HCL2: allow to use keep_input_artifact in post processors (#9477)

* HCL2: allow to use keep_input_artifact in post processors
* add basic test
* add docs

hcl2template/testdata/complete/build.pkr.hcl

@@ -124,6 +124,7 @@ build {
         bool     = true
         trilean  = true
         duration = "10s"
+        keep_input_artifact = true
         map_string_string = {
             a = "b"
             c = "d"

hcl2template/types.build.post-processor.go

@@ -10,9 +10,10 @@ import (
 
 // ProvisionerBlock references a detected but unparsed post processor
 type PostProcessorBlock struct {
-	PType      string
-	PName      string
-	OnlyExcept OnlyExcept
+	PType             string
+	PName             string
+	OnlyExcept        OnlyExcept
+	KeepInputArtifact *bool
 
 	HCL2Ref
 }
@@ -23,10 +24,11 @@ func (p *PostProcessorBlock) String() string {
 
 func (p *Parser) decodePostProcessor(block *hcl.Block) (*PostProcessorBlock, hcl.Diagnostics) {
 	var b struct {
-		Name   string   `hcl:"name,optional"`
-		Only   []string `hcl:"only,optional"`
-		Except []string `hcl:"except,optional"`
-		Rest   hcl.Body `hcl:",remain"`
+		Name              string   `hcl:"name,optional"`
+		Only              []string `hcl:"only,optional"`
+		Except            []string `hcl:"except,optional"`
+		KeepInputArtifact *bool    `hcl:"keep_input_artifact,optional"`
+		Rest              hcl.Body `hcl:",remain"`
 	}
 	diags := gohcl.DecodeBody(block.Body, nil, &b)
 	if diags.HasErrors() {
@@ -34,10 +36,11 @@ func (p *Parser) decodePostProcessor(block *hcl.Block) (*PostProcessorBlock, hcl
 	}
 
 	postProcessor := &PostProcessorBlock{
-		PType:      block.Labels[0],
-		PName:      b.Name,
-		OnlyExcept: OnlyExcept{Only: b.Only, Except: b.Except},
-		HCL2Ref:    newHCL2Ref(block, b.Rest),
+		PType:             block.Labels[0],
+		PName:             b.Name,
+		OnlyExcept:        OnlyExcept{Only: b.Only, Except: b.Except},
+		HCL2Ref:           newHCL2Ref(block, b.Rest),
+		KeepInputArtifact: b.KeepInputArtifact,
 	}
 
 	diags = diags.Extend(postProcessor.OnlyExcept.Validate())

hcl2template/types.packer_config.go

@@ -271,9 +271,10 @@ func (cfg *PackerConfig) getCoreBuildPostProcessors(source SourceBlock, blocks [
 			continue
 		}
 		res = append(res, packer.CoreBuildPostProcessor{
-			PostProcessor: postProcessor,
-			PName:         ppb.PName,
-			PType:         ppb.PType,
+			PostProcessor:     postProcessor,
+			PName:             ppb.PName,
+			PType:             ppb.PType,
+			KeepInputArtifact: ppb.KeepInputArtifact,
 		})
 	}
 

hcl2template/types.packer_config_test.go

@@ -11,6 +11,7 @@ import (
 var (
 	refVBIsoUbuntu1204  = SourceRef{Type: "virtualbox-iso", Name: "ubuntu-1204"}
 	refAWSEBSUbuntu1604 = SourceRef{Type: "amazon-ebs", Name: "ubuntu-1604"}
+	pTrue               = pointerToBool(true)
 )
 
