diff --git a/builder/azure/chroot/builder_test.go b/builder/azure/chroot/builder_test.go
index 40156bf1f..dd40f7737 100644
--- a/builder/azure/chroot/builder_test.go
+++ b/builder/azure/chroot/builder_test.go
@@ -1,58 +1,53 @@
 package chroot
 
 import (
-	"reflect"
-	"regexp"
 	"testing"
 
-	"github.com/hashicorp/packer/packer"
+	"github.com/Azure/azure-sdk-for-go/profiles/latest/compute/mgmt/compute"
 )
 
-func TestBuilder_Prepare_DiskAsInput(t *testing.T) {
-	b := Builder{}
-	_, err := b.Prepare(map[string]interface{}{
-		"source": "/subscriptions/28279221-ccbe-40f0-b70b-4d78ab822e09/resourceGroups/testrg/providers/Microsoft.Compute/disks/diskname",
-	})
-
-	if err != nil {
-		// make sure there is no error about the source field
-		errs, ok := err.(*packer.MultiError)
-		if !ok {
-			t.Error("Expected the returned error to be of type packer.MultiError")
-		}
-		for _, err := range errs.Errors {
-			if matched, _ := regexp.MatchString(`(^|\W)source\W`, err.Error()); matched {
-				t.Errorf("Did not expect an error about the 'source' field, but found %q", err)
-			}
-		}
-	}
-}
-
 func TestBuilder_Prepare(t *testing.T) {
 	type config map[string]interface{}
-	
+	type regexMatchers map[string]string // map of regex : error message
+
 	tests := []struct {
 		name     string
 		config   config
-		want     []string
 		validate func(Config)
 		wantErr  bool
 	}{
 		{
-			name: "HappyPath",
+			name: "HappyPathFromPlatformImage",
 			config: config{
 				"client_id":         "123",
 				"client_secret":     "456",
 				"subscription_id":   "789",
-				"resource_group":    "rgname",
 				"image_resource_id": "/subscriptions/789/resourceGroups/otherrgname/providers/Microsoft.Compute/images/MyDebianOSImage-{{timestamp}}",
 				"source":            "credativ:Debian:9:latest",
 			},
-			wantErr: false,
-			validate: func(c Config){
-				if(c.OSDiskSizeGB!=0){
-					t.Fatalf("Expected OSDiskSizeGB to be 0, was %+v", c.OSDiskSizeGB)
+			validate: func(c Config) {
+				if c.OSDiskSizeGB != 0 {
+					t.Errorf("Expected OSDiskSizeGB to be 0, was %+v", c.OSDiskSizeGB)
 				}
+				if c.MountPartition != "1" {
+					t.Errorf("Expected MountPartition to be %s, but found %s", "1", c.MountPartition)
+				}
+				if c.OSDiskStorageAccountType != string(compute.PremiumLRS) {
+					t.Errorf("Expected OSDiskStorageAccountType to be %s, but found %s", string(compute.PremiumLRS), c.OSDiskStorageAccountType)
+				}
+				if c.OSDiskCacheType != string(compute.CachingTypesReadOnly) {
+					t.Errorf("Expected OSDiskCacheType to be %s, but found %s", string(compute.CachingTypesReadOnly), c.OSDiskCacheType)
+				}
+				if c.ImageHyperVGeneration != string(compute.V1) {
+					t.Errorf("Expected ImageHyperVGeneration to be %s, but found %s", string(compute.V1), c.ImageHyperVGeneration)
+				}
+			},
+		},
+		{
+			name: "HappyPathFromPlatformImage",
+			config: config{
+				"image_resource_id": "/subscriptions/789/resourceGroups/otherrgname/providers/Microsoft.Compute/images/MyDebianOSImage-{{timestamp}}",
+				"source":            "/subscriptions/789/resourceGroups/testrg/providers/Microsoft.Compute/disks/diskname",
 			},
 		},
 	}
@@ -60,13 +55,15 @@ func TestBuilder_Prepare(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			b := &Builder{}
 
-			got, err := b.Prepare(tt.config)
+			_, err := b.Prepare(tt.config)
+
 			if (err != nil) != tt.wantErr {
 				t.Errorf("Builder.Prepare() error = %v, wantErr %v", err, tt.wantErr)
 				return
 			}
-			if !reflect.DeepEqual(got, tt.want) {
-				t.Errorf("Builder.Prepare() = %v, want %v", got, tt.want)
+
+			if tt.validate != nil {
+				tt.validate(b.config)
 			}
 		})
 	}
diff --git a/examples/azure/debian-chroot.json b/examples/azure/debian-chroot.json
index 4b29632b1..00909a55f 100644
--- a/examples/azure/debian-chroot.json
+++ b/examples/azure/debian-chroot.json
@@ -2,7 +2,8 @@
   "variables": {
     "client_id": "{{env `ARM_CLIENT_ID`}}",
     "client_secret": "{{env `ARM_CLIENT_SECRET`}}",
-    "subscription_id": "{{env `ARM_SUBSCRIPTION_ID`}}"
+    "subscription_id": "{{env `ARM_SUBSCRIPTION_ID`}}",
+    "resource_group": "{{env `ARM_IMAGE_RESOURCEGROUP_ID`}}"
   },
   "builders": [{
     "type": "azure-chroot",
@@ -23,4 +24,4 @@
     "inline_shebang": "/bin/sh -x",
     "type": "shell"
   }]
-}
+}
\ No newline at end of file
diff --git a/website/source/docs/builders/azure-chroot.html.md.erb b/website/source/docs/builders/azure-chroot.html.md.erb
index 71b488deb..7244671a7 100644
--- a/website/source/docs/builders/azure-chroot.html.md.erb
+++ b/website/source/docs/builders/azure-chroot.html.md.erb
@@ -104,18 +104,19 @@ mounts `/prod` and `/dev`:
 ## Example
 Here is an example that creates a Debian image with updated packages. Specify
 all environment variables (`ARM_CLIENT_ID`, `ARM_CLIENT_SECRET`, 
-`ARM_SUBSCRIPTION_ID`) to use a service principal, specify only `ARM_SUBSCRIPTION_ID`
-to use interactive login or leave them empty to use the system-assigned identity
-of the VM you run Packer on.
+`ARM_SUBSCRIPTION_ID`) to use a service principal.
 The identity you choose should have permission to create disks and images and also
 to update your VM.
+Set the `ARM_IMAGE_RESOURCEGROUP_ID` variable to an existing resource group in the
+subscription where the resulting image will be created.
 
 ``` json
 {
   "variables": {
     "client_id": "{{env `ARM_CLIENT_ID`}}",
     "client_secret": "{{env `ARM_CLIENT_SECRET`}}",
-    "subscription_id": "{{env `ARM_SUBSCRIPTION_ID`}}"
+    "subscription_id": "{{env `ARM_SUBSCRIPTION_ID`}}",
+    "resource_group": "{{env `ARM_IMAGE_RESOURCEGROUP_ID`}}"
   },
   "builders": [{
     "type": "azure-chroot",