Merge pull request #6088 from adongy/master

Expose more source ami data in the template

builder/amazon/common/interpolate_build_info.go

@@ -1,6 +1,36 @@
 package common
 
+import (
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/hashicorp/packer/helper/multistep"
+)
+
 type BuildInfoTemplate struct {
-	SourceAMI   string
 	BuildRegion   string
+	SourceAMI     string
+	SourceAMIName string
+	SourceAMITags map[string]string
+}
+
+func extractBuildInfo(region string, state multistep.StateBag) *BuildInfoTemplate {
+	rawSourceAMI, hasSourceAMI := state.GetOk("source_image")
+	if !hasSourceAMI {
+		return &BuildInfoTemplate{
+			BuildRegion: region,
+		}
+	}
+
+	sourceAMI := rawSourceAMI.(*ec2.Image)
+	sourceAMITags := make(map[string]string, len(sourceAMI.Tags))
+	for _, tag := range sourceAMI.Tags {
+		sourceAMITags[aws.StringValue(tag.Key)] = aws.StringValue(tag.Value)
+	}
+
+	return &BuildInfoTemplate{
+		BuildRegion:   region,
+		SourceAMI:     aws.StringValue(sourceAMI.ImageId),
+		SourceAMIName: aws.StringValue(sourceAMI.Name),
+		SourceAMITags: sourceAMITags,
+	}
 }

builder/amazon/common/interpolate_build_info_test.go

@@ -0,0 +1,63 @@
+package common
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/hashicorp/packer/helper/multistep"
+)
+
+func testImage() *ec2.Image {
+	return &ec2.Image{
+		ImageId: aws.String("ami-abcd1234"),
+		Name:    aws.String("ami_test_name"),
+		Tags: []*ec2.Tag{
+			{
+				Key:   aws.String("key-1"),
+				Value: aws.String("value-1"),
+			},
+			{
+				Key:   aws.String("key-2"),
+				Value: aws.String("value-2"),
+			},
+		},
+	}
+}
+
+func testState() multistep.StateBag {
+	state := new(multistep.BasicStateBag)
+	return state
+}
+
+func TestInterpolateBuildInfo_extractBuildInfo_noSourceImage(t *testing.T) {
+	state := testState()
+	buildInfo := extractBuildInfo("foo", state)
+
+	expected := BuildInfoTemplate{
+		BuildRegion: "foo",
+	}
+	if !reflect.DeepEqual(*buildInfo, expected) {
+		t.Fatalf("Unexpected BuildInfoTemplate: expected %#v got %#v\n", expected, *buildInfo)
+	}
+}
+
+func TestInterpolateBuildInfo_extractBuildInfo_withSourceImage(t *testing.T) {
+	state := testState()
+	state.Put("source_image", testImage())
+	buildInfo := extractBuildInfo("foo", state)
+
+	expected := BuildInfoTemplate{
+		BuildRegion:   "foo",
+		SourceAMI:     "ami-abcd1234",
+		SourceAMIName: "ami_test_name",
+		SourceAMITags: map[string]string{
+			"key-1": "value-1",
+			"key-2": "value-2",
+		},
+	}
+	if !reflect.DeepEqual(*buildInfo, expected) {
+		t.Fatalf("Unexpected BuildInfoTemplate: expected %#v got %#v\n", expected, *buildInfo)
+	}
+}

builder/amazon/common/step_create_tags.go

@@ -26,13 +26,6 @@ func (s *StepCreateTags) Run(_ context.Context, state multistep.StateBag) multis
 	ui := state.Get("ui").(packer.Ui)
 	amis := state.Get("amis").(map[string]string)
 
-	var sourceAMI string
-	if rawSourceAMI, hasSourceAMI := state.GetOk("source_image"); hasSourceAMI {
-		sourceAMI = *rawSourceAMI.(*ec2.Image).ImageId
-	} else {
-		sourceAMI = ""
-	}
-
 	if !s.Tags.IsSet() && !s.SnapshotTags.IsSet() {
 		return multistep.ActionContinue
 	}
@@ -79,7 +72,7 @@ func (s *StepCreateTags) Run(_ context.Context, state multistep.StateBag) multis
 
