configs/configupgrade: Upgrade the bodies of "provisioner" blocks

Aside from the two special meta-arguments "connection" and "provisioner"
this is just our standard mapping from schema to conversion rules, using
the provisioner's configuration schema.

configs/configupgrade/test-fixtures/valid/noop/input/resources.tf

@@ -3,7 +3,7 @@ resource "test_instance" "example" {
   connection {
     host = "127.0.0.1"
   }
-  provisioner "local-exec" {
+  provisioner "test" {
     connection {
       host = "127.0.0.2"
     }

configs/configupgrade/test-fixtures/valid/noop/want/resources.tf

@@ -3,7 +3,7 @@ resource "test_instance" "example" {
   connection {
     host = "127.0.0.1"
   }
-  provisioner "local-exec" {
+  provisioner "test" {
     connection {
       host = "127.0.0.2"
     }

configs/configupgrade/test-fixtures/valid/provisioner/input/provisioner.tf

@@ -0,0 +1,8 @@
+resource "test_instance" "foo" {
+  provisioner "test" {
+    commands = "${list("a", "b", "c")}"
+
+    when       = "create"
+    on_failure = "fail"
+  }
+}

configs/configupgrade/test-fixtures/valid/provisioner/want/provisioner.tf

@@ -0,0 +1,8 @@
+resource "test_instance" "foo" {
+  provisioner "test" {
+    commands = ["a", "b", "c"]
+
+    when       = create
+    on_failure = fail
+  }
+}

configs/configupgrade/test-fixtures/valid/provisioner/want/versions.tf

@@ -0,0 +1,3 @@
+terraform {
+  required_version = ">= 0.12"
+}

configs/configupgrade/upgrade_body.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	hcl1ast "github.com/hashicorp/hcl/hcl/ast"
+	hcl1printer "github.com/hashicorp/hcl/hcl/printer"
 	hcl1token "github.com/hashicorp/hcl/hcl/token"
 	hcl2 "github.com/hashicorp/hcl2/hcl"
 	hcl2syntax "github.com/hashicorp/hcl2/hcl/hclsyntax"
@@ -554,3 +555,69 @@ func lifecycleBlockBodyRules(filename string, an *analysis) bodyContentRules {
 		},
 	}
 }
+
+func provisionerBlockRule(filename string, an *analysis, adhocComments *commentQueue) bodyItemRule {
+	// Unlike some other examples above, this is a rule for the entire
+	// provisioner block, rather than just for its contents. Therefore it must
+	// also produce the block header and body delimiters.
+	return func(buf *bytes.Buffer, blockAddr string, item *hcl1ast.ObjectItem) tfdiags.Diagnostics {
+		var diags tfdiags.Diagnostics
+		body := item.Val.(*hcl1ast.ObjectType)
+		declRange := hcl1PosRange(filename, item.Keys[0].Pos())
+
+		if len(item.Keys) < 2 {
+			diags = diags.Append(&hcl2.Diagnostic{
+				Severity: hcl2.DiagError,
+				Summary:  "Invalid provisioner block",
+				Detail:   "A provisioner block must have one label: the provisioner type.",
+				Subject:  &declRange,
+			})
+			return diags
+		}
+
+		typeName := item.Keys[1].Token.Value().(string)
+		schema := an.ProvisionerSchemas[typeName]
+		if schema == nil {
+			// This message is assuming that if the user _is_ using a third-party
+			// provisioner plugin they already know how to install it for normal
+			// use and so we don't need to spell out those instructions in detail
+			// here.
+			diags = diags.Append(&hcl2.Diagnostic{
+				Severity: hcl2.DiagError,
+				Summary:  "Unknown provisioner type",
+				Detail:   fmt.Sprintf("The provisioner type %q is not supported. If this is a third-party plugin, make sure its plugin executable is available in one of the usual plugin search paths.", typeName),
+				Subject:  &declRange,
+			})
+			return diags
+		}
+
+		rules := schemaDefaultBodyRules(filename, schema, an, adhocComments)
+		rules["when"] = maybeBareTraversalAttributeRule(filename, an)
+		rules["on_failure"] = maybeBareTraversalAttributeRule(filename, an)
+		rules["connection"] = connectionBlockRule(filename, an, adhocComments)
+
+		printComments(buf, item.LeadComment)
+		printBlockOpen(buf, "provisioner", []string{typeName}, item.LineComment)
+		bodyDiags := upgradeBlockBody(filename, fmt.Sprintf("%s.provisioner[%q]", blockAddr, typeName), buf, body.List.Items, body.Rbrace, rules, adhocComments)
+		diags = diags.Append(bodyDiags)
+		buf.WriteString("}\n")
+
+		return diags
+	}
+}
+
+func connectionBlockRule(filename string, an *analysis, adhocComments *commentQueue) bodyItemRule {
+	// Unlike some other examples above, this is a rule for the entire
+	// connection block, rather than just for its contents. Therefore it must
+	// also produce the block header and body delimiters.
+	return func(buf *bytes.Buffer, blockAddr string, item *hcl1ast.ObjectItem) tfdiags.Diagnostics {
+		// TODO: For the few resource types that were setting ConnInfo in
+		// state after create/update in prior versions, generate the additional
+		// explicit connection settings that are now required if and only if
+		// there's at least one provisioner block.
+		// For now, we just pass this through as-is.
+		hcl1printer.Fprint(buf, item)
+		buf.WriteByte('\n')
+		return nil
+	}
+}