 func TestParser_complete(t *testing.T) {
@@ -90,8 +91,9 @@ func TestParser_complete(t *testing.T) {
 						},
 						PostProcessors: []*PostProcessorBlock{
 							{
-								PType: "amazon-import",
-								PName: "something",
+								PType:             "amazon-import",
+								PName:             "something",
+								KeepInputArtifact: pTrue,
 							},
 							{
 								PType: "amazon-import",
@@ -117,9 +119,10 @@ func TestParser_complete(t *testing.T) {
 					PostProcessors: [][]packer.CoreBuildPostProcessor{
 						{
 							{
-								PType:         "amazon-import",
-								PName:         "something",
-								PostProcessor: basicMockPostProcessor,
+								PType:             "amazon-import",
+								PName:             "something",
+								PostProcessor:     basicMockPostProcessor,
+								KeepInputArtifact: pTrue,
 							},
 							{
 								PType:         "amazon-import",
@@ -152,9 +155,10 @@ func TestParser_complete(t *testing.T) {
 					PostProcessors: [][]packer.CoreBuildPostProcessor{
 						{
 							{
-								PType:         "amazon-import",
-								PName:         "something",
-								PostProcessor: basicMockPostProcessor,
+								PType:             "amazon-import",
+								PName:             "something",
+								PostProcessor:     basicMockPostProcessor,
+								KeepInputArtifact: pTrue,
 							},
 							{
 								PType:         "amazon-import",
@@ -191,3 +195,7 @@ func TestParser_ValidateFilterOption(t *testing.T) {
 		})
 	}
 }
+
+func pointerToBool(b bool) *bool {
+	return &b
+}

packer/build.go

@@ -115,7 +115,7 @@ type CoreBuildPostProcessor struct {
 	PType             string
 	PName             string
 	config            map[string]interface{}
-	keepInputArtifact *bool
+	KeepInputArtifact *bool
 }
 
 // CoreBuildProvisioner keeps track of the provisioner and the configuration of
@@ -341,15 +341,15 @@ PostProcessorRunSeqLoop:
 			// Exception: for postprocessors that will fail/become
 			// useless if keep isn't true, heed forceOverride and keep the
 			// input artifact regardless of user preference.
-			if corePP.keepInputArtifact != nil {
-				if defaultKeep && *corePP.keepInputArtifact == false && forceOverride {
+			if corePP.KeepInputArtifact != nil {
+				if defaultKeep && *corePP.KeepInputArtifact == false && forceOverride {
 					log.Printf("The %s post-processor forces "+
 						"keep_input_artifact=true to preserve integrity of the"+
 						"build chain. User-set keep_input_artifact=false will be"+
 						"ignored.", corePP.PType)
 				} else {
 					// User overrides default.
-					keep = *corePP.keepInputArtifact
+					keep = *corePP.KeepInputArtifact
 				}
 			}
 			if i == 0 {

packer/core.go

@@ -341,7 +341,7 @@ func (c *Core) Build(n string) (Build, error) {
 				PType:             rawP.Type,
 				PName:             rawP.Name,
 				config:            rawP.Config,
-				keepInputArtifact: rawP.KeepInputArtifact,
+				KeepInputArtifact: rawP.KeepInputArtifact,
 			})
 		}
 

website/pages/docs/from-1.5/blocks/build/post-processor.mdx

@@ -17,8 +17,8 @@ The `post-processor` block defines how a post-processor is configured.
 build {
   # ...
   post-processor "checksum" {
-    checksum_types = [ "md5", "sha512" ]
-    keep_input_artifact = true
+    checksum_types = [ "md5", "sha512" ] # checksum the artifact
+    keep_input_artifact = true           # keep the artifact
   }
 }
 ```
@@ -28,12 +28,32 @@ the provisioner(s). Post-processors are optional, and they can be used to
 upload artifacts, re-package, or more. The list of available post-processors
 can be found in the [post-processors](/docs/post-processors) section.
 
+-> Note: The input 'artifact' received by a post-processor will be automatically
+  deleted.
+
+# Keep an input artifact
+
+To prevent an input artifact from being deleted, you can set the
+`keep_input_artifact` field to true to make Packer keep both artifacts. For
+example if we want to checksum an artifact and keep the artifact:
+
+```hcl
+# builds.pkr.hcl
+build {
+  # ...
+  post-processor "checksum" {
+    checksum_types = [ "md5", "sha512" ]
+    keep_input_artifact = true
+  }
+}
+```
+
 # Run on Specific Builds
 
 You can use the `only` or `except` configurations to run a post-processor only
-with specific builds. These two configurations do what you expect: `only` will
-only run the post-processor on the specified builds and `except` will run the
-post-processor on anything other than the specified builds.
+with specific sources. These two configurations do what you expect: `only` will
+only run the post-processor on the specified sources and `except` will run the
+post-processor on anything other than the specified sources.
 
 An example of `only` being used is shown below, but the usage of `except` is
 effectively the same:
@@ -50,4 +70,4 @@ build {
 }
 ```
 
-The values within `only` or `except` are _build names_, not builder types.
+The values within `only` or `except` are _source names_, not builder types.