- add func ReplaceInFile

go.mod

@@ -1,3 +1,8 @@
 module github.com/ijustfool/docker-secrets
 
-require github.com/mitchellh/mapstructure v1.1.2
+require (
+	github.com/mitchellh/mapstructure v1.1.2
+	github.com/yosuke-furukawa/json5 v0.1.1
+)
+
+go 1.13

secrets.go

@@ -2,10 +2,12 @@ package secrets
 
 import (
 	"fmt"
+	"github.com/mitchellh/mapstructure"
 	"io/ioutil"
 	"os"
-
-	"github.com/mitchellh/mapstructure"
+	"path"
+	"regexp"
+	"strings"
 )
 
 // DockerSecrets contains secrets
@@ -49,6 +51,26 @@ func (ds *DockerSecrets) Unmarshal(output interface{}) error {
 	return decode(ds.secrets, defaultDecoderConfig(output))
 }
 
+// ReplaceInFile another way to get secrets from a config file
+func ReplaceInFile(b []byte) (result []byte, err error) {
+	var secretContent []byte
+	configContent := string(b)
+	re := regexp.MustCompile(`%docker-secret:([a-zA-Z0-9_\-\/]+)%`)
+	for _, captureGroups := range re.FindAllStringSubmatch(configContent, -1) {
+		dockerSecretSuggestion := captureGroups[0]
+		secretPath := captureGroups[1]
+		filePath := path.Join(secretPath)
+		secretContent, err = ioutil.ReadFile(filePath)
+		if err != nil {
+			return
+		}
+		dockerSecretValue := strings.TrimSpace(string(secretContent))
+		configContent = strings.ReplaceAll(configContent, dockerSecretSuggestion, dockerSecretValue)
+	}
+	result = []byte(configContent)
+	return
+}
+
 // defaultDecoderConfig returns default mapsstructure.DecoderConfig
 func defaultDecoderConfig(output interface{}) *mapstructure.DecoderConfig {
 	return &mapstructure.DecoderConfig{
@@ -99,7 +121,7 @@ func (ds *DockerSecrets) read(file string) error {
 	if err != nil {
 		return err
 	}
-	ds.secrets[file] = string(buf)
+	ds.secrets[file] = strings.TrimSpace(string(buf))
 	return nil
 }
 

secrets_test.go

@@ -1,6 +1,8 @@
 package secrets_test
 
 import (
+	"encoding/json"
+	"io/ioutil"
 	"testing"
 
 	"github.com/ijustfool/docker-secrets"
@@ -58,6 +60,34 @@ func TestDockerSecrets_Unmarshal(t *testing.T) {
 	}
 }
 
+func TestReplaceInFile(t *testing.T) {
+	b, err := ioutil.ReadFile(secretDir + "/config.json")
+	if err != nil {
+		t.Errorf("ReplaceInFile(): %v", err)
+		return
+	}
+
+	b, err = secrets.ReplaceInFile(b)
+	if err != nil {
+		t.Errorf("ReplaceInFile(): %v", err)
+		return
+	}
+
+	testSecrets := testSecrets{}
+	err = json.Unmarshal(b, &testSecrets)
+	if err != nil {
+		t.Errorf("ReplaceInFile(): %v", err)
+		return
+	}
+
+	if testSecrets.User != userVal {
+		t.Errorf("testSecrets.User = `%v`, expected: `%v`", testSecrets.User, userVal)
+	}
+	if testSecrets.Password != passVal {
+		t.Errorf("testSecrets.Password = `%v`, expected: `%v`", testSecrets.Password, passVal)
+	}
+}
+
 func checkKey(t *testing.T, dockerSecrets *secrets.DockerSecrets, key, expectedValue string) {
 	value, err := dockerSecrets.Get(key)
 	if err != nil {

test-data/config.json

@@ -0,0 +1,4 @@
+{
+  "user": "%docker-secret:test-data/user%",
+  "password": "%docker-secret:test-data/pass%"
+}