reorganize placeholder data call to live with provisioner implementation; force users to use the generated function, therefore forcing validation, for all variables except winrmpassword, by doing a simple string check against the placeholder data.

common/shell-local/config.go

@@ -10,7 +10,6 @@ import (
 	"runtime"
 	"strings"
 
-	"github.com/hashicorp/packer/common"
 	"github.com/hashicorp/packer/common/shell"
 	configHelper "github.com/hashicorp/packer/helper/config"
 	"github.com/hashicorp/packer/packer"
@@ -52,7 +51,7 @@ type Config struct {
 func Decode(config *Config, raws ...interface{}) error {
 	// Create passthrough for build-generated data so we can fill it in once we know
 	// it
-	config.ctx.Data = common.PlaceholderData()
+	config.ctx.Data = packer.BasicPlaceholderData()
 
 	err := configHelper.Decode(&config, &configHelper.DecodeOpts{
 		Interpolate:        true,

common/step_provision.go

@@ -22,34 +22,6 @@ import (
 // Produces:
 //   <nothing>
 
-// Provisioners interpolate most of their fields in the prepare stage; this
-// placeholder map helps keep fields that are only generated at build time from
-// accidentally being interpolated into empty strings at prepare time.
-func PlaceholderData() map[string]string {
-	placeholderData := map[string]string{}
-	placeholderData["ID"] = "{{.ID}}"
-	// The following correspond to communicator-agnostic functions that are
-	// part of the SSH and WinRM communicator implementations. These functions
-	// are not part of the communicator interface, but are stored on the
-	// Communicator Config and return the appropriate values rather than
-	// depending on the actual communicator config values. E.g "Password"
-	// reprosents either WinRMPassword or SSHPassword, which makes this more
-	// useful if a template contains multiple builds.
-	placeholderData["Host"] = "{{.Host}}"
-	placeholderData["Port"] = "{{.Port}}"
-	placeholderData["User"] = "{{.User}}"
-	placeholderData["Password"] = "{{.Password}}"
-	placeholderData["ConnType"] = "{{.Type}}"
-	placeholderData["PACKER_RUN_UUID"] = "{{.PACKER_RUN_UUID}}"
-	placeholderData["SSHPublicKey"] = "{{.SSHPublicKey}}"
-	placeholderData["SSHPrivateKey"] = "{{.SSHPrivateKey}}"
-
-	// Backwards-compatability:
-	placeholderData["WinRMPassword"] = "{{.WinRMPassword}}"
-
-	return placeholderData
-}
-
 func PopulateProvisionHookData(state multistep.StateBag) map[string]interface{} {
 	hookData := map[string]interface{}{}
 	// instance_id is placed in state by the builders.

helper/common/shared_state.go

@@ -7,6 +7,11 @@ import (
 	"path/filepath"
 )
 
+// This is used in the BasicPlaceholderData() func in the packer/provisioner.go
+// To force users to access generated data via the "generated" func.
+const PlaceholderMsg = "To set this dynamically in the Packer template, " +
+	"you must use the `generated` function"
+
 // Used to set variables which we need to access later in the build, where
 // state bag and config information won't work
 func sharedStateFilename(suffix string, buildName string) string {

packer/provisioner.go

@@ -6,6 +6,8 @@ import (
 	"log"
 	"sync"
 	"time"
+
+	"github.com/hashicorp/packer/helper/common"
 )
 
 // A provisioner is responsible for installing and configuring software
@@ -37,6 +39,42 @@ type ProvisionHook struct {
 	Provisioners []*HookedProvisioner
 }
 
+// Provisioners interpolate most of their fields in the prepare stage; this
+// placeholder map helps keep fields that are only generated at build time from
+// accidentally being interpolated into empty strings at prepare time.
+// This helper function generates the most basic placeholder data which should
+// be accessible to the provisioners. It is used to initialize provisioners, to
+// force validation using the `generated` template function. In the future,
+// custom generated data could be passed into provisioners from builders to
+// enable specialized builder-specific (but still validated!!) access to builder
+// data.
+func BasicPlaceholderData() map[string]string {
+	placeholderData := map[string]string{}
+	msg := "Generated_%s. " + common.PlaceholderMsg
+	placeholderData["ID"] = fmt.Sprintf(msg, "ID")
+	// The following correspond to communicator-agnostic functions that are
+	// part of the SSH and WinRM communicator implementations. These functions
+	// are not part of the communicator interface, but are stored on the
+	// Communicator Config and return the appropriate values rather than
+	// depending on the actual communicator config values. E.g "Password"
+	// reprosents either WinRMPassword or SSHPassword, which makes this more
+	// useful if a template contains multiple builds.
+	placeholderData["Host"] = fmt.Sprintf(msg, "Host")
+	placeholderData["Port"] = fmt.Sprintf(msg, "Port")
+	placeholderData["User"] = fmt.Sprintf(msg, "User")
+	placeholderData["Password"] = fmt.Sprintf(msg, "Password")
+	placeholderData["ConnType"] = fmt.Sprintf(msg, "Type")
+	placeholderData["PACKER_RUN_UUID"] = fmt.Sprintf(msg, "PACKER_RUN_UUID")
+	placeholderData["SSHPublicKey"] = fmt.Sprintf(msg, "SSHPublicKey")
+	placeholderData["SSHPrivateKey"] = fmt.Sprintf(msg, "SSHPrivateKey")
+
+	// Backwards-compatability: WinRM Password can get through without forcing
+	// the generated func validation.
+	placeholderData["WinRMPassword"] = "{{.WinRMPassword}}"
+
+	return placeholderData
+}
+
 // Runs the provisioners in order.
 func (h *ProvisionHook) Run(ctx context.Context, name string, ui Ui, comm Communicator, data interface{}) error {
 	// Shortcut