configs/configupgrade/upgrade_native.go

@@ -329,24 +329,8 @@ func (u *Upgrader) upgradeNativeSyntaxResource(filename string, buf *bytes.Buffe
 	rules["depends_on"] = dependsOnAttributeRule(filename, an)
 	rules["provider"] = maybeBareTraversalAttributeRule(filename, an)
 	rules["lifecycle"] = nestedBlockRule(filename, lifecycleBlockBodyRules(filename, an), an, adhocComments)
-	rules["connection"] = func(buf *bytes.Buffer, blockAddr string, item *hcl1ast.ObjectItem) tfdiags.Diagnostics {
-		// TODO: For the few resource types that were setting ConnInfo in
-		// state after create/update in prior versions, generate the additional
-		// explicit connection settings that are now required if and only if
-		// there's at least one provisioner block.
-		// For now, we just pass this through as-is.
-		hcl1printer.Fprint(buf, item)
-		buf.WriteByte('\n')
-		return nil
-	}
-	rules["provisioner"] = func(buf *bytes.Buffer, blockAddr string, item *hcl1ast.ObjectItem) tfdiags.Diagnostics {
-		// TODO: Look up the provisioner schema and map this properly to ensure
-		// any references get properly updated.
-		// For now, we just pass this through as-is.
-		hcl1printer.Fprint(buf, item)
-		buf.WriteByte('\n')
-		return nil
-	}
+	rules["connection"] = connectionBlockRule(filename, an, adhocComments)
+	rules["provisioner"] = provisionerBlockRule(filename, an, adhocComments)
 
 	printComments(buf, item.LeadComment)
 	printBlockOpen(buf, blockType, labels, item.LineComment)

configs/configupgrade/upgrade_test.go

@@ -17,6 +17,7 @@ import (
 	"github.com/hashicorp/terraform/configs/configschema"
 	"github.com/hashicorp/terraform/helper/logging"
 	"github.com/hashicorp/terraform/providers"
+	"github.com/hashicorp/terraform/provisioners"
 	"github.com/hashicorp/terraform/terraform"
 )
 
@@ -40,6 +41,7 @@ func TestUpgradeValid(t *testing.T) {
 			wantDir := filepath.Join(fixtureDir, entry.Name(), "want")
 			u := &Upgrader{
 				Providers:    providers.ResolverFixed(testProviders),
+				Provisioners: testProvisioners,
 			}
 
 			inputSrc, err := LoadModule(inputDir)
@@ -250,6 +252,21 @@ var testProviders = map[string]providers.Factory{
 	}),
 }
 
+var testProvisioners = map[string]provisioners.Factory{
+	"test": provisioners.Factory(func() (provisioners.Interface, error) {
+		p := &terraform.MockProvisioner{}
+		p.GetSchemaResponse = provisioners.GetSchemaResponse{
+			Provisioner: &configschema.Block{
+				Attributes: map[string]*configschema.Attribute{
+					"commands":    {Type: cty.List(cty.String), Optional: true},
+					"interpreter": {Type: cty.String, Optional: true},
+				},
+			},
+		}
+		return p, nil
+	}),
+}
+
 func init() {
 	// Initialize the backends
 	backendinit.Init(nil)