Interpolate boot_command when defined by user variable (#8640)

packer/core.go

@@ -397,12 +397,17 @@ func (c *Core) init() error {
 		allVariables[k] = v
 	}
 
+	// Regex to exclude any build function variable or template variable
+	// from interpolating earlier
+	// E.g.: {{ .HTTPIP }}  won't interpolate now
+	renderFilter := "{{(\\s|)\\.(.*?)(\\s|)}}"
+
 	for i := 0; i < 100; i++ {
 		shouldRetry = false
 		// First, loop over the variables in the template
 		for k, v := range allVariables {
 			// Interpolate the default
-			renderedV, err := interpolate.Render(v, ctx)
+			renderedV, err := interpolate.RenderRegex(v, ctx, renderFilter)
 			switch err.(type) {
 			case nil:
 				// We only get here if interpolation has succeeded, so something is

packer/core_test.go

@@ -143,6 +143,36 @@ func TestCoreBuild_env(t *testing.T) {
 	}
 }
 
+func TestCoreBuild_IgnoreTemplateVariables(t *testing.T) {
+	os.Setenv("PACKER_TEST_ENV", "test")
+	defer os.Setenv("PACKER_TEST_ENV", "")
+
+	config := TestCoreConfig(t)
+	testCoreTemplate(t, config, fixtureDir("build-ignore-template-variable.json"))
+	core := TestCore(t, config)
+
+	if core.variables["http_ip"] != "{{ .HTTPIP }}" {
+		t.Fatalf("bad: User variable http_ip={{ .HTTPIP }} should not be interpolated")
+	}
+
+	if core.variables["var"] != "test_{{ .PACKER_TEST_TEMP }}" {
+		t.Fatalf("bad: User variable var should be half interpolated to var=test_{{ .PACKER_TEST_TEMP }} but was var=%s", core.variables["var"])
+	}
+
+	if core.variables["array_var"] != "us-west-1,us-west-2" {
+		t.Fatalf("bad: User variable array_var should be \"us-west-1,us-west-2\" but was %s", core.variables["var"])
+	}
+
+	build, err := core.Build("test")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if _, err := build.Prepare(); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+}
+
 func TestCoreBuild_buildNameVar(t *testing.T) {
 	config := TestCoreConfig(t)
 	testCoreTemplate(t, config, fixtureDir("build-var-build-name.json"))

packer/test-fixtures/build-ignore-template-variable.json

@@ -0,0 +1,11 @@
+{
+    "variables": {
+        "var": "{{env `PACKER_TEST_ENV`}}_{{ .PACKER_TEST_TEMP }}",
+        "http_ip": "{{ .HTTPIP }}",
+        "array_var": "us-west-1,us-west-2"
+    },
+
+    "builders": [{
+        "type": "test"
+    }]
+}

template/interpolate/i.go

@@ -2,6 +2,9 @@ package interpolate
 
 import (
 	"bytes"
+	"github.com/google/uuid"
+	"regexp"
+	"strings"
 	"text/template"
 )
 
@@ -42,8 +45,44 @@ func NewContext() *Context {
 }
 
 // Render is shorthand for constructing an I and calling Render.
-func Render(v string, ctx *Context) (string, error) {
+func Render(v string, ctx *Context) (rendered string, err error) {
-	return (&I{Value: v}).Render(ctx)
+	// Keep interpolating until all variables are done
+	// Sometimes a variable can been inside another one
+	for {
+		rendered, err = (&I{Value: v}).Render(ctx)
+		if err != nil || rendered == v {
+			break
+		}
+		v = rendered
+	}
+	return
+}
+
+// Render is shorthand for constructing an I and calling Render.
+// Use regex to filter variables that are not supposed to be interpolated now
+func RenderRegex(v string, ctx *Context, regex string) (string, error) {
+	re := regexp.MustCompile(regex)
+	matches := re.FindAllStringSubmatch(v, -1)
+
+	// Replace variables to be excluded with a unique UUID
+	excluded := make(map[string]string)
+	for _, value := range matches {
+		id := uuid.New().String()
+		excluded[id] = value[0]
+		v = strings.ReplaceAll(v, value[0], id)
+	}
+
+	rendered, err := (&I{Value: v}).Render(ctx)
+	if err != nil {
+		return rendered, err
+	}
+
+	// Replace back by the UUID the previously excluded values
+	for id, value := range excluded {
+		rendered = strings.ReplaceAll(rendered, id, value)
+	}
+
+	return rendered, nil
 }
 
 // Validate is shorthand for constructing an I and calling Validate.