 		// Convert tags to ec2.Tag format
 		ui.Say("Creating AMI tags")
-		amiTags, err := s.Tags.EC2Tags(s.Ctx, *ec2conn.Config.Region, sourceAMI)
+		amiTags, err := s.Tags.EC2Tags(s.Ctx, *ec2conn.Config.Region, state)
 		if err != nil {
 			state.Put("error", err)
 			ui.Error(err.Error())
@@ -88,7 +81,7 @@ func (s *StepCreateTags) Run(_ context.Context, state multistep.StateBag) multis
 		amiTags.Report(ui)
 
 		ui.Say("Creating snapshot tags")
-		snapshotTags, err := s.SnapshotTags.EC2Tags(s.Ctx, *ec2conn.Config.Region, sourceAMI)
+		snapshotTags, err := s.SnapshotTags.EC2Tags(s.Ctx, *ec2conn.Config.Region, state)
 		if err != nil {
 			state.Put("error", err)
 			ui.Error(err.Error())

builder/amazon/common/step_modify_ami_attributes.go

@@ -27,13 +27,6 @@ func (s *StepModifyAMIAttributes) Run(_ context.Context, state multistep.StateBa
 	session := state.Get("awsSession").(*session.Session)
 	ui := state.Get("ui").(packer.Ui)
 	amis := state.Get("amis").(map[string]string)
-
-	var sourceAMI string
-	if rawSourceAMI, hasSourceAMI := state.GetOk("source_image"); hasSourceAMI {
-		sourceAMI = *rawSourceAMI.(*ec2.Image).ImageId
-	} else {
-		sourceAMI = ""
-	}
 	snapshots := state.Get("snapshots").(map[string][]string)
 
 	// Determine if there is any work to do.
@@ -50,10 +43,7 @@ func (s *StepModifyAMIAttributes) Run(_ context.Context, state multistep.StateBa
 	}
 
 	var err error
-	s.Ctx.Data = &BuildInfoTemplate{
+	s.Ctx.Data = extractBuildInfo(*ec2conn.Config.Region, state)
-		SourceAMI:   sourceAMI,
-		BuildRegion: *ec2conn.Config.Region,
-	}
 	s.Description, err = interpolate.Render(s.Description, &s.Ctx)
 	if err != nil {
 		err = fmt.Errorf("Error interpolating AMI description: %s", err)

builder/amazon/common/step_run_source_instance.go

@@ -88,7 +88,7 @@ func (s *StepRunSourceInstance) Run(_ context.Context, state multistep.StateBag)
 		s.Tags["Name"] = "Packer Builder"
 	}
 
-	ec2Tags, err := s.Tags.EC2Tags(s.Ctx, *ec2conn.Config.Region, s.SourceAMI)
+	ec2Tags, err := s.Tags.EC2Tags(s.Ctx, *ec2conn.Config.Region, state)
 	if err != nil {
 		err := fmt.Errorf("Error tagging source instance: %s", err)
 		state.Put("error", err)
@@ -96,7 +96,7 @@ func (s *StepRunSourceInstance) Run(_ context.Context, state multistep.StateBag)
 		return multistep.ActionHalt
 	}
 
-	volTags, err := s.VolumeTags.EC2Tags(s.Ctx, *ec2conn.Config.Region, s.SourceAMI)
+	volTags, err := s.VolumeTags.EC2Tags(s.Ctx, *ec2conn.Config.Region, state)
 	if err != nil {
 		err := fmt.Errorf("Error tagging volumes: %s", err)
 		state.Put("error", err)
@@ -259,7 +259,7 @@ func (s *StepRunSourceInstance) Run(_ context.Context, state multistep.StateBag)
 		if len(volumeIds) > 0 && s.VolumeTags.IsSet() {
 			ui.Say("Adding tags to source EBS Volumes")
 
-			volumeTags, err := s.VolumeTags.EC2Tags(s.Ctx, *ec2conn.Config.Region, s.SourceAMI)
+			volumeTags, err := s.VolumeTags.EC2Tags(s.Ctx, *ec2conn.Config.Region, state)
 			if err != nil {
 				err := fmt.Errorf("Error tagging source EBS Volumes on %s: %s", *instance.InstanceId, err)
 				state.Put("error", err)

builder/amazon/common/step_run_spot_instance.go

@@ -143,7 +143,7 @@ func (s *StepRunSpotInstance) Run(_ context.Context, state multistep.StateBag) m
 		s.Tags["Name"] = "Packer Builder"
 	}
 
-	ec2Tags, err := s.Tags.EC2Tags(s.Ctx, *ec2conn.Config.Region, s.SourceAMI)
+	ec2Tags, err := s.Tags.EC2Tags(s.Ctx, *ec2conn.Config.Region, state)
 	if err != nil {
 		err := fmt.Errorf("Error tagging source instance: %s", err)
 		state.Put("error", err)
@@ -287,7 +287,7 @@ func (s *StepRunSpotInstance) Run(_ context.Context, state multistep.StateBag) m
 	if len(volumeIds) > 0 && s.VolumeTags.IsSet() {
 		ui.Say("Adding tags to source EBS Volumes")
 
