Update validation options for undeclared variables

In an effort to help users move from JSON to HCL2 templates the support for
variable definitions files are being updated to ignore undeclared
variable warnings on build execution. For legacy JSON templates builds no
warnings are displayed when var-files contain undeclared variables.

Since preferred mode HCL2 templates is to be explicit with variable
declarations - they must be declared to be used - validation for
undeclared variables still warns when running `packer validate`. A new
flag has been added to the validate command that can be used to disable
undeclared variable warnings.

* Update validation test for unused variables

Example Run
```
~>  go run . validate -warn-on-undeclared=false -var-file
command/test-fixtures/validate/var-file-tests/undeclared.pkrvars.hcl
command/test-fixtures/validate/var-file-tests/basic.pkr.hcl
The configuration is valid.

~>  go run . validate -var-file
command/test-fixtures/validate/var-file-tests/undeclared.pkrvars.hcl
command/test-fixtures/validate/var-file-tests/basic.pkr.hcl
Warning: Undefined variable

The variable "unused" was set but was not declared as an input variable.
To declare variable "unused" place this block in one of your .pkr.hcl
files,
such as variables.pkr.hcl

variable "unused" {
  type    = string
  default = null

}

The configuration is valid.

~>  go run . build -var-file
command/test-fixtures/validate/var-file-tests/undeclared.pkrvars.hcl
command/test-fixtures/validate/var-file-tests/basic.pkr.hcl
file.chocolate: output will be in this color.

Build 'file.chocolate' finished after 744 microseconds.

==> Wait completed after 798 microseconds

==> Builds finished. The artifacts of successful builds are:
--> file.chocolate: Stored file: chocolate.txt
```

command/build_test.go

@@ -1149,21 +1149,13 @@ func TestBuildCmd(t *testing.T) {
 			},
 			expectedCode: 0,
 			outputCheck: func(out, err string) error {
-				if !strings.Contains(out, "Warning: Undefined variable") {
-					return fmt.Errorf("expected 'Warning: Undefined variable' in output, did not find it")
-				}
-
 				nbWarns := strings.Count(out, "Warning: ")
-				if nbWarns != 1 {
+				if nbWarns != 0 {
 					return fmt.Errorf(
-						"error: too many warnings in build output, expected 1, got %d",
+						"error: too many warnings in build output, expected 0, got %d",
 						nbWarns)
 				}
 
-				if !strings.Contains(out, "variable \"testvar\" {") {
-					return fmt.Errorf("missing definition example for undefined variable")
-				}
-
 				nbErrs := strings.Count(err, "Error: ")
 				if nbErrs != 0 {
 					return fmt.Errorf("error: expected build to succeed without errors, got %d",

command/cli.go

@@ -58,7 +58,7 @@ func (ma *MetaArgs) AddFlagSets(fs *flag.FlagSet) {
 	fs.Var(&ma.ConfigType, "config-type", "set to 'hcl2' to run in hcl2 mode when no file is passed.")
 }
 
-// MetaArgs defines commonalities between all comands
+// MetaArgs defines commonalities between all commands
 type MetaArgs struct {
 	// TODO(azr): in the future, I want to allow passing multiple path to
 	// merge HCL confs together; but this will probably need an RFC first.
@@ -67,7 +67,8 @@ type MetaArgs struct {
 	Vars         map[string]string
 	VarFiles     []string
 	// set to "hcl2" to force hcl2 mode
-	ConfigType configType
+	ConfigType       configType
+	StrictValidation bool
 }
 
 func (ba *BuildArgs) AddFlagSets(flags *flag.FlagSet) {
@@ -88,9 +89,10 @@ func (ba *BuildArgs) AddFlagSets(flags *flag.FlagSet) {
 // BuildArgs represents a parsed cli line for a `packer build`
 type BuildArgs struct {
 	MetaArgs
-	Color, Debug, Force, TimestampUi, MachineReadable bool
-	ParallelBuilds                                    int64
-	OnError                                           string
+	Debug, Force                        bool
+	Color, TimestampUi, MachineReadable bool
+	ParallelBuilds                      int64
+	OnError                             string
 }
 
