In this two-part series, we'll look at building and deploying microservices to Amazon's AWS using Docker.

In this first part, we'll focus on building a simple microservice and packaging it in a docker container, we'll also step through hosting the container on AWS. In part two, we'll assemble a cluster of machines on AWS using Docker Swarm mode.

Make no mistake, this is fairly involved stuff, but I'm going to soften the blow in order to make this topic approachable to a wider audience.

If you're a pro at docker and AWS then you can skim through this article and look forward to part two.

Getting Started with AWS & Docker

Deploying microservices to the cloud is plagued with lots of complexity. To simplify the microservice portion we're going to use an NPM library called Hydra - which will greatly simply the effort while offering considerable scalability benefits. Even if you choose not to use Hydra, the information in this post should help you get started with AWS and Docker.

A quick recap if you're wondering what this Hydra thing is. Hydra is a NodeJS package which facilitates building distributed applications such as Microservices. Hydra offers features such as service discovery, distributed messaging, message load balancing, logging, presence, and health monitoring. As you can imagine, those features would benefit any service living on cloud infrastructure.

If you'd like to learn more, see two of my earlier posts here on RisingStack. The first is Building ExpressJS-based microservices using Hydra, and the second is Building a Microservices Example Game with Distributed Messaging. A microservice game? Seriously? For the record, I do reject claims that I have too much time on my hands. :)

We'll begin by reviewing docker containerization - just in case you're new to this. Feel free to skim or skip over the next section, if you're already familiar with Docker.

Containerization?

Virtual Machine software has ushered in the age of software containerization where applications can be packaged as containers making them easier to manage. Docker is a significant evolution of that trend.

Running microservices inside of containers makes them portable across environments. This greatly helps to reduce bugs which can be found during development as the environment your software runs in locally can match what you run in production.

Packaging a NodeJS microservice inside of a Docker container is straightforward. To begin with, you should download and install the Docker community edition from docker.com - if you haven't already done so.

Here is an overview of the containerization steps:

Build a simple service

Create a Dockerfile

Build a container

Run a container

Let's take a look at each of these steps.

Building a simple microservice

To build our simple microservice we'll use a package called Hydra-express, which creates a microservice using Hydra and ExpressJS. Why not just ExpressJS? By itself, an ExpressJS app only allows you to build a Node server and add API routes. However, that basic server isn't really a complete microservice. Granted that point is somewhat debatable - shades of gray if you will. In comparison, a Hydra-express app includes functionality to discover other Hydra apps and load balance requests between them using presence and health information. Those capabilities will become important when we consider multiple services running and communicating with each other on AWS and in a Docker Swarm cluster. Building Hydra and Hydra-Express apps are covered in more detail in my earlier RisingStack articles.

This approach does however, require that you're running a local instance of Redis or have access to a remote one. In the extremely unlikely event that you're unfamiliar with Redis - checkout this quick start page.

In the interests of time, and to avoid manually typing the code for a basic hydra-express app - we'll install Yeoman and Eric Adum's excellent hydra app generator. A Yeoman generator asks a series of questions and then generates an app for you. You can then customize it to suit your needs. This is similar to running the ExpressJS Generator.

$ sudo npm install -g yo generator-fwsp-hydra

Next, we'll invoke Yeoman and the hydra generator. Name your microservice hello and make sure to specify a port address of 8080 - you can then choose defaults for the remaining options.

$ yo fwsp-hydra fwsp-hydra generator v0.3.1 yeoman-generator v1.1.1 yo v1.8.5 ? Name of the service (`-service` will be appended automatically) hello ? Your full name? Carlos Justiniano ? Your email address? [email protected] ? Your organization or username? (used to tag docker images) cjus ? Host the service runs on? ? Port the service runs on? 8080 ? What does this service do? Says hello ? Does this service need auth? No ? Is this a hydra-express service? Yes ? Set up a view engine? No ? Set up logging? No ? Enable CORS on serverResponses? No ? Run npm install? No create hello-service/specs/test.js create hello-service/specs/helpers/chai.js create hello-service/.editorconfig create hello-service/.eslintrc create hello-service/.gitattributes create hello-service/.nvmrc create hello-service/.gitignore create hello-service/package.json create hello-service/README.md create hello-service/hello-service.js create hello-service/config/sample-config.json create hello-service/config/config.json create hello-service/scripts/docker.js create hello-service/routes/hello-v1-routes.js Done! 'cd hello-service' then 'npm install' and 'npm start'

You'll end up with a folder called hello-service.