-		volumeTags, err := s.VolumeTags.EC2Tags(s.Ctx, *ec2conn.Config.Region, s.SourceAMI)
+		volumeTags, err := s.VolumeTags.EC2Tags(s.Ctx, *ec2conn.Config.Region, state)
 		if err != nil {
 			err := fmt.Errorf("Error tagging source EBS Volumes on %s: %s", *instance.InstanceId, err)
 			state.Put("error", err)

builder/amazon/common/tags.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/hashicorp/packer/helper/multistep"
 	"github.com/hashicorp/packer/packer"
 	"github.com/hashicorp/packer/template/interpolate"
 )
@@ -23,12 +24,10 @@ func (t TagMap) IsSet() bool {
 	return len(t) > 0
 }
 
-func (t TagMap) EC2Tags(ctx interpolate.Context, region, sourceAMIID string) (EC2Tags, error) {
+func (t TagMap) EC2Tags(ctx interpolate.Context, region string, state multistep.StateBag) (EC2Tags, error) {
 	var ec2Tags []*ec2.Tag
-	ctx.Data = &BuildInfoTemplate{
+	ctx.Data = extractBuildInfo(region, state)
-		SourceAMI:   sourceAMIID,
+
-		BuildRegion: region,
-	}
 	for key, value := range t {
 		interpolatedKey, err := interpolate.Render(key, &ctx)
 		if err != nil {

builder/amazon/ebsvolume/step_tag_ebs_volumes.go

@@ -18,7 +18,6 @@ type stepTagEBSVolumes struct {
 func (s *stepTagEBSVolumes) Run(_ context.Context, state multistep.StateBag) multistep.StepAction {
 	ec2conn := state.Get("ec2").(*ec2.EC2)
 	instance := state.Get("instance").(*ec2.Instance)
-	sourceAMI := state.Get("source_image").(*ec2.Image)
 	ui := state.Get("ui").(packer.Ui)
 
 	volumes := make(EbsVolumes)
@@ -43,7 +42,7 @@ func (s *stepTagEBSVolumes) Run(_ context.Context, state multistep.StateBag) mul
 				continue
 			}
 
-			tags, err := mapping.Tags.EC2Tags(s.Ctx, *ec2conn.Config.Region, *sourceAMI.ImageId)
+			tags, err := mapping.Tags.EC2Tags(s.Ctx, *ec2conn.Config.Region, state)
 			if err != nil {
 				err := fmt.Errorf("Error tagging device %s with %s", mapping.DeviceName, err)
 				state.Put("error", err)

website/source/docs/builders/amazon-chroot.html.md

@@ -77,10 +77,8 @@ each category, the available configuration keys are alphabetized.
 
 -   `ami_description` (string) - The description to set for the
     resulting AMI(s). By default this description is empty. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with name of the region where this
-    is built.
 
 -   `ami_groups` (array of strings) - A list of groups that have access to
     launch the resulting AMI(s). By default no groups have permission to launch
@@ -251,10 +249,8 @@ each category, the available configuration keys are alphabetized.
 
 -   `snapshot_tags` (object of key/value strings) - Tags to apply to snapshot.
     They will override AMI tags if already applied to snapshot. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with name of the region where this
-    is built.
 
 -   `snapshot_groups` (array of strings) - A list of groups that have access to
     create volumes from the snapshot(s). By default no groups have permission to create
@@ -307,10 +303,8 @@ each category, the available configuration keys are alphabetized.
     Default `false`.
 
 -   `tags` (object of key/value strings) - Tags applied to the AMI. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with name of the region where this
-    is built.
 
