feat(serverless-example): add basic serverless SNS example

Author: mefellows

examples/serverless/.gitignore

@@ -0,0 +1 @@
+.serverless

examples/serverless/README.md

@@ -0,0 +1,28 @@
+# Serverless example
+
+Fictional application running using the [Serverless](https://github.com/serverless/serverless) framework.
+
+**Message Producer**
+
+Small utility that takes a request and publishes a message to an SQS queue.
+
+**Message Consumer**
+
+Lambda function that reads from SQS and processes the data.
+
+
+## Deploy service
+
+Ensure you have valid AWS credentials in your environment, and then run;
+
+```sh
+export AWS_ACCOUNT_ID=1234xxxx5678 # Required by function at runtime
+serverless deploy -v
+```
+
+## How we set this up
+
+```sh
+npm install -g serverless
+serverless create --template aws-nodejs --path sqs-publisher
+```

examples/serverless/consumer/index.js

@@ -0,0 +1,27 @@
+'use strict';
+
+const AWS = require('aws-sdk');
+
+// Consumer handler, responsible for extracting message from SNS
+// and dealing with lambda-related things.
+module.exports.handler = (event, context, callback) => {
+  console.log("Received event from SNS");
+
+  event.Records.forEach(e => {
+    console.log("Event:", JSON.parse(e.Sns.Message));
+    consumeEvent(e)
+  });
+
+  callback(null, {
+    event
+  });
+};
+
+// Actual consumer code, has no Lambda/AWS/Protocol specific stuff
+// This is the thing we test in the Consumer Pact tests
+const consumeEvent = (event) => {
+
+  // save in dynamo or something...
+  console.log('consuming event', event)
+
+}

examples/serverless/publisher/.gitignore

@@ -0,0 +1,6 @@
+# package directories
+node_modules
+jspm_packages
+
+# Serverless directories
+.serverless

examples/serverless/publisher/index.js

@@ -0,0 +1,45 @@
+'use strict';
+
+const AWS = require('aws-sdk');
+
+const TOPIC_ARN = process.env.TOPIC_ARN;
+
+// Handler is the Lambda and SNS specific code
+// The message generation logic is separated from the handler itself
+// in the
+module.exports.handler = (event, context, callback) => {
+  const message = createEvent(event);
+
+  const sns = new AWS.SNS();
+
+  const params = {
+    Message: message.body,
+    TopicArn: TOPIC_ARN
+  };
+
+  sns.publish(params, (error, data) => {
+    if (error) {
+      callback(error);
+    }
+
+    console.log("Message successfully published to queue")
+    callback(null, {
+      message: 'Message successfully published to SNS topic "pact-events"',
+      event
+    });
+  });
+
+  callback(null, message);
+};
+
+// Separate your producer code, from the lambda handler.
+// No Lambda/AWS/Protocol specific stuff in here..
+const createEvent = (event) => {
+  return {
+    statusCode: 200,
+    body: JSON.stringify({
+      message: 'Go Serverless v1.0! Your function executed successfully!',
+      input: event,
+    }),
+  };
+};

examples/serverless/serverless.yml

@@ -0,0 +1,26 @@
+# Serverless SNS
+service: pact-events
+
+provider:
+  name: aws
+  runtime: nodejs6.10
+  iamRoleStatements:
+    - Effect: "Allow"
+      Resource: "*"
+      Action:
+        - "sns:*"
+  environment:
+        ACCOUNT_ID: { "Ref": "AWS::AccountId" }
+        # TOPIC_ARN: { "Ref": "SNSTopicPactevents" }
+        TOPIC_ARN: { "Fn::Join":  ["", ["arn:aws:sns:us-east-1:", { "Ref": "AWS::AccountId" }, ":pact-events"] ] }
+
+package:
+   individually: true
+
+functions:
+  publisher:
+    handler: publisher/index.handler
+  consumer:
+    handler: consumer/index.handler
+    events:
+      - sns: pact-events