CDConfig: Add cd_content for file templating

cmd/packer-sdc/internal/renderdocs/docs-partials/packer-plugin-sdk/multistep/commonsteps/CDConfig-not-required.mdx

@@ -44,6 +44,22 @@
     * hdiutil (normally found in macOS)
     * oscdimg (normally found in Windows as part of the Windows ADK)
 
+- `cd_content` (map[string]string) - Key/Values to add to the CD. The keys represent the paths, and the values
+  contents. It can be used alongside `cd_files`, which is useful to add large
+  files without loading them into memory. If any paths are specified by both,
+  the contents in `cd_content` will take precedence.
+
+  Usage example (HCL):
+
+  ```hcl
+  cd_files = ["vendor-data"]
+  cd_content = {
+    "meta-data" = jsonencode(local.instance_data)
+    "user-data" = templatefile("user-data", { packages = ["nginx"] })
+  }
+  cd_label = "cidata"
+  ```
+
 - `cd_label` (string) - CD Label
 
 <!-- End of code generated from the comments of the CDConfig struct in multistep/commonsteps/extra_iso_config.go; -->

multistep/commonsteps/extra_iso_config.go

@@ -65,7 +65,23 @@ type CDConfig struct {
 	//   * hdiutil (normally found in macOS)
 	//   * oscdimg (normally found in Windows as part of the Windows ADK)
 	CDFiles []string `mapstructure:"cd_files"`
-	CDLabel string   `mapstructure:"cd_label"`
+	// Key/Values to add to the CD. The keys represent the paths, and the values
+	// contents. It can be used alongside `cd_files`, which is useful to add large
+	// files without loading them into memory. If any paths are specified by both,
+	// the contents in `cd_content` will take precedence.
+	//
+	// Usage example (HCL):
+	//
+	// ```hcl
+	// cd_files = ["vendor-data"]
+	// cd_content = {
+	//   "meta-data" = jsonencode(local.instance_data)
+	//   "user-data" = templatefile("user-data", { packages = ["nginx"] })
+	// }
+	// cd_label = "cidata"
+	// ```
+	CDContent map[string]string `mapstructure:"cd_content"`
+	CDLabel   string            `mapstructure:"cd_label"`
 }
 
 func (c *CDConfig) Prepare(ctx *interpolate.Context) []error {

multistep/commonsteps/step_create_cdrom.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -22,16 +23,17 @@ type StepCreateCD struct {
 	// Files can be either files or directories. Any files provided here will
 	// be written to the root of the CD. Directories will be written to the
 	// root of the CD as well, but will retain their subdirectory structure.
-	Files []string
-	Label string
+	Files   []string
+	Content map[string]string
+	Label   string
 
 	CDPath string
 
 	rootFolder string
 }
 
 func (s *StepCreateCD) Run(ctx context.Context, state multistep.StateBag) multistep.StepAction {
-	if len(s.Files) == 0 {
+	if len(s.Files) == 0 && len(s.Content) == 0 {
 		log.Println("No CD files specified. CD disk will not be made.")
 		return multistep.ActionContinue
 	}
@@ -79,6 +81,15 @@ func (s *StepCreateCD) Run(ctx context.Context, state multistep.StateBag) multis
 		}
 	}
 
+	for path, content := range s.Content {
+		err = s.AddContent(rootFolder, path, content)
+		if err != nil {
+			state.Put("error",
+				fmt.Errorf("Error creating temporary file for CD: %s", err))
+			return multistep.ActionHalt
+		}
+	}
+
 	cmd, err := retrieveCDISOCreationCommand(s.Label, rootFolder, CDPath)
 	if err != nil {
 		state.Put("error", err)
@@ -291,3 +302,18 @@ func (s *StepCreateCD) AddFile(dst, src string) error {
 
 	return filepath.Walk(src, visit)
 }
+
+func (s *StepCreateCD) AddContent(dst, path, content string) error {
+	// Join Cleans the path so we can join it without path traversal issues.
+	dstPath := filepath.Join(dst, path)
+	dstDir := filepath.Dir(dstPath)
+	err := os.MkdirAll(dstDir, 0777)
+	if err != nil {
+		return fmt.Errorf("error creating new directory %s: %s", dstDir, err)
+	}
+	err = ioutil.WriteFile(dstPath, []byte(content), 0666)
+	if err != nil {
+		return fmt.Errorf("Error writing file %s on CD: %s", path, err)
+	}
+	return nil
+}

multistep/commonsteps/step_create_cdrom_test.go

@@ -92,17 +92,25 @@ func TestStepCreateCD(t *testing.T) {
 	}
 	defer os.RemoveAll(dir)
 
-	expected := map[string]string{
+	createFiles(t, dir, map[string]string{
 		"test folder/b/test1": "1",
 		"test folder/b/test2": "2",
 		"test folder 2/x":     "3",
 		"test_cd_roms.tmp":    "4",
 		"test cd files.tmp":   "5",
 		"Test-Test-Test5.tmp": "6",
+		"subfolder/meta-data": "subfolder/meta-data from files",
+		"subfolder/user-data": "subfolder/user-data from files",
+		"user-data":           "user-data from files",
+		"vendor-data":         "vendor-data from files",
+	})
+	step.Content = map[string]string{
+		"subfolder not created by files/test.tmp": "test",
+		"subfolder/meta-data":                     "subfolder/meta-data from content",
+		"user-data":                               "user-data from content",
 	}
 
-	createFiles(t, dir, expected)
-	files := []string{"test folder", "test folder 2/", "test_cd_roms.tmp", "test cd files.tmp", "Test-Test-Test5.tmp"}
+	files := []string{"test folder", "test folder 2/", "test_cd_roms.tmp", "test cd files.tmp", "Test-Test-Test5.tmp", "subfolder", "user-data", "vendor-data"}
 
 	step.Files = make([]string, len(files))
 	for i, fname := range files {
@@ -124,7 +132,19 @@ func TestStepCreateCD(t *testing.T) {
 		t.Fatalf("file not found: %s for %v", CD_path, step.Files)
 	}
 
-	checkFiles(t, step.rootFolder, expected)
+	checkFiles(t, step.rootFolder, map[string]string{
+		"test folder/b/test1":                     "1",
+		"test folder/b/test2":                     "2",
+		"test folder 2/x":                         "3",
+		"test_cd_roms.tmp":                        "4",
+		"test cd files.tmp":                       "5",
+		"Test-Test-Test5.tmp":                     "6",
+		"subfolder not created by files/test.tmp": "test",
+		"subfolder/meta-data":                     "subfolder/meta-data from content",
+		"subfolder/user-data":                     "subfolder/user-data from files",
+		"user-data":                               "user-data from content",
+		"vendor-data":                             "vendor-data from files",
+	})
 
 	step.Cleanup(state)
 
@@ -150,6 +170,9 @@ func TestStepCreateCD_missing(t *testing.T) {
 	defer os.RemoveAll(dir)
 
 	step.Files = []string{"missing file.tmp"}
+	step.Content = map[string]string{
+		"test_cd_roms.tmp": "should not be created",
+	}
 	if action := step.Run(context.Background(), state); action != multistep.ActionHalt {
 		t.Fatalf("bad action: %#v for %v", action, step.Files)
 	}