1 files changed, 35 insertions, 32 deletions

diff --git a/src/org/traccar/Config.java b/src/org/traccar/Config.java
index 1be86fce0..c52c1bd81 100644
--- a/src/org/traccar/Config.java
+++ b/src/org/traccar/Config.java
@@ -23,40 +23,51 @@ import java.util.Properties;
 public class Config {
 
     private final Properties properties = new Properties();
-    private Properties defaultProperties;
 
-    public void load(String file) throws IOException {
-        try (InputStream inputStream = new FileInputStream(file)) {
-            properties.loadFromXML(inputStream);
-        }
+    private boolean useEnvVars = false;
 
+    void load(String file) throws IOException {
+        // First we load default config (if any)
         String defaultConfigFile = properties.getProperty("config.default");
         if (defaultConfigFile != null) {
             try (InputStream inputStream = new FileInputStream(defaultConfigFile)) {
-                defaultProperties = new Properties();
-                defaultProperties.loadFromXML(inputStream);
+                properties.loadFromXML(inputStream);
             }
         }
+        // Then we override by loading <code>file</code>
+        try (InputStream inputStream = new FileInputStream(file)) {
+            Properties props = new Properties();
+            props.loadFromXML(inputStream);
+            properties.putAll(props);
+        }
+        // Environment variables interpolation support
+        if ("true".equals(System.getenv("CONFIG_USE_ENV"))) {
+            useEnvVars = true;
+        } else {
+            useEnvVars = properties.getProperty("config.useEnv", "false").equalsIgnoreCase("true");
+        }
     }
 
+
     public boolean hasKey(String key) {
-        return properties.containsKey(key) || defaultProperties != null && defaultProperties.containsKey(key);
+        if (useEnvVars && System.getenv().containsKey(getEnvVarName(key))) {
+            return true;
+        }
+        return properties.containsKey(key);
     }
 
     public String getString(String key) {
-        if (properties.containsKey(key) || defaultProperties == null) {
-            return properties.getProperty(key);
-        } else {
-            return defaultProperties.getProperty(key);
+        if (useEnvVars) {
+            String envValue = System.getenv(getEnvVarName(key));
+            if (envValue != null && !envValue.isEmpty()) {
+                return envValue;
+            }
         }
+        return properties.getProperty(key);
     }
 
     public String getString(String key, String defaultValue) {
-        if (hasKey(key)) {
-            return getString(key);
-        } else {
-            return defaultValue;
-        }
+        return hasKey(key) ? getString(key) : defaultValue;
     }
 
     public boolean getBoolean(String key) {
@@ -68,11 +79,7 @@ public class Config {
     }
 
     public int getInteger(String key, int defaultValue) {
-        if (hasKey(key)) {
-            return Integer.parseInt(getString(key));
-        } else {
-            return defaultValue;
-        }
+        return hasKey(key) ? Integer.parseInt(getString(key)) : defaultValue;
     }
 
     public long getLong(String key) {
@@ -80,11 +87,7 @@ public class Config {
     }
 
     public long getLong(String key, long defaultValue) {
-        if (hasKey(key)) {
-            return Long.parseLong(getString(key));
-        } else {
-            return defaultValue;
-        }
+        return hasKey(key) ? Long.parseLong(getString(key)) : defaultValue;
     }
 
     public double getDouble(String key) {
@@ -92,11 +95,11 @@ public class Config {
     }
 
     public double getDouble(String key, double defaultValue) {
-        if (hasKey(key)) {
-            return Double.parseDouble(getString(key));
-        } else {
-            return defaultValue;
-        }
+        return hasKey(key) ? Double.parseDouble(getString(key)) : defaultValue;
+    }
+
+    public static String getEnvVarName(String key) {
+        return key.replaceAll("\\.", "_").replaceAll("(.)(\\p{Lu})", "$1_$2").toUpperCase();
     }
 
 }