Allow user to real oauth token from properly configured Vault instance

builder/googlecompute/builder.go

@@ -36,7 +36,7 @@ func (b *Builder) Prepare(raws ...interface{}) ([]string, error) {
 // representing a GCE machine image.
 func (b *Builder) Run(ctx context.Context, ui packer.Ui, hook packer.Hook) (packer.Artifact, error) {
 	driver, err := NewDriverGCE(
-		ui, b.config.ProjectId, b.config.Account)
+		ui, b.config.ProjectId, b.config.Account, b.config.VaultGCPOauthEngine)
 	if err != nil {
 		return nil, err
 	}

builder/googlecompute/config.go

@@ -165,6 +165,18 @@ type Config struct {
 	// If true, use the instance's internal IP instead of its external IP
 	// during building.
 	UseInternalIP bool `mapstructure:"use_internal_ip" required:"false"`
+	// Can be set instead of account_file. If set, this builder will use
+	// HashiCorp Vault to generate an Oauth token for authenticating against
+	// Google's cloud. The value should be the path of the token generator
+	// within vault.
+	// For information on how to configure your Vault + GCP engine to produce
+	// Oauth tokens, see https://www.vaultproject.io/docs/auth/gcp.html
+	// You must have the environment variables VAULT_ADDR and VAULT_TOKEN set,
+	// along with any other relevant variables for accessing your vault
+	// instance. For more information, see the Vault docs:
+	// https://www.vaultproject.io/docs/commands/#environment-variables
+	// Example:`"vault_gcp_oauth_engine": "gcp/token/my-project-editor",`
+	VaultGCPOauthEngine string `mapstructure:"vault_gcp_oauth_engine"`
 	// The zone in which to launch the instance used to create the image.
 	// Example: "us-central1-a"
 	Zone string `mapstructure:"zone" required:"true"`
@@ -322,7 +334,12 @@ func NewConfig(raws ...interface{}) (*Config, []string, error) {
 		errs = packer.MultiErrorAppend(errs, err)
 	}
 
+	// Authenticating via an account file
 	if c.AccountFile != "" {
+		if c.VaultGCPOauthEngine != "" {
+			errs = packer.MultiErrorAppend(errs, fmt.Errorf("You cannot "+
+				"specify both account_file and vault_gcp_oauth_engine."))
+		}
 		cfg, err := ProcessAccountFile(c.AccountFile)
 		if err != nil {
 			errs = packer.MultiErrorAppend(errs, err)

builder/googlecompute/driver_gce.go

@@ -19,6 +19,7 @@ import (
 	"github.com/hashicorp/packer/common/retry"
 	"github.com/hashicorp/packer/helper/useragent"
 	"github.com/hashicorp/packer/packer"
+	vaultapi "github.com/hashicorp/vault/api"
 
 	"golang.org/x/oauth2"
 	"golang.org/x/oauth2/google"
@@ -35,13 +36,52 @@ type driverGCE struct {
 
 var DriverScopes = []string{"https://www.googleapis.com/auth/compute", "https://www.googleapis.com/auth/devstorage.full_control"}
 
-func NewClientGCE(conf *jwt.Config) (*http.Client, error) {
+// Define a TokenSource that gets tokens from Vault
+type OauthTokenSource struct {
+	Path string
+}
+
+func (ots OauthTokenSource) Token() (*oauth2.Token, error) {
+	log.Printf("Retrieving Oauth token from Vault...")
+	vaultConfig := vaultapi.DefaultConfig()
+	cli, err := vaultapi.NewClient(vaultConfig)
+	if err != nil {
+		return nil, fmt.Errorf("%s\n", err)
+	}
+	resp, err := cli.Logical().Read(ots.Path)
+	if err != nil {
+		return nil, fmt.Errorf("Error reading vault resp: %s", err)
+	}
+	if resp == nil {
+		return nil, fmt.Errorf("Vault Oauth Engine does not exist at the given path.")
+	}
+	token, ok := resp.Data["token"]
+	if !ok {
+		return nil, fmt.Errorf("ERROR, token was not present in response body")
+	}
+	at := token.(string)
+
+	log.Printf("Retrieved Oauth token from Vault")
+	return &oauth2.Token{
+		AccessToken: at,
+		Expiry:      time.Now().Add(time.Minute * time.Duration(60)),
+	}, nil
+
+}
+
+func NewClientGCE(conf *jwt.Config, vaultOauth string) (*http.Client, error) {
 	var err error
 
 	var client *http.Client
 
-	// Auth with AccountFile first if provided
-	if conf != nil && len(conf.PrivateKey) > 0 {
+	if vaultOauth != "" {
+		// Auth with Vault Oauth
+		log.Printf("Using Vault to generate Oauth token.")
+		ts := OauthTokenSource{vaultOauth}
+		return oauth2.NewClient(oauth2.NoContext, ts), nil
+
+	} else if conf != nil && len(conf.PrivateKey) > 0 {
+		// Auth with AccountFile if provided
 		log.Printf("[INFO] Requesting Google token via account_file...")
 		log.Printf("[INFO]   -- Email: %s", conf.Email)
 		log.Printf("[INFO]   -- Scopes: %s", DriverScopes)
@@ -75,8 +115,8 @@ func NewClientGCE(conf *jwt.Config) (*http.Client, error) {
 	return client, nil
 }
 
