diff --git a/README.md b/README.md
index b211119..04ce29f 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,6 @@ up a ready-to-roll mongodb or openldap server, it does what it is supposed to.
 
 ## Todo
 
-- [ ] Add a --temporary option to start to remove volume after stop
 - [x] Rename from `serverctl` to `server`
 - [x] Implement variables in environment section
 - [x] Provide environment, ex. `${SERVER_HOST}` for docker host IP
@@ -16,6 +15,7 @@ up a ready-to-roll mongodb or openldap server, it does what it is supposed to.
 - [ ] App port binding, i.e. phpmyadmin on 9000, phpcacheadmin on 9001
 - [ ] Make use of a `~/.serverenvs` to override envs for instances
 - [x] Consider UDP?
+- [ ] Fix the service scripts implementation
 
 ## Examples
 
@@ -86,12 +86,26 @@ the project root when running from source.
 }
 ```
 
+## Permanently customizing instances
+
+To customize an instance, create the file `~/.serverenvs` if it doesn't exist
+and open in a text editor. The definitions for each instance is contained in
+a section named after the server and the instance name separated by a colon:
+
+```
+[mysql:backups]
+MYSQL_ROOT_PASSWORD=something
+
+[server:instance]
+ENV_VAR=value
+```
 
 ## FAQ
 
 ### Where is the data stored?
 
-* Data goes in `$HOME/.var/serverctl`
+Data goes in `$HOME/.var/serverctl`. As volumes are generally not owned by your
+user, you will have to manually delete old instances.
 
 ### How can I tell a container to connect to another container?
 
diff --git a/src/Container/ContainerManager.php b/src/Container/ContainerManager.php
index 378ac7d..341c639 100644
--- a/src/Container/ContainerManager.php
+++ b/src/Container/ContainerManager.php
@@ -13,11 +13,28 @@ class ContainerManager
 
     private array $autoEnv = [];
 
+    private array $serverEnvs = [];
+
     public function __construct(?string $dataPath=null)
     {
         $this->dataPath = $dataPath ?? (getenv("HOME")."/.var/serverctl");
         $this->stateFile = $this->dataPath . "/state.json";
         $this->setupAutoEnv();
+        $this->setupServerEnvs();
+    }
+
+    private function setupServerEnvs()
+    {
+        $file = getenv("HOME")."/.serverenvs";
+
+        if (!file_exists($file)) {
+            $this->serverEnvs = [];
+            return;
+        }
+
+        $parsed = parse_ini_file($file, true);
+
+        $this->serverEnvs = $parsed;
     }
 
     private function setupAutoEnv()
@@ -105,6 +122,11 @@ class ContainerManager
         $instanceName = $options['name']??'default';
         $portOffset = intval($options['portoffset']??0);
 
+        $temporary = $option['temporary']??false;
+        if ($temporary) {
+            $instanceName = sprintf("%04x%04x", rand(0,0xFFFF), rand(0,0xFFFF));
+        }
+
         $containerName = "sm_".$serviceName."_".$instanceName;
 
         $args[] = 'run';
@@ -136,10 +158,22 @@ class ContainerManager
             $args[] = $volumePath."/".$hint.":".$path;
         }
 
+        $parsedEnv = [];
+
+        // Prepared environment from serviceenvs
+        $key = $serviceName . ":" . $instanceName;
+        if (array_key_exists($key, $this->serverEnvs)) {
+            foreach ($this->serverEnvs[$key] as $env=>$value) {
+                $value = $this->expandString($value);
+                array_push($args, "-e", sprintf("%s=%s", $env, $value));
+                $parsedEnv[$env] = $value;
+            }
+        }
+
         // Get environment
         $envs = (array)($service['environment']??[]);
-        $parsedEnv = [];
         foreach ($envs as $env=>$value) {
+            if (array_key_exists($env, $parsedEnv)) continue;
             $args[] = '-e';
             $envval = getenv($env, true);
             if ($envval) $value = $envval;
@@ -153,6 +187,7 @@ class ContainerManager
         $cmdl = 'docker '.join(' ',array_map('escapeshellarg', $args));
         
         //echo "$ {$cmdl}\n";
+
         exec($cmdl, $out, $ret);
         if ($ret != 0) {
             echo join("\n",$out)."\n";
@@ -164,7 +199,8 @@ class ContainerManager
             'instance' => $instanceName,
             'environment' => $parsedEnv,
             'service' => $service,
-            'ports' => $mappedPorts
+            'ports' => $mappedPorts,
+            'temporary' => $temporary,
         ]);
 
         return [