Implement plain parameters.

Fixes #4

README.md

@@ -14,7 +14,7 @@ All parameters must be in JSON format, i.e.:
     }
 ```
 
-If a few parameters are specified, all JSON entities will be read and merged into one, overriding existing keys, i.e.
+If several parameters are specified, all JSON entities will be read and merged into one, overriding existing keys, i.e.
 
 Parameter one:
 ```
@@ -39,6 +39,10 @@ The result will be merged as this:
     }
 ```
 
+One can also specify `--plain-name` and `--plain-path` command line options to read _plain_ parameters that are not in JSON format.
+`ssm-parent` takes the value as is, and constructs a key name from the `basename parameter`,
+ i.e. a SSM Parameter `/project/environment/myParameter` with value `supervalue` will be exported as `myParameter=supervalue`.
+
 ### How to use
 
 
@@ -48,7 +52,10 @@ That should be pretty self-explanatory.
 SSM-Parent is a docker entrypoint.
 
 It gets specified parameters (possibly secret) from AWS SSM Parameter Store,
-then exports them to the underlying process.
+then exports them to the underlying process. Or creates a .env file to be consumed by an application.
+
+It reads parameters in the following order: path->name->plain-path->plain-name.
+So that every rightmost parameter overrides the previous one.
 
 Usage:
   ssm-parent [command]
@@ -60,12 +67,15 @@ Available Commands:
   run         Runs the specified command
 
 Flags:
-  -e, --expand             Expand arguments and values using shell-style syntax
-  -h, --help               help for ssm-parent
-  -n, --name stringArray   Name of the SSM parameter to retrieve. Can be specified multiple times.
-  -p, --path stringArray   Path to a SSM parameter. Can be specified multiple times.
-  -r, --recursive          Walk through the provided SSM paths recursively.
-  -s, --strict             Strict mode. Fail if found less parameters than number of names.
+  -e, --expand                   Expand arguments and values using shell-style syntax
+  -h, --help                     help for ssm-parent
+  -n, --name stringArray         Name of the SSM parameter to retrieve. Expects JSON in the value. Can be specified multiple times.
+  -p, --path stringArray         Path to a SSM parameter. Expects JSON in the value. Can be specified multiple times.
+      --plain-name stringArray   Name of the SSM parameter to retrieve. Expects actual parameter in the value. Can be specified multiple times.
+      --plain-path stringArray   Path to a SSM parameter. Expects actual parameter in the value. Can be specified multiple times.
+  -r, --recursive                Walk through the provided SSM paths recursively.
+  -s, --strict                   Strict mode. Fail if found less parameters than number of names.
+      --version                  version for ssm-parent
 
 Use "ssm-parent [command] --help" for more information about a command.
 ```

cmd/dotenv.go

@@ -16,7 +16,7 @@ var dotenvCmd = &cobra.Command{
 	Args:  cobra.ExactArgs(1),
 	Run: func(cmd *cobra.Command, args []string) {
 		megamap := make(map[string]string)
-		parameters, err := ssm.GetParameters(names, paths, expand, strict, recursive)
+		parameters, err := ssm.GetParameters(names, paths, plainNames, plainPaths, expand, strict, recursive)
 		if err != nil {
 			log.WithError(err).Fatal("Can't get parameters")
 		}

cmd/print.go

@@ -17,7 +17,7 @@ var printCmd = &cobra.Command{
 	Run: func(cmd *cobra.Command, args []string) {
 
 		megamap := make(map[string]string)
-		parameters, err := ssm.GetParameters(names, paths, expand, strict, recursive)
+		parameters, err := ssm.GetParameters(names, paths, plainNames, plainPaths, expand, strict, recursive)
 		if err != nil {
 			log.WithError(err).Fatal("Can't get parameters")
 		}

cmd/root.go

@@ -8,11 +8,13 @@ import (
 )
 
 var (
-	paths     []string
-	names     []string
-	recursive bool
-	strict    bool
-	expand    bool
+	paths      []string
+	names      []string
+	plainPaths []string
+	plainNames []string
+	recursive  bool
+	strict     bool
+	expand     bool
 )
 
 // rootCmd represents the base command when called without any subcommands
@@ -22,7 +24,10 @@ var rootCmd = &cobra.Command{
 	Long: `SSM-Parent is a docker entrypoint.
 	
 It gets specified parameters (possibly secret) from AWS SSM Parameter Store,
-then exports them to the underlying process.
+then exports them to the underlying process. Or creates a .env file to be consumed by an application.
+
+It reads parameters in the following order: path->name->plain-path->plain-name.
+So that every rightmost parameter overrides the previous one.
 `,
 }
 