$ tree hello-service/ hello-service/ ├── README.md ├── config │ ├── config.json │ └── sample-config.json ├── hello-service.js ├── package.json ├── routes │ └── hello-v1-routes.js ├── scripts │ └── docker.js └── specs ├── helpers │ └── chai.js └── test.js 5 directories, 9 files

In the folder structure above the config directory contains a config.json file. That file is used by Hydra-express to specify information about our microservice.

The config file will look something like this:

{ "environment": "development", "hydra": { "serviceName": "hello-service", "serviceIP": "", "servicePort": 8080, "serviceType": "", "serviceDescription": "Says hello", "plugins": { "logger": { "logRequests": true, "elasticsearch": { "host": "localhost", "port": 9200, "index": "hydra" } } }, "redis": { "url": "127.0.0.1", "port": 6379, "db": 15 } } }

If you're using an instance of Redis which isn't running locally you can specify its location under the hydra.redis config branch. You can also optionally specify a Redis url such as redis://:[email protected]:6379/15 and you can remove the port and db key values from the config.

After cd-ing into the folder you can build using npm install , and after running npm start you should see:

$ npm start > [email protected] start /Users/cjus/dev/hello-service > node hello-service.js INFO { event: 'start', message: 'hello-service (v.0.0.1) server listening on port 8080' } INFO { event: 'info', message: 'Using environment: development' } serviceInfo { serviceName: 'hello-service', serviceIP: '192.168.1.151', servicePort: 8080 }

Take note of the serviceIP address 192.168.1.151 - yours will be different.

Using the IP address and Port above we can access our v1/hello route from a web browser:

Note, I'm using the excellent JSON Formatter chrome extension to view JSON output in all of its glory. Without a similar browser extension you'll just see this:

{"statusCode":200,"statusMessage":"OK","statusDescription":"Request succeeded without error","result":{"greeting":"Welcome to Hydra Express!"}}

OK, let's dockerize this thing!

Creating the Dockerfile

In order to containerize our microservice, we need to provide instructions to Docker. This is done using a text file called a Dockerfile . If you're following along and used the hydra generator, you already have a way to easily create a Dockerfile. You simply type $ npm run docker build and the docker.js file we saw earlier will be invoked to create your Dockerfile and build your container. That's a quick way to get the job done - but if you've never created a Dockerfile following in this section will be educational.

Here is a sample Dockerfile:

FROM node:6.9.4-alpine MAINTAINER Carlos Justiniano [email protected] EXPOSE 8080 RUN mkdir -p /usr/src/app WORKDIR /usr/src/app ADD . /usr/src/app RUN npm install --production CMD ["npm", "start"]

The first line specifies the base image that will be used for your container. We specify the light-weight (Alpine) image containing a minimal Linux and NodeJS version 6.9.4 - however, you can specify the larger standard Linux image using: FROM: node:6.9.4

The EXPOSE entry identifies the port that our microservice listens on. The remaining lines specify that the contents of the current directory should be copied to /usr/src/app inside of the container. We then instruct Docker to run the npm install command to pull package dependencies. The final line specifies that npm start will be invoked when the container is executed. You can learn more on the Dockerfiles documentation page.

Build the container

There is one thing we need to do before we build our container. We need to update our microservice's config.json file. You may be pointing to a local instance of Redis like this:

"redis": { "url": "127.0.0.1", "port": 6379, "db": 15 }

You'll need to change the IP address pointing to localhost at 127.0.0.1 - because when our service is running in a container its network is different! Yes friends, welcome to the world of docker networking. So in the container's network - Redis isn't located at 127.0.0.1 - in fact, Redis is running outside of our container.

