diff --git a/src/main/java/JettyLauncher.java b/src/main/java/JettyLauncher.java
index 8b91e91..94525fd 100644
--- a/src/main/java/JettyLauncher.java
+++ b/src/main/java/JettyLauncher.java
@@ -134,17 +134,6 @@
         return new File(System.getProperty("user.home"), ".gitbucket");
     }
 
-    private static void deleteDirectory(File dir){
-        for(File file: dir.listFiles()){
-            if(file.isFile()){
-                file.delete();
-            } else if(file.isDirectory()){
-                deleteDirectory(file);
-            }
-        }
-        dir.delete();
-    }
-
     private static Handler addStatisticsHandler(Handler handler) {
         // The graceful shutdown is implemented via the statistics handler.
         // See the following: https://bugs.eclipse.org/bugs/show_bug.cgi?id=420142
diff --git a/src/main/scala/gitbucket/core/service/SystemSettingsService.scala b/src/main/scala/gitbucket/core/service/SystemSettingsService.scala
index 1647cba..248d122 100644
--- a/src/main/scala/gitbucket/core/service/SystemSettingsService.scala
+++ b/src/main/scala/gitbucket/core/service/SystemSettingsService.scala
@@ -1,9 +1,9 @@
 package gitbucket.core.service
 
-import gitbucket.core.util.{Directory, SyntaxSugars}
 import gitbucket.core.util.Implicits._
-import Directory._
-import SyntaxSugars._
+import gitbucket.core.util.ConfigUtil._
+import gitbucket.core.util.Directory._
+import gitbucket.core.util.SyntaxSugars._
 import SystemSettingsService._
 import javax.servlet.http.HttpServletRequest
 
@@ -220,23 +220,28 @@
   private val LdapSsl = "ldap.ssl"
   private val LdapKeystore = "ldap.keystore"
 
-  private def getValue[A: ClassTag](props: java.util.Properties, key: String, default: A): A =
-    defining(props.getProperty(key)){ value =>
-      if(value == null || value.isEmpty) default
-      else convertType(value).asInstanceOf[A]
-    }
+  private def getValue[A: ClassTag](props: java.util.Properties, key: String, default: A): A = {
+    getSystemProperty(key).getOrElse(getEnvironmentVariable(key).getOrElse {
+      defining(props.getProperty(key)){ value =>
+        if(value == null || value.isEmpty){
+          default
+        } else {
+          convertType(value).asInstanceOf[A]
+        }
+      }
+    })
+  }
 
-  private def getOptionValue[A: ClassTag](props: java.util.Properties, key: String, default: Option[A]): Option[A] =
-    defining(props.getProperty(key)){ value =>
-      if(value == null || value.isEmpty) default
-      else Some(convertType(value)).asInstanceOf[Option[A]]
-    }
-
-  private def convertType[A: ClassTag](value: String) =
-    defining(implicitly[ClassTag[A]].runtimeClass){ c =>
-      if(c == classOf[Boolean])  value.toBoolean
-      else if(c == classOf[Int]) value.toInt
-      else value
-    }
+  private def getOptionValue[A: ClassTag](props: java.util.Properties, key: String, default: Option[A]): Option[A] = {
+    getSystemProperty(key).orElse(getEnvironmentVariable(key).orElse {
+      defining(props.getProperty(key)){ value =>
+        if(value == null || value.isEmpty){
+          default
+        } else {
+          Some(convertType(value)).asInstanceOf[Option[A]]
+        }
+      }
+    })
+  }
 
 }
diff --git a/src/main/scala/gitbucket/core/util/DatabaseConfig.scala b/src/main/scala/gitbucket/core/util/DatabaseConfig.scala
index 644c3f2..072b583 100644
--- a/src/main/scala/gitbucket/core/util/DatabaseConfig.scala
+++ b/src/main/scala/gitbucket/core/util/DatabaseConfig.scala
@@ -4,11 +4,15 @@
 import java.io.File
 
 import Directory._
-import com.github.takezoe.slick.blocking.{BlockingH2Driver, BlockingMySQLDriver, BlockingJdbcProfile}
+import ConfigUtil._
+import com.github.takezoe.slick.blocking.{BlockingH2Driver, BlockingJdbcProfile, BlockingMySQLDriver}
+import gitbucket.core.util.SyntaxSugars.defining
 import liquibase.database.AbstractJdbcDatabase
 import liquibase.database.core.{H2Database, MySQLDatabase, PostgresDatabase}
 import org.apache.commons.io.FileUtils
 
+import scala.reflect.ClassTag
+
 object DatabaseConfig {
 
   private lazy val config = {
@@ -30,14 +34,14 @@
     ConfigFactory.parseFile(file)
   }
 
-  private lazy val dbUrl = config.getString("db.url")
+  private lazy val dbUrl = getValue("db.url", config.getString) //config.getString("db.url")
 
   def url(directory: Option[String]): String =
     dbUrl.replace("${DatabaseHome}", directory.getOrElse(DatabaseHome))
 
   lazy val url                : String = url(None)
-  lazy val user               : String = config.getString("db.user")
-  lazy val password           : String = config.getString("db.password")
+  lazy val user               : String = getValue("db.user", config.getString)
+  lazy val password           : String = getValue("db.password", config.getString)
   lazy val jdbcDriver         : String = DatabaseType(url).jdbcDriver
   lazy val slickDriver        : BlockingJdbcProfile  = DatabaseType(url).slickDriver
   lazy val liquiDriver        : AbstractJdbcDatabase = DatabaseType(url).liquiDriver
@@ -47,8 +51,16 @@
   lazy val minimumIdle        : Option[Int]    = getOptionValue("db.minimumIdle"      , config.getInt)
   lazy val maximumPoolSize    : Option[Int]    = getOptionValue("db.maximumPoolSize"  , config.getInt)
 
+  private def getValue[T](path: String, f: String => T): T = {
+    getSystemProperty(path).getOrElse(getEnvironmentVariable(path).getOrElse{
+      f(path)
+    })
+  }
+
   private def getOptionValue[T](path: String, f: String => T): Option[T] = {
-    if(config.hasPath(path)) Some(f(path)) else None
+    getSystemProperty(path).orElse(getEnvironmentVariable(path).orElse {
+      if(config.hasPath(path)) Some(f(path)) else None
+    })
   }
 
 }
@@ -99,3 +111,33 @@
     }
   }
 }
+
+object ConfigUtil {
+
+  def getEnvironmentVariable[A](key: String): Option[A] = {
+    val value = System.getenv("GITBUCKET_" + key.toUpperCase.replace('.', '_'))
+    if(value != null && value.nonEmpty){
+      Some(convertType(value)).asInstanceOf[Option[A]]
+    } else {
+      None
+    }
+  }
+
+  def getSystemProperty[A](key: String): Option[A] = {
+    val value = System.getProperty("gitbucket." + key)
+    if(value != null && value.nonEmpty){
+      Some(convertType(value)).asInstanceOf[Option[A]]
+    } else {
+      None
+    }
+  }
+
+  def convertType[A: ClassTag](value: String) =
+    defining(implicitly[ClassTag[A]].runtimeClass){ c =>
+      if(c == classOf[Boolean])  value.toBoolean
+      else if(c == classOf[Long]) value.toLong
+      else if(c == classOf[Int]) value.toInt
+      else value
+    }
+
+}