-func NewDriverGCE(ui packer.Ui, p string, conf *jwt.Config) (Driver, error) {
-	client, err := NewClientGCE(conf)
+func NewDriverGCE(ui packer.Ui, p string, conf *jwt.Config, vaultOauth string) (Driver, error) {
+	client, err := NewClientGCE(conf, vaultOauth)
 	if err != nil {
 		return nil, err
 	}

post-processor/googlecompute-export/post-processor.go

@@ -25,6 +25,7 @@ type Config struct {
 	Network             string   `mapstructure:"network"`
 	Paths               []string `mapstructure:"paths"`
 	Subnetwork          string   `mapstructure:"subnetwork"`
+	VaultGCPOauthEngine string   `mapstructure:"vault_gcp_oauth_engine"`
 	Zone                string   `mapstructure:"zone"`
 
 	Account *jwt.Config
@@ -69,6 +70,12 @@ func (p *PostProcessor) Configure(raws ...interface{}) error {
 		p.config.Network = "default"
 	}
 
+	if p.config.AccountFile != "" && p.config.VaultGCPOauthEngine != "" {
+		errs = packer.MultiErrorAppend(
+			errs, fmt.Errorf("May set either account_file or "+
+				"vault_gcp_oauth_engine, but not both."))
+	}
+
 	if len(errs.Errors) > 0 {
 		return errs
 	}
@@ -142,7 +149,8 @@ func (p *PostProcessor) PostProcess(ctx context.Context, ui packer.Ui, artifact
 	}
 	exporterConfig.CalcTimeout()
 
-	driver, err := googlecompute.NewDriverGCE(ui, builderProjectId, p.config.Account)
+	driver, err := googlecompute.NewDriverGCE(ui, builderProjectId,
+		p.config.Account, p.config.VaultGCPOauthEngine)
 	if err != nil {
 		return nil, false, false, err
 	}

post-processor/googlecompute-import/post-processor.go

@@ -34,6 +34,7 @@ type Config struct {
 	ImageLabels          map[string]string `mapstructure:"image_labels"`
 	ImageName            string            `mapstructure:"image_name"`
 	SkipClean            bool              `mapstructure:"skip_clean"`
+	VaultGCPOauthEngine  string            `mapstructure:"vault_gcp_oauth_engine"`
 
 	Account *jwt.Config
 	ctx     interpolate.Context
@@ -78,6 +79,12 @@ func (p *PostProcessor) Configure(raws ...interface{}) error {
 		p.config.Account = cfg
 	}
 
+	if p.config.AccountFile != "" && p.config.VaultGCPOauthEngine != "" {
+		errs = packer.MultiErrorAppend(
+			errs, fmt.Errorf("May set either account_file or "+
+				"vault_gcp_oauth_engine, but not both."))
+	}
+
 	templates := map[string]*string{
 		"bucket":     &p.config.Bucket,
 		"image_name": &p.config.ImageName,
@@ -98,7 +105,7 @@ func (p *PostProcessor) Configure(raws ...interface{}) error {
 }
 
 func (p *PostProcessor) PostProcess(ctx context.Context, ui packer.Ui, artifact packer.Artifact) (packer.Artifact, bool, bool, error) {
-	client, err := googlecompute.NewClientGCE(p.config.Account)
+	client, err := googlecompute.NewClientGCE(p.config.Account, p.config.VaultGCPOauthEngine)
 	if err != nil {
 		return nil, false, false, err
 	}

website/source/partials/builder/googlecompute/_Config-not-required.html.md

@@ -125,3 +125,15 @@
 -   `use_internal_ip` (bool) - If true, use the instance's internal IP instead of its external IP
     during building.
     
+-   `vault_gcp_oauth_engine` (string) - Can be set instead of account_file. If set, this builder will use
+    HashiCorp Vault to generate an Oauth token for authenticating against
+    Google's cloud. The value should be the path of the token generator
+    within vault.
+    For information on how to configure your Vault + GCP engine to produce
+    Oauth tokens, see https://www.vaultproject.io/docs/auth/gcp.html
+    You must have the environment variables VAULT_ADDR and VAULT_TOKEN set,
+    along with any other relevant variables for accessing your vault
+    instance. For more information, see the Vault docs:
+    https://www.vaultproject.io/docs/commands/#environment-variables
+    Example:`"vault_gcp_oauth_engine": "gcp/token/my-project-editor",`
+