builder/amazon/common: save access/secret key from env [GH-434]

CHANGELOG.md

@@ -16,6 +16,8 @@ BUG FIXES:
   instance, etc.) disappears from under it.
 * builder/amazon/instance: Exclude only contents of /tmp, not /tmp
   itself. [GH-437]
+* builder/amazon/instance: Make AccessKey/SecretKey available to bundle
+  command even when they come from the environment. [GH-434]
 * builder/virtualbox: F1-F12 and delete scancodes now work. [GH-425]
 * provisioner/puppet-masterless: Fix failure case when both facter vars
   are used and prevent_sudo. [GH-415]

builder/amazon/common/access_config.go

@@ -18,7 +18,14 @@ type AccessConfig struct {
 // Auth returns a valid aws.Auth object for access to AWS services, or
 // an error if the authentication couldn't be resolved.
 func (c *AccessConfig) Auth() (aws.Auth, error) {
-	return aws.GetAuth(c.AccessKey, c.SecretKey)
+	auth, err := aws.GetAuth(c.AccessKey, c.SecretKey)
+	if err == nil {
+		// Store the accesskey and secret that we got...
+		c.AccessKey = auth.AccessKey
+		c.SecretKey = auth.SecretKey
+	}
+
+	return auth, err
 }
 
 // Region returns the aws.Region object for access to AWS services, requesting