Support environmental variables in config.

CHANGES.txt

@@ -10,6 +10,8 @@ Bug Handling
 Features
 --------
 
+* Support environmental variables in config files (#1023)
+
 0.7.1 (2014-MM-DD)
 ==================
 

cmd/hekad/config.go

@@ -83,12 +83,20 @@ func LoadHekadConfig(configPath string) (config *HekadConfig, err error) {
 				continue
 			}
 			fPath := filepath.Join(configPath, fName)
-			if _, err = toml.DecodeFile(fPath, &configFile); err != nil {
+			contents, err := pipeline.ReplaceEnvsFile(fPath)
+			if err != nil {
+				return nil, err
+			}
+			if _, err = toml.Decode(contents, &configFile); err != nil {
 				return nil, fmt.Errorf("Error decoding config file: %s", err)
 			}
 		}
 	} else {
-		if _, err = toml.DecodeFile(configPath, &configFile); err != nil {
+		contents, err := pipeline.ReplaceEnvsFile(configPath)
+		if err != nil {
+			return nil, err
+		}
+		if _, err = toml.Decode(contents, &configFile); err != nil {
 			return nil, fmt.Errorf("Error decoding config file: %s", err)
 		}
 	}

docs/source/config/index.rst

@@ -218,6 +218,23 @@ Example hekad.toml file
 
 .. end-hekad-toml
 
+Using Environment Variables
+===========================
+
+If you wish to use environmental variables in your config files as a way to
+configure values, you can simply use ``$VARIABLE_NAME`` or ``${VARIABLE_NAME}``
+and the text will be replaced with the value of the environmental variable.
+
+Example:
+
+.. code-block:: ini
+
+    [AMQPInput]
+    url = "amqp://$USER:$PASSWORD@rabbitmq/"
+    exchange = "testout"
+    exchangeType = "fanout"
+
+
 .. start-restarting
 
 .. _configuring_restarting:

pipeline/config.go

@@ -20,6 +20,7 @@ import (
 	"code.google.com/p/go-uuid/uuid"
 	"fmt"
 	"github.com/bbangert/toml"
+	"io/ioutil"
 	"log"
 	"os"
 	"reflect"
@@ -814,7 +815,12 @@ const protobufEncoderToml = `
 func (self *PipelineConfig) LoadFromConfigFile(filename string) (err error) {
 	var configFile ConfigFile
 
-	if _, err = toml.DecodeFile(filename, &configFile); err != nil {
+	contents, err := ReplaceEnvsFile(filename)
+	if err != nil {
+		return err
+	}
+
+	if _, err = toml.Decode(contents, &configFile); err != nil {
 		return fmt.Errorf("Error decoding config file: %s", err)
 	}
 
@@ -960,3 +966,11 @@ func subsFromSection(section toml.Primitive) []string {
         }
         return subs
 }
+
+func ReplaceEnvsFile(path string) (string, error) {
+	contents, err := ioutil.ReadFile(path)
+	if err != nil {
+		return "", err
+	}
+	return os.ExpandEnv(string(contents)), nil
+}