 func (ia *InitArgs) AddFlagSets(flags *flag.FlagSet) {
@@ -129,14 +131,15 @@ type FixArgs struct {
 
 func (va *ValidateArgs) AddFlagSets(flags *flag.FlagSet) {
 	flags.BoolVar(&va.SyntaxOnly, "syntax-only", false, "check syntax only")
+	flags.BoolVar(&va.WarnOnUndeclared, "warn-on-undeclared", true, "show warnings for pkrvars definition files containing undeclared variables")
 
 	va.MetaArgs.AddFlagSets(flags)
 }
 
 // ValidateArgs represents a parsed cli line for a `packer validate`
 type ValidateArgs struct {
 	MetaArgs
-	SyntaxOnly bool
+	SyntaxOnly, WarnOnUndeclared bool
 }
 
 func (va *InspectArgs) AddFlagSets(flags *flag.FlagSet) {

command/meta.go

@@ -136,6 +136,9 @@ func (m *Meta) GetConfigFromHCL(cla *MetaArgs) (*hcl2template.PackerConfig, int)
 		CorePackerVersionString: version.FormattedVersion(),
 		Parser:                  hclparse.NewParser(),
 		PluginConfig:            m.CoreConfig.Components.PluginConfig,
+		ValidationOptions: hcl2template.ValidationOptions{
+			Strict: cla.StrictValidation,
+		},
 	}
 	cfg, diags := parser.Parse(cla.Path, cla.VarFiles, cla.Vars)
 	return cfg, writeDiags(m.Ui, parser.Files(), diags)

command/test-fixtures/validate/var-file-tests/basic.pkr.hcl

@@ -0,0 +1,17 @@
+packer {
+  required_version = ">= v1.0.0"
+}
+
+variable "test" {
+ type = string
+ default = null
+}
+
+source "file" "chocolate" {
+  target = "chocolate.txt"
+  content = "chocolate"
+}
+
+build {
+  sources = ["source.file.chocolate"]
+}

command/test-fixtures/validate/var-file-tests/basic.pkrvars.hcl

@@ -0,0 +1 @@
+test = "myvalue"

command/test-fixtures/validate/var-file-tests/undeclared.json

@@ -0,0 +1,3 @@
+{
+    "unused": ["one", "cookie", "two", "cookie"]
+}

command/test-fixtures/validate/var-file-tests/undeclared.pkrvars.hcl

@@ -0,0 +1 @@
+unused = "unused variables should warn"

command/validate.go

@@ -45,6 +45,8 @@ func (c *ValidateCommand) ParseArgs(args []string) (*ValidateArgs, int) {
 }
 
 func (c *ValidateCommand) RunContext(ctx context.Context, cla *ValidateArgs) int {
+	cla.StrictValidation = cla.WarnOnUndeclared
+
 	packerStarter, ret := c.GetConfig(&cla.MetaArgs)
 	if ret != 0 {
 		return 1
@@ -59,6 +61,7 @@ func (c *ValidateCommand) RunContext(ctx context.Context, cla *ValidateArgs) int
 	diags := packerStarter.Initialize(packer.InitializeOptions{
 		SkipDatasourcesExecution: true,
 	})
+
 	ret = writeDiags(c.Ui, nil, diags)
 	if ret != 0 {
 		return ret
@@ -95,12 +98,13 @@ Usage: packer validate [options] TEMPLATE
 
 Options:
 
-  -syntax-only           Only check syntax. Do not verify config of the template.
-  -except=foo,bar,baz    Validate all builds other than these.
-  -machine-readable      Produce machine-readable output.
-  -only=foo,bar,baz      Validate only these builds.
-  -var 'key=value'       Variable for templates, can be used multiple times.
-  -var-file=path         JSON or HCL2 file containing user variables.
+  -syntax-only                  Only check syntax. Do not verify config of the template.
+  -except=foo,bar,baz           Validate all builds other than these.
+  -machine-readable             Produce machine-readable output.
+  -only=foo,bar,baz             Validate only these builds.
+  -var 'key=value'              Variable for templates, can be used multiple times.
+  -var-file=path                JSON or HCL2 file containing user variables.
+  -warn-on-undeclared=false     Disable warnings for JSON or HCL2  files containing undeclared variables. (Default true)
 `
 
 	return strings.TrimSpace(helpText)

command/validate_test.go

@@ -138,7 +138,7 @@ func TestValidateCommandBadVersion(t *testing.T) {
 	}
 
 	stdout, stderr := GetStdoutAndErrFromTestMeta(t, c.Meta)
-	expected := `Error: 
+	expected := `Error:
 