@@ -35,8 +40,10 @@ func Execute(version string) {
 }
 
 func init() {
-	rootCmd.PersistentFlags().StringArrayVarP(&paths, "path", "p", []string{}, "Path to a SSM parameter. Can be specified multiple times.")
-	rootCmd.PersistentFlags().StringArrayVarP(&names, "name", "n", []string{}, "Name of the SSM parameter to retrieve. Can be specified multiple times.")
+	rootCmd.PersistentFlags().StringArrayVarP(&paths, "path", "p", []string{}, "Path to a SSM parameter. Expects JSON in the value. Can be specified multiple times.")
+	rootCmd.PersistentFlags().StringArrayVarP(&names, "name", "n", []string{}, "Name of the SSM parameter to retrieve. Expects JSON in the value. Can be specified multiple times.")
+	rootCmd.PersistentFlags().StringArrayVarP(&plainPaths, "plain-path", "", []string{}, "Path to a SSM parameter. Expects actual parameter in the value. Can be specified multiple times.")
+	rootCmd.PersistentFlags().StringArrayVarP(&plainNames, "plain-name", "", []string{}, "Name of the SSM parameter to retrieve. Expects actual parameter in the value. 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 shell-style syntax")

cmd/run.go

@@ -21,7 +21,7 @@ var runCmd = &cobra.Command{
 		var cmdArgs []string
 
 		megamap := make(map[string]string)
-		parameters, err := ssm.GetParameters(names, paths, expand, strict, recursive)
+		parameters, err := ssm.GetParameters(names, paths, plainNames, plainPaths, expand, strict, recursive)
 		if err != nil {
 			log.WithError(err).Fatal("Can't get parameters")
 		}

ssm/parameters.go

@@ -3,6 +3,7 @@ package ssm
 import (
 	"encoding/json"
 	"fmt"
+	goPath "path"
 
 	"github.com/apex/log"
 	"github.com/aws/aws-sdk-go/aws"
@@ -57,6 +58,30 @@ func getJsonSSMParametersByPaths(paths []string, strict, recursive bool) (parame
 	return
 }
 
+func getPlainSSMParametersByPaths(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
+	}
+	s := ssm.New(localSession)
+	for _, path := range paths {
+		response, innerErr := s.GetParametersByPath(&ssm.GetParametersByPathInput{
+			Path:           aws.String(path),
+			WithDecryption: aws.Bool(true),
+			Recursive:      aws.Bool(recursive),
+		})
+		if innerErr != nil {
+			err = multierror.Append(err, fmt.Errorf("Can't get parameters from path '%s': %s", path, innerErr))
+		}
+		for _, parameter := range response.Parameters {
+			values := make(map[string]string)
+			values[goPath.Base(aws.StringValue(parameter.Name))] = aws.StringValue(parameter.Value)
+			parameters = append(parameters, values)
+		}
+	}
+	return
+}
+
 func getJsonSSMParameters(names []string, strict bool) (parameters []map[string]string, err error) {
 	err = makeSession()
 	if err != nil {
@@ -93,13 +118,51 @@ func getJsonSSMParameters(names []string, strict bool) (parameters []map[string]
 	return
 }
 
-func GetParameters(names, paths []string, expand, strict, recursive bool) (parameters []map[string]string, err error) {
+func getPlainSSMParameters(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
+	}
+	s := ssm.New(localSession)
+	response, err := s.GetParameters(&ssm.GetParametersInput{
+		Names:          aws.StringSlice(names),
+		WithDecryption: aws.Bool(true),
+	})
+	if err != nil {
+		return nil, err
+	}
+	if len(response.Parameters) < len(names) {
+		if strict {
+			err = multierror.Append(err, fmt.Errorf("Found %d parameters from %d names", len(response.Parameters), len(names)))
+		} else {
+			var found []string
+			for _, f := range response.Parameters {
+				found = append(found, *f.Name)
+			}
+			diff := stringSliceDifference(names, found)
+			log.WithFields(log.Fields{"missing_names": diff}).Warn("Some parameters have not been found")
+		}
+	}
+	for _, parameter := range response.Parameters {
+		values := make(map[string]string)
+		values[goPath.Base(aws.StringValue(parameter.Name))] = aws.StringValue(parameter.Value)
+		parameters = append(parameters, values)
+	}
+	return
+}
+
+func GetParameters(names, paths, plainNames, plainPaths []string, expand, strict, recursive bool) (parameters []map[string]string, err error) {
 	localNames := names
 	localPaths := paths
+	localPlainNames := plainNames
+	localPlainPaths := plainPaths
 	if expand {
 		localNames = ExpandArgs(names)
 		localPaths = ExpandArgs(paths)
+		localPlainNames = ExpandArgs(plainNames)
+		localPlainPaths = ExpandArgs(plainPaths)
 	}
+
 	if len(localPaths) > 0 {
 		parametersFromPaths, err := getJsonSSMParametersByPaths(localPaths, strict, recursive)
 		if err != nil {
@@ -122,5 +185,28 @@ func GetParameters(names, paths []string, expand, strict, recursive bool) (param
 			parameters = append(parameters, parameter)
 		}
 	}
+	if len(localPlainPaths) > 0 {
+		parametersFromPlainPaths, err := getPlainSSMParametersByPaths(localPlainPaths, strict, recursive)
+		if err != nil {
+			log.WithError(err).WithFields(
+				log.Fields{"plain_paths": localPaths},
+			).Fatal("Can't get plain parameters by paths")
+		}
+		for _, parameter := range parametersFromPlainPaths {
+			parameters = append(parameters, parameter)
+		}
+	}
+
+	if len(localPlainNames) > 0 {
+		parametersFromPlainNames, err := getPlainSSMParameters(localPlainNames, strict)
+		if err != nil {
+			log.WithError(err).WithFields(
+				log.Fields{"plain_names": localNames},
+			).Fatal("Can't get plain parameters by names")
+		}
+		for _, parameter := range parametersFromPlainNames {
+			parameters = append(parameters, parameter)
+		}
+	}
 	return
 }