There are lots of ways of dealing with this, but one way is simply to change the URL reference to a named DNS entry - like this:

"redis": { "url": "redis", "port": 6379, "db": 15 }

That basically says "when looking for the location of Redis, resolve the DNS entry named redis to an IP address". We'll see how this works shortly.

With the config change and a Dockerfile on hand we're now ready to package our microservice inside of a container.

$ docker build -t cjus/hello-service:0.0.1 .

Note: Don't forget the trailing period which specifies the working directory.

The -t tag for the command above specifies your service name and version. It's a good practice to prefix that entry with your username or company name. For example: cjus/hello-service:0.0.1 If you're using Docker hub to store your containers then you'll definitely need to prefix your container name. We'll touch on Docker hub a bit later.

You should see a long stream of output as your project is being loaded into the container and npm install is being run to create a complete environment for your microservice.

Running our container

We can run our container using one command:

$ docker run -d -p 8080:8080 \ --add-host redis:192.168.1.151 \ --name hello-service \ cjus/hello-service:0.0.1

We use the docker run command to invoke our container and service. The -d flag specifies that we want to run in daemon (background mode) and the -p flag publishes our services ports. The port syntax says: "on this machine use port 8080 (first portion) and map that to the containers internal port (second portion)" which is also 8080. The --add-host allows us to specify a DNS entry called redis to pass to our container - how cool is that? We also name the service using the --name flag - that's useful otherwise docker will provide a random name for our running container. The last portion shown is the service name and version. Ideally, that should match the version in your package.json file.

Communicating with our container

At this point you should be able to open your web browser and point it to http://localhost:8080/v1/hello to access your service - the same way we did earlier when our service was running outside of the container. Using docker commands you can start, stop, remove containers and a whole lot more. Checkout this handy command cheat sheet.

Sharing your containers

Now that you've created a container you can share it with others by publishing it to a container registry such as Docker Hub. You can setup a free account which will allow you to publish unlimited public containers, but you'll only be able to publish one private container. As they say in the drug business: "The first one is free". To maintain multiple private containers you'll need a paid subscription. However, the plans start at a reasonably low price of $7 per month. You can forgo this expense by creating your own local container repository. However, this isn't a useful option when we need to work in the cloud.

I have an account on docker hub under the username cjus . So to push the hello-service container to my docker account I simply use:

$ docker push cjus/hello-service:0.0.1

To pull (download) a container image from my docker hub repo I use this command:

$ docker pull cjus/hello-service:0.0.1

A look at configuration management

If you refer back to our sample microservice's config.json file you'll realize that it got packaged in our docker container. That happened because of this line in our Dockerfile which instructs docker to copy all the files in the current directory into the /usr/src/app folder inside of the docker container.

ADD . /usr/src/app

So that included our ./config folder. Packaging a config file inside of the container isn't the most flexible thing to do - after all, we might need a different config file for each environment our service runs in.

Fortunately, there is an easy way to specify an external config file.

$ docker run -d -p 8080:8080 \ --add-host redis:192.168.1.151 \ -v ~/configs/hello-service:/usr/src/app/config \ --name hello-service \ cjus/hello-service:0.0.1

The example above has a -v flag which specifies a data "volume". The mapping consists of two directories separated by a colon character.

So: source-path : container-path

The volume points to a folder called configs in my home directory. Inside that folder I have a config.json file. That folder is then mapped to the /usr/src/app/config folder inside of the docker container.

When the command above is issued the result will be that the container's /usr/src/app/config will effectively be mapped to my ~/configs folder. Our microservice still thinks it's loading the config from its local directory and doesn't know that we've mapped that folder to our host machine.

We'll look at a much cleaner way of managing config files when we deploy our containers to a docker swarm in part two of this series. For now, we'll just roll with this.

Moving to Amazon Web Services

I have to assume here that you're familiar with using AWS and in particular creating EC2 instances and later ssh-ing into them. And that you're comfortable creating security groups and opening ports. If not, you can still follow along to get a sense of what's involved.

