always use "python" as the path in the layer. this works for python2.7, python3.6 and python3.7

Author: david-mkl

lib/layer.js

@@ -6,46 +6,17 @@ const { writeZip, addTree } = require('./zipTree');
 
 BbPromise.promisifyAll(fse);
 
-/**
- * Get the paths for the compatible runtimes of the layer
- * @param {string[]} list of runtime paths
- */
-function getRunTimeBuildPaths() {
-  const runtimepaths = {
-    'python2.7': 'python',
-    'python3.6': path.join('python', 'lib', 'python3.6', 'site-packages'),
-    'python3.7': path.join('python', 'lib', 'python3.7', 'site-packages')
-  };
-
-  let runtimes = [];
-
-  // Defer to Layer config first
-  if (this.options.layer.compatibleRuntimes) {
-    runtimes = this.options.layer.compatibleRuntimes;
-    // If none provided, assume the provider runtime
-  } else if (this.serverless.service.provider.runtime) {
-    runtimes = [this.serverless.service.provider.runtime];
-    // If still no runtime found, just assume latest python
-  } else {
-    runtimes = ['python3.7'];
-  }
-
-  return BbPromise.resolve(runtimes.map(runtime => runtimepaths[runtime]));
-}
-
 /**
  * Zip up requirements to be used as layer package.
- * @param {string[]} list of paths where the requirements should be put in the layer
  * @return {Promise} the JSZip object constructed.
  */
-function zipRequirements(runtimepaths) {
+function zipRequirements() {
   const rootZip = new JSZip();
   const src = path.join('.serverless', 'requirements');
+  const runtimepath = 'python';
 
-  return BbPromise.each(runtimepaths, runtimepath =>
-    addTree(rootZip.folder(runtimepath), src)
-  ).then(() =>
-    writeZip(rootZip, path.join('.serverless', 'pythonRequirementsLayer.zip'))
+  return addTree(rootZip.folder(runtimepath), src).then(() =>
+    writeZip(rootZip, path.join('.serverless', 'pythonRequirements.zip'))
   );
 }
 
@@ -80,7 +51,6 @@ function layerRequirements() {
   this.serverless.cli.log('Packaging Python Requirements Lambda Layer...');
 
   return BbPromise.bind(this)
-    .then(getRunTimeBuildPaths)
     .then(zipRequirements)
     .then(createLayers);
 }