Merge pull request #47 from nathandines/assume-role-refinement

Re-release: v0.1.2

README.md

@@ -30,6 +30,8 @@ state of the stack deployment.
 - Acceptance of "No updates to be performed." as a non-erroneous state
 - Environment Variable Substitution in Parameter and Tag files
 - YAML and JSON formatted stack policies
+- Deploy using an assumed IAM role (often used to deploy stacks to other
+  accounts)
 
 More features are currently on the roadmap, which can be [found on
 Trello](https://trello.com/b/ECuGN86A)

commands/deploy.go

@@ -69,7 +69,7 @@ var deployCmd = &cobra.Command{
 		}
 
 		// Populate Stack ID
-		// Deliberately ignore errors here
+		// Deliberately ignore errors here, as the stack might not exist yet
 		stack.GetStackInfo()
 
 		after, err := stack.GetLastEventTime()
@@ -90,9 +90,12 @@ var deployCmd = &cobra.Command{
 		}
 
 		for {
-			// Refresh Stack State
+		refresh_stack_status:
 			if err := stack.GetStackInfo(); err != nil {
-				log.Fatal(err)
+				if err2 := rotateRoleCredentials(err); err2 != nil {
+					log.Fatal(err)
+				}
+				goto refresh_stack_status
 			}
 
 			printStackEvents(&stack, after)

commands/destroy.go

@@ -35,9 +35,12 @@ var destroyCmd = &cobra.Command{
 		}
 
 		for {
-			// Refresh Stack State
+		refresh_stack_status:
 			if err := stack.GetStackInfo(); err != nil {
-				log.Fatal(err)
+				if err2 := rotateRoleCredentials(err); err2 != nil {
+					log.Fatal(err)
+				}
+				goto refresh_stack_status
 			}
 
 			printStackEvents(&stack, after)

commands/root.go

@@ -10,6 +10,7 @@ import (
 
 	forge "github.com/nathandines/forge/forgelib"
 
+	"github.com/aws/aws-sdk-go/aws/awserr"
 	"github.com/spf13/cobra"
 )
 
@@ -60,9 +61,13 @@ func Execute() {
 }
 
 func printStackEvents(s *forge.Stack, after *time.Time) {
+list_events:
 	bunch, err := s.ListEvents(after)
 	if err != nil {
-		log.Fatal(err)
+		if err2 := rotateRoleCredentials(err); err2 != nil {
+			log.Fatal(err)
+		}
+		goto list_events
 	}
 	for _, e := range bunch {
 		// IDs renamed for JSON output to match the API response data
@@ -91,3 +96,20 @@ func printStackEvents(s *forge.Stack, after *time.Time) {
 		*after = *bunch[len(bunch)-1].Timestamp
 	}
 }
+
+func rotateRoleCredentials(err error) error {
+	if awsErr, ok := err.(awserr.Error); ok && assumeRoleArn != "" {
+		switch awsErr.Code() {
+		case "ExpiredToken":
+			forge.UnassumeAllRoles()
+			if err2 := forge.AssumeRole(assumeRoleArn); err2 != nil {
+				return err
+			}
+		default:
+			return err
+		}
+	} else {
+		return err
+	}
+	return nil
+}

forgelib/auth.go

@@ -35,6 +35,7 @@ func AssumeRole(roleArn string) error {
 		return err
 	}
 	assumeOut, err := stsClient.AssumeRole(&sts.AssumeRoleInput{
+		DurationSeconds: aws.Int64(900),
 		RoleSessionName: aws.String(roleSessionName),
 		RoleArn:         aws.String(roleArn),
 	})