fix: Fix lambda layers support (#267)

Author: mmeyers-xomly

Diff for: src/Serverless.d.ts

@@ -15,8 +15,10 @@ declare namespace Serverless {
       functions: {
         [key: string]: Serverless.Function
       }
+      layers: { [key: string]: Serverless.Layer }
       package: Serverless.Package
       getAllFunctions(): string[]
+      getAllLayers(): string[]
       custom?: {
         serverlessPluginTypescript?: {
           tsConfigFileLocation: string
@@ -38,6 +40,11 @@ declare namespace Serverless {
     package: Serverless.Package
   }
 
+  interface Layer {
+    handler: string
+    package: Serverless.Package
+  }
+
   interface Package {
     include: string[]
     exclude: string[]

Diff for: src/index.ts

@@ -250,6 +250,15 @@ export class TypeScriptPlugin {
       path.join(this.originalServicePath, SERVERLESS_FOLDER)
     )
 
+    const layerNames = service.getAllLayers()
+    layerNames.forEach(name => {
+      service.layers[name].package.artifact = path.join(
+        this.originalServicePath,
+        SERVERLESS_FOLDER,
+        path.basename(service.layers[name].package.artifact)
+      )
+    })
+
     if (this.options.function) {
       const fn = service.functions[this.options.function]
       fn.package.artifact = path.join(