Change interpolation engine from sh to native

Enable args expansion for `print` command.

cmd/print.go

@@ -16,8 +16,8 @@ var printCmd = &cobra.Command{
 	Short: "Prints the specified parameters.",
 	Run: func(cmd *cobra.Command, args []string) {
 
-		megamap := make(map[string]interface{})
-		parameters, err := ssm.GetParameters(names, paths, strict, recursive)
+		megamap := make(map[string]string)
+		parameters, err := ssm.GetParameters(names, paths, expand, strict, recursive)
 		if err != nil {
 			log.WithError(err).Fatal("Can't get parameters")
 		}
@@ -27,6 +27,11 @@ var printCmd = &cobra.Command{
 				log.WithError(err).Fatal("Can't merge maps")
 			}
 		}
+		for key, value := range megamap {
+			if expand {
+				megamap[key] = ssm.ExpandValue(value)
+			}
+		}
 		marshalled, err := json.MarshalIndent(megamap, "", "  ")
 		if err != nil {
 			log.WithError(err).Fatal("Can't marshal json")

cmd/root.go

@@ -12,6 +12,7 @@ var (
 	names     []string
 	recursive bool
 	strict    bool
+	expand    bool
 )
 
 // rootCmd represents the base command when called without any subcommands
@@ -38,4 +39,5 @@ func init() {
 	rootCmd.PersistentFlags().StringArrayVarP(&names, "name", "n", []string{}, "Name of the SSM parameter to retrieve. Can be specified multiple times.")
 	rootCmd.PersistentFlags().BoolVarP(&recursive, "recursive", "r", false, "Walk through the provided SSM paths recursively.")
 	rootCmd.PersistentFlags().BoolVarP(&strict, "strict", "s", false, "Strict mode. Fail if found less parameters than number of names.")
+	rootCmd.PersistentFlags().BoolVarP(&expand, "expand", "e", false, "Expand arguments and values using /bin/sh")
 }

cmd/run.go

@@ -1,11 +1,9 @@
 package cmd
 
 import (
-	"fmt"
 	"os"
 	"os/exec"
 	"os/signal"
-	"strings"
 
 	"github.com/springload/ssm-parent/ssm"
 
@@ -14,8 +12,6 @@ import (
 	"github.com/spf13/cobra"
 )
 
-var expand bool
-
 // runCmd represents the run command
 var runCmd = &cobra.Command{
 	Use:   "run command",
@@ -24,14 +20,8 @@ var runCmd = &cobra.Command{
 	Run: func(cobraCmd *cobra.Command, args []string) {
 		var cmdArgs []string
 
-		megamap := make(map[string]interface{})
-		localNames := names
-		localPaths := paths
-		if expand {
-			localNames = expandArgs(names)
-			localPaths = expandArgs(paths)
-		}
-		parameters, err := ssm.GetParameters(localNames, localPaths, strict, recursive)
+		megamap := make(map[string]string)
+		parameters, err := ssm.GetParameters(names, paths, expand, strict, recursive)
 		if err != nil {
 			log.WithError(err).Fatal("Can't get parameters")
 		}
@@ -43,11 +33,9 @@ var runCmd = &cobra.Command{
 		}
 		for key, value := range megamap {
 			if expand {
-				if stringValue, ok := value.(string); ok {
-					value = expandValue(stringValue)
-				}
+				value = ssm.ExpandValue(value)
 			}
-			os.Setenv(key, fmt.Sprintf("%v", value))
+			os.Setenv(key, value)
 		}
 
 		command, err := exec.LookPath(args[0])
@@ -59,7 +47,7 @@ var runCmd = &cobra.Command{
 		c := make(chan os.Signal, 1)
 		signal.Notify(c)
 		if expand {
-			cmdArgs = expandArgs(args[1:])
+			cmdArgs = ssm.ExpandArgs(args[1:])
 		} else {
 			cmdArgs = args[1:]
 		}
@@ -86,31 +74,6 @@ var runCmd = &cobra.Command{
 	},
 }
 
-// expandArgs leverages on shell and echo to expand
-// possible args mainly env vars.
-// taken from https://github.com/abiosoft/parent
-func expandArgs(args []string) []string {
-	var expanded []string
-	for _, arg := range args {
-		arg = expandValue(arg)
-		expanded = append(expanded, arg)
-	}
-	return expanded
-}
-
-func expandValue(val string) string {
-	e, err := exec.Command("/bin/sh", "-c", fmt.Sprintf("echo %s", val)).Output()
-	// error is not expected.
-	// in the rare case that this errors
-	// the original arg is still used.
-	if err == nil {
-		return strings.TrimSpace(string(e))
-	}
-	return val
-
-}
-
 func init() {
-	runCmd.Flags().BoolVarP(&expand, "expand", "e", false, "Expand arguments and values using /bin/sh")
 	rootCmd.AddCommand(runCmd)
 }