 ## Basic Example
 
@@ -432,3 +426,12 @@ provisioning commands to install the os and bootloader.
   ]
 }
 ```
+
+## Build template data
+
+The available variables are:
+
+- `BuildRegion` - The region (for example `eu-central-1`) where Packer is building the AMI.
+- `SourceAMI` - The source AMI ID (for example `ami-a2412fcd`) used to build the AMI.
+- `SourceAMIName` - The source AMI Name (for example `ubuntu/images/ebs-ssd/ubuntu-xenial-16.04-amd64-server-20180306`) used to build the AMI.
+- `SourceAMITags` - The source AMI Tags, as a `map[string]string` object.

website/source/docs/builders/amazon-ebs.html.md

@@ -114,9 +114,8 @@ builder.
 
 -   `ami_description` (string) - The description to set for the
     resulting AMI(s). By default this description is empty. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `ami_groups` (array of strings) - A list of groups that have access to
     launch the resulting AMI(s). By default no groups have permission to launch
@@ -221,16 +220,14 @@ builder.
 -   `run_tags` (object of key/value strings) - Tags to apply to the instance
     that is *launched* to create the AMI. These tags are *not* applied to the
     resulting AMI unless they're duplicated in `tags`. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `run_volume_tags` (object of key/value strings) - Tags to apply to the volumes
     that are *launched* to create the AMI. These tags are *not* applied to the
     resulting AMI unless they're duplicated in `tags`. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `security_group_id` (string) - The ID (*not* the name) of the security group
     to assign to the instance. By default this is not set and Packer will
@@ -264,9 +261,8 @@ builder.
 
 -   `snapshot_tags` (object of key/value strings) - Tags to apply to snapshot.
     They will override AMI tags if already applied to snapshot. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `source_ami_filter` (object) - Filters used to populate the `source_ami` field.
     Example:
@@ -361,9 +357,8 @@ builder.
 
 -   `tags` (object of key/value strings) - Tags applied to the AMI and
     relevant snapshots. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `temporary_key_pair_name` (string) - The name of the temporary key pair
     to generate. By default, Packer generates a name that looks like
@@ -462,6 +457,15 @@ configuration of `launch_block_device_mappings` will expand the root volume
 }
 ```
 
+## Build template data
+
+The available variables are:
+
+- `BuildRegion` - The region (for example `eu-central-1`) where Packer is building the AMI.
+- `SourceAMI` - The source AMI ID (for example `ami-a2412fcd`) used to build the AMI.
+- `SourceAMIName` - The source AMI Name (for example `ubuntu/images/ebs-ssd/ubuntu-xenial-16.04-amd64-server-20180306`) used to build the AMI.
+- `SourceAMITags` - The source AMI Tags, as a `map[string]string` object.
+
 ## Tag Example
 
