Add prepend config option

README.md

@@ -76,6 +76,16 @@ config:
       - another-excluded-func
 ```
 
+#### `prepend` (optional)
+
+Whether or not to prepend the IOpipe layer. Defaults to `false` which appends the layer.
+
+```yaml
+config:
+  iopipe:
+    prepend: true
+```
+
 
 ## Supported Runtimes
 

src/index.ts

@@ -109,7 +109,11 @@ export default class IOpipeLayerPlugin {
         `Function "${funcName}" already specifies an IOpipe layer; skipping.`
       );
     } else {
-      layers.push(layerArn);
+      if (typeof this.config.prepend === "boolean" && this.config.prepend) {
+        layers.unshift(layerArn);
+      } else {
+        layers.push(layerArn);
+      }
       funcDef.layers = layers;
     }