 This template requires Packer version 101.0.0 or higher; using 100.0.0
 
@@ -205,3 +205,132 @@ func TestValidateCommandExcept(t *testing.T) {
 		})
 	}
 }
+
+func TestValidateCommand_VarFiles(t *testing.T) {
+	tt := []struct {
+		name     string
+		path     string
+		varfile  string
+		exitCode int
+	}{
+		{name: "with basic HCL var-file definition",
+			path:     filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "basic.pkr.hcl"),
+			varfile:  filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "basic.pkrvars.hcl"),
+			exitCode: 0,
+		},
+		{name: "with unused variable in var-file definition",
+			path:     filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "basic.pkr.hcl"),
+			varfile:  filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "undeclared.pkrvars.hcl"),
+			exitCode: 0,
+		},
+		{name: "with unused variable in JSON var-file definition",
+			path:     filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "basic.pkr.hcl"),
+			varfile:  filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "undeclared.json"),
+			exitCode: 0,
+		},
+	}
+	for _, tc := range tt {
+		t.Run(tc.path, func(t *testing.T) {
+			c := &ValidateCommand{
+				Meta: TestMetaFile(t),
+			}
+			tc := tc
+			args := []string{"-var-file", tc.varfile, tc.path}
+			if code := c.Run(args); code != tc.exitCode {
+				fatalCommand(t, c.Meta)
+			}
+		})
+	}
+}
+
+func TestValidateCommand_VarFilesWarnOnUndeclared(t *testing.T) {
+	tt := []struct {
+		name     string
+		path     string
+		varfile  string
+		exitCode int
+	}{
+		{name: "warn-on-undeclared=true with unused variable in var-file definition",
+			path:     filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "basic.pkr.hcl"),
+			varfile:  filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "undeclared.pkrvars.hcl"),
+			exitCode: 0,
+		},
+		{name: "warn-on-undeclared=true with unused variable in var-file definition",
+			path:     filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "basic.pkr.hcl"),
+			varfile:  filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "undeclared.json"),
+			exitCode: 0,
+		},
+	}
+	for _, tc := range tt {
+		t.Run(tc.path, func(t *testing.T) {
+			c := &ValidateCommand{
+				Meta: TestMetaFile(t),
+			}
+			tc := tc
+			args := []string{"-var-file", tc.varfile, tc.path}
+			if code := c.Run(args); code != tc.exitCode {
+				fatalCommand(t, c.Meta)
+			}
+
+			stdout, stderr := GetStdoutAndErrFromTestMeta(t, c.Meta)
+			expected := `Warning: Undefined variable
+
+The variable "unused" was set but was not declared as an input variable.
+To declare variable "unused" place this block in one of your .pkr.hcl files,
+such as variables.pkr.hcl
+
+variable "unused" {
+  type    = string
+  default = null
+}
+
+
+The configuration is valid.
+`
+			if diff := cmp.Diff(expected, stdout); diff != "" {
+				t.Errorf("Unexpected output: %s", diff)
+			}
+			t.Log(stderr)
+		})
+	}
+}
+
+func TestValidateCommand_VarFilesDisableWarnOnUndeclared(t *testing.T) {
+	tt := []struct {
+		name     string
+		path     string
+		varfile  string
+		exitCode int
+	}{
+		{name: "warn-on-undeclared=false with unused variable in var-file definition",
+			path:     filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "basic.pkr.hcl"),
+			varfile:  filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "undeclared.pkrvars.hcl"),
+			exitCode: 0,
+		},
+		{name: "warn-on-undeclared=false with unused variable in JSON var-file definition",
+			path:     filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "basic.pkr.hcl"),
+			varfile:  filepath.Join(testFixture(filepath.Join("validate", "var-file-tests")), "undeclared.json"),
+			exitCode: 0,
+		},
+	}
+	for _, tc := range tt {
+		t.Run(tc.path, func(t *testing.T) {
+			c := &ValidateCommand{
+				Meta: TestMetaFile(t),
+			}
+			tc := tc
+			args := []string{"-warn-on-undeclared=false", "-var-file", tc.varfile, tc.path}
+			if code := c.Run(args); code != tc.exitCode {
+				fatalCommand(t, c.Meta)
+			}
+
+			stdout, stderr := GetStdoutAndErrFromTestMeta(t, c.Meta)
+			expected := `The configuration is valid.
+`
+			if diff := cmp.Diff(expected, stdout); diff != "" {
+				t.Errorf("Unexpected output: %s", diff)
+			}
+			t.Log(stderr)
+		})
+	}
+}

