mean.md

#Get MEAN with Amazon OpsWorks

##Introduction The MEAN stack is a JavaScript based application stack that has recently become more and more popular. MEAN is an acronym for MongoDB, Express, Angular.js and Node.js.

MongoDB is a document-oriented NoSQL database system. MongoDB saves data in JSON-like documents with dynamic schema (BSON, binary JSON) which makes it easier to pass data between client and server.

Express is lightweight framework used to build web applications in Node.js inspired by the Ruby framework, Sinatra. It provides a number of robust features for building single and multi page web application.

AngularJS is an open-source web application framework to create web applications that only require HTML, CSS, and JavaScript on the client side. AngularJS' goal is to enhance web applications with model–view–controller (MVC) capability, to make both development and testing easier.

Node.js is a server side JavaScript execution environment. Internally it uses the Google V8 JavaScript engine to execute code, and a large part of the basic modules are written in JavaScript. Node.js applications are designed to maximize throughput and efficiency, using non-blocking I/O and asynchronous events.

In this article we are going to show how to create a MEAN stack using OpsWorks: we'll deploy a MongoDB Replica Set using a custom layer and the community cookbooks, we'll extend the built-in Node.js layer with some custom recipes and we'll add a Elastic Load Balancer (ELB) to the Node.js layer.

##Create a Stack First, let's create a new stack, give it a name - e.g., MEAN - and select your region of choice.

In the Advanced settings, change the Chef version to 11.04 and set Use custom Chef Cookbooks to Yes. Set Repository type to S3 and enter the URL to your custom cookbooks.

We'll use the Custom JSON setting to override some MongoDB default attributes and to pass some data to our custom recipes.

{
	"mongodb" : {
		"install_method": "mongodb-org",
		"replicaset_name": "mean-rs",
		"cluster_name": "mean-cluster",
		"auto_configure": {
			"replicaset": true
		},
		"config": {
			"replSet": "mean-rs",
			"dbpath" : "/data",
			"logpath" : "/log/mongodb.log"
		}
	},
	"deploy": {
		"mean_app": {
			"db_user" : "meanuser",
			"db_password" : "mean"	
		}
	}
}

Click the Add Stack button at the bottom of the page to create the stack.

##Add the MongoDB Replica Set Custom Layer Now, let's create a custom layer for the MongoDB Replica Set, enter MongoDB as a name and mongodb as a short name and click Add Layer (Note: the custom recipes refer to the MongoDB layer using this shortname). Click the layer's Recipes action, click on Edit at the top of the page and scroll to the Custom Chef Recipes section.

Enter mean::create-journal-link, mongodb::10gen_repo, mongodb::default and mean::setup-mongo-shell next to Setup and add it to the list. These recipes install MongoDB Server and the shell tool from the MongDB Inc. repository and create a symlink for the journal in the data directory; they will be executed after an instance is booted up. Add mongodb::replicaset and mean::configure-mean-user to the Configure recipes list; these recipes configure the instances to be part od a Replica Set and create a user for the app that we'll deploy later on. Click the Save button at the bottom to save the updated configuration.

Click the layer's EBS Volumes action and set the EBS optimized instances to Yes. Add the EBS Volumes to be attached to each instance in this layer: one RAID1 volume for the data, one volume for the journal and one volume for the logs. Adjust the size and PIOPS of each volume according to your specific needs. Also, if you changed the data or log path in the Custom JSON passed to each instance, make sure to reflect those changes in the volume mount points. This setup was done following some recommandations from MongoDB Inc. for deployment on Amazon EC2.

Finally, add your instances. For a MongoDB Replica Set you'll need an odd number of instances, at least three. Also, make sure your instances are in different Availability Zones (AZs) to increase the availability and fault-tolerance of your database.

##Add a Node.js Layer For the Application layer we'll use a built-in Node.js Layer. Create a new Layer in your stack, select Node.js App Server as Layer Type and click Add Layer at the bottom left of your screen.

Click the layer's Recipes action, click on Edit at the top of the page and scroll to the Custom Chef Recipes section. Enter mean::deploy-mean-app next to Deploy and add it to the list. This recipe will create a configuration file for the MEAN application that contains the MongoDB Replica Set connection string. Click the Save button at the bottom to save the updated configuration.

Add instances to the Node.js Layer. Again, make sure your instances are in different Availability Zones (AZs) to increase the availability and fault-tolerance of your application.

##Add an Elastic Load Balancer to the Node.js Layer To spread the requests across the instances in the Node.js Layer we'll attach an Elastic Load Balancer (ELB) to the Layer. You can use an existing ELB or create a new one from the EC2 Management Console. Make sure that there are no instances registered to the ELB.

Click the layer's Network action, click on Edit at the top of the page and select your ELB from the drop-down next to Elastic Load Balancer. Click the Save button at the bottom to save the updated configuration.

##Add the MEAN ToDo Sample app Lastly, we'll add a ToDo sample Node.js app. Add a new App, enter Mean App as name an select Node.js from the Type drop-down menu (Note: if you change the app name, remember to change the respctive section under deploy in the Custom JSON stack setting). Leave the Data source type set to None as we'll use our custom MongoDB Layer as data source for our app. Select the repository type and URL for the app and click on Save at the bottom of the page.

Now we can start our instances and we'll be able to access our MEAN ToDo sample app using the ELB DNS name.

##Final words In this article we showed how to deploy a MongoDB Replica Set using a custom layer and the community cookbooks and how to deploy a Node.js application that uses MongoDB as data source. Thanks to Reza Spagnolo for the hints on the MongoDB Replica Set recipes.