Add AWS Lambda Layer Support

README.md

@@ -163,6 +163,38 @@ custom:
 ```
 This will remove all folders within the installed requirements that match
 the names in `slimPatterns`
+
+### Lamba Layer
+Another method for dealing with large dependencies is to put them into a
+[Lambda Layer](https://docs.aws.amazon.com/lambda/latest/dg/configuration-layers.html).
+Simply add the `layer` option to the configuration.
+```yaml
+custom:
+  pythonRequirements:
+    layer: true
+```
+The requirements will be zipped up and a layer will be created automatically.
+Now just add the reference to the functions that will use the layer.
+```yaml
+functions:
+  hello:
+    handler: handler.hello
+    layers:
+      - {Ref: PythonRequirementsLambdaLayer}
+```
+If the layer requires additional or custom configuration, add them onto the `layer` option.
+```yaml
+custom:
+  pythonRequirements:
+    layer:
+      name: ${self:provider.stage}-layerName
+      description: Python requirements lamba layer
+      compatibleRuntimes:
+        - python3.7
+      licenseInfo: GPLv3
+      allowedAccounts:
+        - '*'
+```
 ## Omitting Packages
 You can omit a package from deployment with the `noDeploy` option. Note that
 dependencies of omitted packages must explicitly be omitted too. By default,
@@ -423,3 +455,4 @@ zipinfo .serverless/xxx.zip
  * [@andrewfarley](https://github.com/andrewfarley) - Implemented download caching and static caching
  * [@bweigel](https://github.com/bweigel) - adding the `slimPatternsAppendDefaults` option & fixing per-function packaging when some functions don't have requirements & Porting tests from bats to js!
  * [@squaresurf](https://github.com/squaresurf) - adding usePoetry option
+ * [@david-mk-lawrence](https://github.com/david-mk-lawrence) - added Lambda Layer support

index.js

@@ -10,6 +10,7 @@ const {
   packRequirements
 } = require('./lib/zip');
 const { injectAllRequirements } = require('./lib/inject');
+const { layerRequirements } = require('./lib/layer');
 const { installAllRequirements } = require('./lib/pip');
 const { pipfileToRequirements } = require('./lib/pipenv');
 const { pyprojectTomlToRequirements } = require('./lib/poetry');
@@ -32,6 +33,7 @@ class ServerlessPythonRequirements {
         slimPatterns: false,
         slimPatternsAppendDefaults: true,
         zip: false,
+        layer: false,
         cleanupZipHelper: true,
         invalidateCaches: false,
         fileName: 'requirements.txt',
@@ -96,6 +98,12 @@ class ServerlessPythonRequirements {
       }`;
       options.dockerImage = options.dockerImage || defaultImage;
     }
+    if (options.layer) {
+      // If layer was set as a boolean, set it to an empty object to use the layer defaults.
+      if (options.layer === true) {
+        options.layer = {};
+      }
+    }
     return options;
   }
 
@@ -170,6 +178,7 @@ class ServerlessPythonRequirements {
       }
       return BbPromise.bind(this)
         .then(removeVendorHelper)
+        .then(layerRequirements)
         .then(() =>
           injectAllRequirements.bind(this)(
             arguments[1].functionObj &&

lib/inject.js

@@ -72,6 +72,11 @@ function moveModuleUp(source, target, module) {
  * @return {Promise} the combined promise for requirements injection.
  */
 function injectAllRequirements(funcArtifact) {
+  if (this.options.layer) {
+    // The requirements will be placed in a Layer, so just resolve
+    return BbPromise.resolve();
+  }
+
   this.serverless.cli.log('Injecting required Python packages to package...');
 
   if (this.serverless.service.package.individually) {

lib/layer.js

@@ -0,0 +1,60 @@
+const BbPromise = require('bluebird');
+const fse = require('fs-extra');
+const path = require('path');
+const JSZip = require('jszip');
+const { writeZip, addTree } = require('./zipTree');
+
+BbPromise.promisifyAll(fse);
+
+/**
+ * Zip up requirements to be used as layer package.
+ * @return {Promise} the JSZip object constructed.
+ */
+function zipRequirements() {
+  const rootZip = new JSZip();
+  const src = path.join('.serverless', 'requirements');
+  const runtimepath = 'python';
+
+  return addTree(rootZip.folder(runtimepath), src).then(() =>
+    writeZip(rootZip, path.join('.serverless', 'pythonRequirements.zip'))
+  );
+}
+
+/**
+ * Creates a layer on the serverless service for the requirements zip.
+ * @return {Promise} empty promise
+ */
+function createLayers() {
+  this.serverless.service.layers['pythonRequirements'] = Object.assign(
+    {
+      artifact: path.join('.serverless', 'pythonRequirements.zip'),
+      name: `${this.serverless.service.stage}-python-requirements`,
+      description:
+        'Python requirements generated by serverless-python-requirements.',
+      compatibleRuntimes: [this.serverless.service.provider.runtime]
+    },
+    this.options.layer
+  );
+
+  return BbPromise.resolve();
+}
+
+/**
+ * Creates a layer from the installed requirements.
+ * @return {Promise} the combined promise for requirements layer.
+ */
+function layerRequirements() {
+  if (!this.options.layer) {
+    return BbPromise.resolve();
+  }
+
+  this.serverless.cli.log('Packaging Python Requirements Lambda Layer...');
+
+  return BbPromise.bind(this)
+    .then(zipRequirements)
+    .then(createLayers);
+}
+
+module.exports = {
+  layerRequirements
+};