hcl2template/parser.go

@@ -60,9 +60,11 @@ type Parser struct {
 
 	CorePackerVersionString string
 
-	*hclparse.Parser
-
 	PluginConfig *packer.PluginConfig
+
+	ValidationOptions
+
+	*hclparse.Parser
 }
 
 const (
@@ -137,6 +139,7 @@ func (p *Parser) Parse(filename string, varFiles []string, argVars map[string]st
 		Basedir:                 basedir,
 		Cwd:                     wd,
 		CorePackerVersionString: p.CorePackerVersionString,
+		ValidationOptions:       p.ValidationOptions,
 		parser:                  p,
 		files:                   files,
 	}

hcl2template/types.variables.go

@@ -659,19 +659,19 @@ func (cfg *PackerConfig) collectInputVariableValues(env []string, files []*hcl.F
 		for name, attr := range attrs {
 			variable, found := variables[name]
 			if !found {
-				sev := hcl.DiagWarning
-				if cfg.ValidationOptions.Strict {
-					sev = hcl.DiagError
+				if cfg.ValidationOptions.Strict == false {
+					continue
 				}
+
 				diags = append(diags, &hcl.Diagnostic{
-					Severity: sev,
+					Severity: hcl.DiagWarning,
 					Summary:  "Undefined variable",
-					Detail: fmt.Sprintf("A %[1]q variable was set but was "+
-						"not declared as an input variable. To declare "+
-						"variable %[1]q, place this block in one of your "+
-						".pkr.hcl files, such as variables.pkr.hcl\n\n"+
+					Detail: fmt.Sprintf("The variable %[1]q was set but was not declared as an input variable."+
+						"\nTo declare variable %[1]q place this block in one of your .pkr.hcl files, "+
+						"such as variables.pkr.hcl\n\n"+
 						"variable %[1]q {\n"+
-						"  type = string\n"+
+						"  type    = string\n"+
+						"  default = null\n"+
 						"}",
 						name),
 					Context: attr.Range.Ptr(),

hcl2template/types.variables_test.go

@@ -476,7 +476,7 @@ func TestParse_variables(t *testing.T) {
 				},
 				Basedir: filepath.Join("testdata", "variables"),
 			},
-			true, false,
+			false, false,
 			[]packersdk.Build{
 				&packer.CoreBuild{
 					Type:           "null.test",
@@ -850,7 +850,7 @@ func TestVariables_collectVariableValues(t *testing.T) {
 			},
 
 			// output
-			wantDiags:         true,
+			wantDiags:         false,
 			wantDiagsHasError: false,
 			wantVariables:     Variables{},
 			wantValues:        map[string]cty.Value{},
@@ -867,7 +867,7 @@ func TestVariables_collectVariableValues(t *testing.T) {
 
 			// output
 			wantDiags:         true,
-			wantDiagsHasError: true,
+			wantDiagsHasError: false,
 			wantVariables:     Variables{},
 			wantValues:        map[string]cty.Value{},
 		},