ssm/parameters.go

@@ -30,7 +30,7 @@ func makeSession() error {
 	return nil
 }
 
-func getJsonSSMParametersByPaths(paths []string, strict, recursive bool) (parameters []map[string]interface{}, err error) {
+func getJsonSSMParametersByPaths(paths []string, strict, recursive bool) (parameters []map[string]string, err error) {
 	err = makeSession()
 	if err != nil {
 		log.WithError(err).Fatal("Can't create session") // fail early here
@@ -46,7 +46,7 @@ func getJsonSSMParametersByPaths(paths []string, strict, recursive bool) (parame
 			err = multierror.Append(err, fmt.Errorf("Can't get parameters from path '%s': %s", path, innerErr))
 		}
 		for _, parameter := range response.Parameters {
-			value := make(map[string]interface{})
+			value := make(map[string]string)
 			innerErr := json.Unmarshal([]byte(*parameter.Value), &value)
 			if innerErr != nil {
 				err = multierror.Append(err, fmt.Errorf("Can't unmarshal json from '%s': %s", *parameter.Name, innerErr))
@@ -57,7 +57,7 @@ func getJsonSSMParametersByPaths(paths []string, strict, recursive bool) (parame
 	return
 }
 
-func getJsonSSMParameters(names []string, strict bool) (parameters []map[string]interface{}, err error) {
+func getJsonSSMParameters(names []string, strict bool) (parameters []map[string]string, err error) {
 	err = makeSession()
 	if err != nil {
 		log.WithError(err).Fatal("Can't create session") // fail early here
@@ -83,7 +83,7 @@ func getJsonSSMParameters(names []string, strict bool) (parameters []map[string]
 		}
 	}
 	for _, parameter := range response.Parameters {
-		value := make(map[string]interface{})
+		value := make(map[string]string)
 		innerErr := json.Unmarshal([]byte(*parameter.Value), &value)
 		if innerErr != nil {
 			err = multierror.Append(err, fmt.Errorf("Can't unmarshal json from '%s': %s", *parameter.Name, innerErr))
@@ -93,23 +93,29 @@ func getJsonSSMParameters(names []string, strict bool) (parameters []map[string]
 	return
 }
 
-func GetParameters(names, paths []string, strict, recursive bool) (parameters []map[string]interface{}, err error) {
-	if len(names) > 0 {
-		parametersFromNames, err := getJsonSSMParameters(names, strict)
+func GetParameters(names, paths []string, expand, strict, recursive bool) (parameters []map[string]string, err error) {
+	localNames := names
+	localPaths := paths
+	if expand {
+		localNames = ExpandArgs(names)
+		localPaths = ExpandArgs(paths)
+	}
+	if len(localNames) > 0 {
+		parametersFromNames, err := getJsonSSMParameters(localNames, strict)
 		if err != nil {
 			log.WithError(err).WithFields(
-				log.Fields{"names": names},
+				log.Fields{"names": localNames},
 			).Fatal("Can't get parameters by names")
 		}
 		for _, parameter := range parametersFromNames {
 			parameters = append(parameters, parameter)
 		}
 	}
-	if len(paths) > 0 {
-		parametersFromPaths, err := getJsonSSMParametersByPaths(paths, strict, recursive)
+	if len(localPaths) > 0 {
+		parametersFromPaths, err := getJsonSSMParametersByPaths(localPaths, strict, recursive)
 		if err != nil {
 			log.WithError(err).WithFields(
-				log.Fields{"paths": paths},
+				log.Fields{"paths": localPaths},
 			).Fatal("Can't get parameters by paths")
 		}
 		for _, parameter := range parametersFromPaths {

ssm/util.go

@@ -1,5 +1,14 @@
 package ssm
 
+import (
+	"os"
+	"strings"
+
+	"github.com/buildkite/interpolate"
+)
+
+var env Env
+
 // difference returns the elements in a that aren't in b
 // the second argument is slice of string pointers to suit AWS SDK
 func stringSliceDifference(a, b []string) []string {
@@ -15,3 +24,27 @@ func stringSliceDifference(a, b []string) []string {
 	}
 	return ab
 }
+
+func ExpandArgs(args []string) []string {
+	var expanded []string
+	for _, arg := range args {
+		arg = ExpandValue(arg)
+		expanded = append(expanded, arg)
+	}
+	return expanded
+}
+func ExpandValue(val string) string {
+	e, err := interpolate.Interpolate(env, val)
+	if err == nil {
+		return strings.TrimSpace(string(e))
+	}
+	return val
+
+}
+
+// just adapt os.LookupEnv to this interface
+type Env struct{}
+
+func (e Env) Get(key string) (string, bool) {
+	return os.LookupEnv(key)
+}