Initial Environment Variables from AWS Systems Manager Parameter Stor…

…e sample.

rest-environment-ssm/README.md

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+# Sample: Environment Variables from AWS Systems Manager Parameter Store
+
+This sample serverless application illustrates how to implement REST services whose functions are passed [environment variables][sls-envvar] sourced from [AWS Systems Manager Parameter Store][aws-paramstore]. 
+
+Environment variables declared in the `provider` block are passed to all functions. Environment variables declared in a function block are passed only to that function.
+
+## How to Use
+
+### Create Parameters
+
+Before deploying the serverless application you must create the parameters in AWS Systems Manager Parameter Store. Sign into the AWS console and navigate to [AWS Systems Manager](https://console.aws.amazon.com/systems-manager). Select _Parameter Store_ from the left side navigation menu.
+
+In this example, [parameters are organized into a hierarchy][aws-paramhierarchy] with three levels:
+
+/ServiceName/Stage/ParameterName
+
+In the serverless specification, the parameters are retrieved with dynamic references to the service name and stage using the following syntax: `${ssm:/${self:service}/${self:provider.stage}/greeting-audience}`.
+
+Create three SSM parameters to hold values for the `greeting-audience` varible in three stages: dev, qa, and prod. The parameters are:
+
+```
+/samples-environment-ssm/dev/greeting-audience     # Value=Developers
+/samples-environment-ssm/qa/greeting-audience      # Value=Testers
+/samples-environment-ssm/prod/greeting-audience    # Value=World
+```
+
+### Install Dependencies
+
+Install the project dependencies with the Yarn package manager. Navigate to the application base directory and issue the following command:
+
+```
+yarn install
+```
+
+### Run the Application
+
+Run the serverless application in offline mode. Navigate to the application base directory and issue the following command:
+
+```
+# Deploy to 'dev' stage by default
+sls deploy
+
+OR
+
+# Deploy to a specific stage
+sls deploy --stage prod
+```
+
+Test the application by calling the API endpoints:
+- `GET /hello`
+- `GET /goodbye`
+
+Try deploying the application to different stages. Notice that the correct parameter value is used for each environment.
+
+## See Also
+[Serverless Functions - Environment Variables][sls-envvar]  
+[Reference Variables using the SSM Parameter Store][sls-varssm]  
+[AWS Systems Manager Parameter Store][aws-paramstore]  
+[Organizing Parameters into Hierarchies][aws-paramhierarchy]  
+
+[sls-envvar]: https://serverless.com/framework/docs/providers/aws/guide/functions/#environment-variables "Environment Variables | Serverless Docs"
+[sls-varssm]: https://serverless.com/framework/docs/providers/aws/guide/variables#reference-variables-using-the-ssm-parameter-store "Reference Variables using the SSM Parameter Store | Serverless Docs"
+[aws-paramstore]: https://docs.aws.amazon.com/systems-manager/latest/userguide/systems-manager-paramstore.html "AWS Systems Manager Parameter Store | AWS Docs"
+[aws-paramhierarchy]: https://docs.aws.amazon.com/systems-manager/latest/userguide/sysman-paramstore-su-organize.html "Organizing Parameters into Hierarchies | AWS Docs"

rest-environment-ssm/index.js

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+const serverless = require('serverless-http');
+const express = require('express');
+const app = express();
+
+// Environment variables with defaults
+const GREETING_PREFIX = process.env.GREETING_PREFIX || 'Aloha';
+const GREETING_AUDIENCE = process.env.GREETING_AUDIENCE || 'World';
+
+_getMessage = (prefix, audience) => {
+  return `${prefix} ${audience}!`;
+};
+
+app.get('/hello', function(req,res) {
+  res.send(_getMessage(GREETING_PREFIX, GREETING_AUDIENCE));
+});
+
+app.get('/goodbye', function(req,res) {
+  res.send(_getMessage(GREETING_PREFIX, GREETING_AUDIENCE));
+});
+
+module.exports.handler = serverless(app);

rest-environment-ssm/package.json

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+{
+  "name": "serverless-samples-environment-ssm",
+  "version": "1.0.0",
+  "main": "index.js",
+  "repository": "https://github.com/mwarman/serverless-samples",
+  "author": "Matt Warman",
+  "license": "Apache-2.0",
+  "private": false,
+  "dependencies": {
+    "express": "^4.16.4",
+    "serverless-http": "^1.9.1"
+  }
+}

rest-environment-ssm/serverless.yml

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+service: samples-environment-ssm
+
+provider:
+  name: aws
+  runtime: nodejs8.10
+  region: us-east-1
+  stage: ${opt:stage, 'dev'}
+  memorySize: 128
+  environment:
+    GREETING_AUDIENCE: ${ssm:/${self:service}/${self:provider.stage}/greeting-audience}
+
+functions:
+  hello:
+    handler: index.handler
+    environment:
+      GREETING_PREFIX: 'Hello'
+    events:
+      - http: GET /hello
+  goodbye:
+    handler: index.handler
+    environment:
+      GREETING_PREFIX: 'Goodbye'
+    events:
+      - http: GET /goodbye