `mapstructure:"vagrantfile_template_generated"`
 	ProviderOverride             string `mapstructure:"provider_override"`
@@ -188,7 +189,9 @@ func (p *PostProcessor) PostProcessProvider(name string, provider Provider, ui p
 
 	// Write our Vagrantfile
 	var customVagrantfile string
-	if config.VagrantfileTemplate != "" {
+	if config.VagrantfileContent != "" {
+		customVagrantfile = config.VagrantfileContent
+	} else if config.VagrantfileTemplate != "" {
 		ui.Message(fmt.Sprintf("Using custom Vagrantfile: %s", config.VagrantfileTemplate))
 		customBytes, err := ioutil.ReadFile(config.VagrantfileTemplate)
 		if err != nil {
@@ -292,6 +295,11 @@ func (p *PostProcessor) configureSingle(c *Config, raws ...interface{}) error {
 	}
 
 	var errs *packersdk.MultiError
+	if c.VagrantfileContent != "" && c.VagrantfileTemplate != "" {
+		errs = packersdk.MultiErrorAppend(errs, fmt.Errorf(
+			"You may either set vagrantfile_content or vagrantfile_template but not both"))
+	}
+
 	if c.VagrantfileTemplate != "" && c.VagrantfileTemplateGenerated == false {
 		_, err := os.Stat(c.VagrantfileTemplate)
 		if err != nil {

post-processor/vagrant/post-processor_test.go

@@ -202,6 +202,22 @@ func TestPostProcessorPrepare_vagrantfileTemplateExists(t *testing.T) {
 	}
 }
 
+func TestPostProcessorPrepare_vagrantfileContent(t *testing.T) {
+	c := testConfig()
+	c["vagrantfile_content"] = "Vagrant.configure('2') do |config|\nend\n"
+
+	var p PostProcessor
+
+	if err := p.Configure(c); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	c["vagrantfile_template"] = "Vagrantfile"
+	if err := p.Configure(c); err == nil {
+		t.Fatal("expected error since vagrantfile_content and vagrantfile_template are both set")
+	}
+}
+
 func TestPostProcessorPrepare_ProviderOverrideExists(t *testing.T) {
 	c := testConfig()
 	c["provider_override"] = "foo"