provisioner/ansible/provisioner.go

@@ -81,7 +81,7 @@ func (p *Provisioner) Prepare(raws ...interface{}) error {
 	p.done = make(chan struct{})
 
 	// Create passthrough for build-generated data
-	p.config.ctx.Data = common.PlaceholderData()
+	p.config.ctx.Data = packer.BasicPlaceholderData()
 
 	err := config.Decode(&p.config, &config.DecodeOpts{
 		Interpolate:        true,

provisioner/chef-client/provisioner.go

@@ -121,7 +121,7 @@ type KnifeTemplate struct {
 
 func (p *Provisioner) Prepare(raws ...interface{}) error {
 	// Create passthrough for build-generated data
-	p.config.ctx.Data = common.PlaceholderData()
+	p.config.ctx.Data = packer.BasicPlaceholderData()
 	err := config.Decode(&p.config, &config.DecodeOpts{
 		Interpolate:        true,
 		InterpolateContext: &p.config.ctx,

provisioner/powershell/provisioner.go

@@ -90,7 +90,7 @@ func (p *Provisioner) defaultExecuteCommand() string {
 
 func (p *Provisioner) Prepare(raws ...interface{}) error {
 	// Create passthrough for build-generated data
-	p.config.ctx.Data = common.PlaceholderData()
+	p.config.ctx.Data = packer.BasicPlaceholderData()
 
 	err := config.Decode(&p.config, &config.DecodeOpts{
 		Interpolate:        true,

provisioner/puppet-masterless/provisioner.go

@@ -148,7 +148,7 @@ type ExecuteTemplate struct {
 
 func (p *Provisioner) Prepare(raws ...interface{}) error {
 	// Create passthrough for build-generated data
-	p.config.ctx.Data = common.PlaceholderData()
+	p.config.ctx.Data = packer.BasicPlaceholderData()
 	err := config.Decode(&p.config, &config.DecodeOpts{
 		Interpolate:        true,
 		InterpolateContext: &p.config.ctx,

provisioner/puppet-server/provisioner.go

@@ -142,7 +142,7 @@ type ExecuteTemplate struct {
 
 func (p *Provisioner) Prepare(raws ...interface{}) error {
 	// Create passthrough for build-generated data
-	p.config.ctx.Data = common.PlaceholderData()
+	p.config.ctx.Data = packer.BasicPlaceholderData()
 
 	err := config.Decode(&p.config, &config.DecodeOpts{
 		Interpolate:        true,

template/interpolate/funcs.go

@@ -12,6 +12,7 @@ import (
 
 	consulapi "github.com/hashicorp/consul/api"
 	"github.com/hashicorp/packer/common/uuid"
+	"github.com/hashicorp/packer/helper/common"
 	"github.com/hashicorp/packer/version"
 	vaultapi "github.com/hashicorp/vault/api"
 	strftime "github.com/jehiah/go-strftime"
@@ -166,11 +167,17 @@ func funcGenTemplateDir(ctx *Context) interface{} {
 func funcGenGenerated(ctx *Context) interface{} {
 	return func(s string) (string, error) {
 		if data, ok := ctx.Data.(map[string]string); ok {
-			// PlaceholderData has been passed into generator, and we can check
-			// the value against the placeholder data to make sure that it is
-			// valid
+			// PlaceholderData has been passed into generator, so if the given
+			// key already exists in data, then we know it's an "allowed" key
 			if heldPlace, ok := data[s]; ok {
-				return heldPlace, nil
+				// If we're in the first interpolation pass, the goal is to
+				// make sure that we pass the value through.
+				// TODO match against an actual string constant
+				if strings.Contains(heldPlace, common.PlaceholderMsg) {
+					return fmt.Sprintf("{{.%s}}", s), nil
+				} else {
+					return heldPlace, nil
+				}
 			} else {
 				return "", fmt.Errorf("loaded data, but couldnt find %s in it", s)
 			}