 Here is an example using the optional AMI tags. This will add the tags
@@ -481,7 +485,9 @@ images exist when this template is run:
   "ami_name": "packer-quick-start {{timestamp}}",
   "tags": {
     "OS_Version": "Ubuntu",
-    "Release": "Latest"
+    "Release": "Latest",
+    "Base_AMI_Name": "{{ .SourceAMIName }}",
+    "Extra": "{{ .SourceAMITags.TagName }}"
   }
 }
 ```

website/source/docs/builders/amazon-ebssurrogate.html.md

@@ -107,9 +107,8 @@ builder.
 
 -   `ami_description` (string) - The description to set for the
     resulting AMI(s). By default this description is empty. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `ami_groups` (array of strings) - A list of groups that have access to
     launch the resulting AMI(s). By default no groups have permission to launch
@@ -214,16 +213,14 @@ builder.
 -   `run_tags` (object of key/value strings) - Tags to apply to the instance
     that is *launched* to create the AMI. These tags are *not* applied to the
     resulting AMI unless they're duplicated in `tags`. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `run_volume_tags` (object of key/value strings) - Tags to apply to the volumes
     that are *launched* to create the AMI. These tags are *not* applied to the
     resulting AMI unless they're duplicated in `tags`. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `security_group_id` (string) - The ID (*not* the name) of the security group
     to assign to the instance. By default this is not set and Packer will
@@ -257,9 +254,8 @@ builder.
 
 -   `snapshot_tags` (object of key/value strings) - Tags to apply to snapshot.
     They will override AMI tags if already applied to snapshot. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `source_ami_filter` (object) - Filters used to populate the `source_ami` field.
     Example:
@@ -354,9 +350,8 @@ builder.
 
 -   `tags` (object of key/value strings) - Tags applied to the AMI and
     relevant snapshots. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `temporary_key_pair_name` (string) - The name of the temporary keypair
     to generate. By default, Packer generates a name with a UUID.
@@ -426,6 +421,16 @@ with the `-debug` flag. In debug mode, the Amazon builder will save the private
 key in the current directory and will output the DNS or IP information as well.
 You can use this information to access the instance as it is running.
 
+## Build template data
+
+The available variables are:
+
+- `BuildRegion` - The region (for example `eu-central-1`) where Packer is building the AMI.
+- `SourceAMI` - The source AMI ID (for example `ami-a2412fcd`) used to build the AMI.
+- `SourceAMIName` - The source AMI Name (for example `ubuntu/images/ebs-ssd/ubuntu-xenial-16.04-amd64-server-20180306`) used to build the AMI.
+- `SourceAMITags` - The source AMI Tags, as a `map[string]string` object.
+
+
 -> **Note:** Packer uses pre-built AMIs as the source for building images.
 These source AMIs may include volumes that are not flagged to be destroyed on
 termination of the instance building the new image. In addition to those volumes

website/source/docs/builders/amazon-ebsvolume.html.md

@@ -86,10 +86,9 @@ builder.
         volumes, `io1` for Provisioned IOPS (SSD) volumes, and `standard` for Magnetic
         volumes
     -   `tags` (map) - Tags to apply to the volume. These are retained after the
-        builder completes. This is a \[template engine\]
+        builder completes. This is a
-        (/docs/templates/engine.html) where the `SourceAMI`
+        [template engine](/docs/templates/engine.html),
-        variable is replaced with the source AMI ID and `BuildRegion` variable
+        see [Build template data](#build-template-data) for more information.
-        is replaced with the value of `region`.
 
 -   `associate_public_ip_address` (boolean) - If using a non-default VPC, public
     IP addresses are not provided by default. If this is toggled, your new
@@ -126,9 +125,8 @@ builder.
 -   `run_tags` (object of key/value strings) - Tags to apply to the instance
     that is *launched* to create the AMI. These tags are *not* applied to the
     resulting AMI unless they're duplicated in `tags`. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `security_group_id` (string) - The ID (*not* the name) of the security group
     to assign to the instance. By default this is not set and Packer will
@@ -328,6 +326,15 @@ with the `-debug` flag. In debug mode, the Amazon builder will save the private
 key in the current directory and will output the DNS or IP information as well.
 You can use this information to access the instance as it is running.
 
+## Build template data
+
+The available variables are:
+
+- `BuildRegion` - The region (for example `eu-central-1`) where Packer is building the AMI.
+- `SourceAMI` - The source AMI ID (for example `ami-a2412fcd`) used to build the AMI.
+- `SourceAMIName` - The source AMI Name (for example `ubuntu/images/ebs-ssd/ubuntu-xenial-16.04-amd64-server-20180306`) used to build the AMI.
+- `SourceAMITags` - The source AMI Tags, as a `map[string]string` object.
+
 -> **Note:** Packer uses pre-built AMIs as the source for building images.
 These source AMIs may include volumes that are not flagged to be destroyed on
 termination of the instance building the new image. In addition to those volumes

website/source/docs/builders/amazon-instance.html.md

@@ -136,9 +136,8 @@ builder.
 
 -   `ami_description` (string) - The description to set for the
     resulting AMI(s). By default this description is empty. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `ami_groups` (array of strings) - A list of groups that have access to
     launch the resulting AMI(s). By default no groups have permission to launch
@@ -236,9 +235,8 @@ builder.
 -   `run_tags` (object of key/value strings) - Tags to apply to the instance
     that is *launched* to create the AMI. These tags are *not* applied to the
     resulting AMI unless they're duplicated in `tags`. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `security_group_id` (string) - The ID (*not* the name) of the security group
     to assign to the instance. By default this is not set and Packer will
@@ -361,9 +359,8 @@ builder.
     required if you are using an non-default VPC.
 
 -   `tags` (object of key/value strings) - Tags applied to the AMI. This is a
-    [template engine](/docs/templates/engine.html)
+    [template engine](/docs/templates/engine.html),
-    where the `SourceAMI` variable is replaced with the source AMI ID and
+    see [Build template data](#build-template-data) for more information.
-    `BuildRegion` variable is replaced with the value of `region`.
 
 -   `temporary_key_pair_name` (string) - The name of the temporary key pair
     to generate. By default, Packer generates a name that looks like
@@ -425,6 +422,15 @@ with the `-debug` flag. In debug mode, the Amazon builder will save the private
 key in the current directory and will output the DNS or IP information as well.
 You can use this information to access the instance as it is running.
 
+## Build template data
+
+The available variables are:
+
+- `BuildRegion` - The region (for example `eu-central-1`) where Packer is building the AMI.
+- `SourceAMI` - The source AMI ID (for example `ami-a2412fcd`) used to build the AMI.
+- `SourceAMIName` - The source AMI Name (for example `ubuntu/images/ebs-ssd/ubuntu-xenial-16.04-amd64-server-20180306`) used to build the AMI.
+- `SourceAMITags` - The source AMI Tags, as a `map[string]string` object.
+
 ## Custom Bundle Commands
 
 A lot of the process required for creating an instance-store backed AMI involves