Fix addkey error messages and improve usability

cmd/envelope/add_key.go

@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"net/url"
 
-	errors "github.com/hashicorp/errwrap"
+	"github.com/ansel1/merry"
 	"github.com/mikesimons/envelope"
 	"gopkg.in/urfave/cli.v1"
 )
@@ -13,8 +13,10 @@ import (
 // e.g $ envelope add-key test kms://arn
 func addKeyCommand() cli.Command {
 	return cli.Command{
-		Name:      "add-key",
-		Usage:     "Add a key to the keyring",
+		Name:  "addkey",
+		Usage: "Add a key to the keyring.",
+		Description: `Master key DSN is of the form <provider>://<dsn>. The only supported provider is currently awskms.
+   Example: envelope add-key mytestkey awskms://arn:aws:kms:us-east-1:111111111111:key/abcdef01-2345-6789-abcd-ef0123456789`,
 		ArgsUsage: "<alias> <master key dsn>",
 		Flags: []cli.Flag{
 			cli.StringFlag{
@@ -24,7 +26,7 @@ func addKeyCommand() cli.Command {
 		},
 		Action: func(c *cli.Context) error {
 			if c.NArg() != 2 {
-				cli.ShowCommandHelp(c, "add-key")
+				cli.ShowCommandHelp(c, "addkey")
 				fmt.Println("")
 				return cli.NewExitError("Error: Not enough arguments", 1)
 			}
@@ -61,7 +63,7 @@ func parseEncryptionContext(input string) (map[string]string, error) {
 
 	values, err := url.ParseQuery(input)
 	if err != nil {
-		return nil, errors.Wrapf("Unable to parse encryption context", err)
+		return nil, merry.Wrap(err).WithMessage("Unable to parse encryption context")
 	}
 
 	output := make(map[string]string)

cmd/envelope/shared.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 
 	"github.com/ansel1/merry"
+	cli "gopkg.in/urfave/cli.v1"
 )
 
 func asFormat(as string, input string) string {
@@ -66,7 +67,7 @@ func processErrors(err error) error {
 	}
 	lines = append(lines, strings.Join(extra, ", "))
 
-	return fmt.Errorf(strings.Join(lines, "\n"))
+	return cli.NewExitError(strings.Join(lines, "\n"), 1)
 }
 
 func getInputReader(input string) (io.Reader, error) {

keysvc/keysvc.go

@@ -3,6 +3,7 @@ package keysvc
 import (
 	"fmt"
 	"net/url"
+	"strings"
 
 	"github.com/ansel1/merry"
 	"github.com/mikesimons/envelope/keysvc/awskms"
@@ -26,7 +27,11 @@ func GetKeyService(name string) (KeyServiceProvider, error) {
 		return fn()
 	}
 
-	return nil, fmt.Errorf("Unknown key service: %s", name)
+	var known []string
+	for k := range services {
+		known = append(known, k)
+	}
+	return nil, merry.Errorf("Unknown key service. Must be one of: %s", strings.Join(known, ", ")).WithValue("svc", name)
 }
 
 func GenerateDatakey(alias string, masterKey string, context map[string]string) (*Key, error) {