Added feature to use the default noDeploy list with custom list

README.md

@@ -228,6 +228,8 @@ custom:
       - pytest
 ```
 
+N.B. When using a `Pipfile`, instead of `requirements.txt`, there is no need to specify `pytest` in the `noDeploy` list if you have specified it as a dev dependency.
+
 To include the default omitted packages, set the `noDeploy` option to an empty
 list:
 ```yaml
@@ -236,6 +238,15 @@ custom:
     noDeploy: []
 ```
 
+Or to use both a custom list of ommitted packages, and the defaults listed above use the `addDefaultNoDeploys` option e.g.:
+```yaml
+custom:
+  pythonRequirements:
+    addDefaultNoDeploys: true
+    noDeploy:
+      - external_layer_provided_package
+```
+
 ## Extra Config Options
 ### Caching
 You can enable two kinds of caching with this plugin which are currently both DISABLED by default.  First, a download cache that will cache downloads that pip needs to compile the packages.  And second, a what we call "static caching" which caches output of pip after compiling everything for your requirements file.  Since generally requirements.txt files rarely change, you will often see large amounts of speed improvements when enabling the static cache feature.  These caches will be shared between all your projects if no custom cacheLocation is specified (see below).

index.js

@@ -22,6 +22,20 @@ BbPromise.promisifyAll(fse);
  * Plugin for Serverless 1.x that bundles python requirements!
  */
 class ServerlessPythonRequirements {
+  get default_no_deploys() {
+    return [
+      'boto3',
+      'botocore',
+      'docutils',
+      'jmespath',
+      'python-dateutil',
+      's3transfer',
+      'six',
+      'pip',
+      'setuptools'
+    ];
+  }
+
   /**
    * get the custom.pythonRequirements contents, with defaults set
    * @return {Object}
@@ -53,23 +67,17 @@ class ServerlessPythonRequirements {
         cacheLocation: false,
         staticCacheMaxVersions: 0,
         pipCmdExtraArgs: [],
-        noDeploy: [
-          'boto3',
-          'botocore',
-          'docutils',
-          'jmespath',
-          'python-dateutil',
-          's3transfer',
-          'six',
-          'pip',
-          'setuptools'
-        ],
+        noDeploy: this.default_no_deploys,
+        addDefaultNoDeploys: false,
         vendor: ''
       },
       (this.serverless.service.custom &&
         this.serverless.service.custom.pythonRequirements) ||
         {}
     );
+    if (options.addDefaultNoDeploys) {
+      options.noDeploy = options.noDeploy.concat(this.default_no_deploys);
+    }
     if (options.dockerizePip === 'non-linux') {
       options.dockerizePip = process.platform !== 'linux';
     }