We'll begin by signing into AWS and navigating to the EC2 Dashboard . Once there click on the "Launch Instance" button. On the page that loads select the AWS Marketplace tab. You should see a screen like this:

Search for ECS Optimized to locate the Amazon ECS-Optimized AMI. Amazon created this image for use with its EC2 Container Service. We won't be using ECS and will opt instead to use Docker and later, Docker Swarm. This choice will allow you to use the skills you acquire here on other cloud providers such as Google Cloud and Microsoft's Azure. The reason we're using an ECS Optimized AMI is because it has Docker pre-installed! In part two of this series, we'll use Docker tools to launch AWS EC2 instances and install the docker engine onto them. However, let's not get ahead of ourselves.

For now, select Amazon ECS-Optimized AMI and create an EC2 t2.micro instance. Go ahead and configure it using defaults and a security group which opens port 8080.

Once the EC2 instance is ready you can SSH into it to install our docker container.

$ ssh 54.186.15.17 Warning: Permanently added 'ec2-54-186-15-17.us-west-2.compute.amazonaws.com,54.186.15.17' (ECDSA) to the list of known hosts. Last login: Sat Mar 25 21:47:19 2017 from pool-xx-xxx-xxx-xxx.nwrknj.fios.verizon.net __| __| __| _| ( \__ \ Amazon ECS-Optimized Amazon Linux AMI 2016.09.g ____|\___|____/ For documentation visit, http://aws.amazon.com/documentation/ecs 2 package(s) needed for security, out of 9 available Run "sudo yum update" to apply all updates.

You should run the security updates while you're there.

You can check the version of docker that's running using:

[[email protected] ~]$ docker --version Docker version 1.12.6, build 7392c3b/1.12.6

To ensure that you can pull (download) your private docker containers, you'll need to sign into docker hub using:

$ docker login

To install our microservice we just need to pull it from docker hub.

$ docker pull cjus/hello-service:0.0.1

Note: replace cjus above with your docker user name.

Now we're ready to run it. But we don't just want to execute it on the command line as we did earlier because we need to make sure that our container runs should our EC2 instance reboot. To do that we'll add an two entries to the machine's /etc/rc.local file.

$ sudo vi /etc/rc.local

And add the following entries:

docker rm -f hello-service docker run -d -p 8080:8080 \ --restart always \ --add-host redis:54.202.205.22 \ -v /usr/local/etc/configs/hello-service:/usr/src/app/config \ --name hello-service \ cjus/hello-service:0.0.1

Note: make sure to use your own docker hub user name in the last line above.

Our -v volume flag above specifies the location of the hello-service config file. You'll need to create that folder and copy a config file into it. That will give you the ability to later tweak or extend the settings.

$ sudo mkdir -p /usr/local/etc/configs/hello-service $ cd /usr/local/etc/configs/hello-service

Referring back to our docker run command above, you'll also notice that I specified a Redis location as 54.202.205.22. That's a separate instance from our new EC2 instance. In my example, I've created another EC2 instance to host a Redis docker container. You also have the option of running a docker container on the current machine or on another in the same Amazon VPC. While that works, the recommended solution for production use is to point to an Amazon ElasticCache running a Redis cluster or a service such as RedisLabs.

For our basic tests here, you can add Redis as a docker container using:

$ docker pull redis:3.0.7

Then add this onto the /etc/rc.local file:

docker rm -f redis docker run -d -p 6379:6379 --restart always -v /data:/data --name redis redis:3.0.7

Notice that we're using -v /data:/data above. That will allow Redis to persist its data. You'll need to actually create the /data folder using: sudo mkdir /data .

After making the changes above you can restart your EC2 instance(s) with sudo reboot .

Once the machine restarts you should be able to access our sample microservice through the hosted container.

Recap

In this article, we saw how to build a simple microservice, containerize it, and use the same container on an AWS EC2 instance. Granted, there are lots of different ways of doing this. The example here is intended to be just one simple approach to get you started. With small modifications, you would be able to create lots of different services running across many machines.

The examples in this article and the online docker documentation should give you the tools you need to get started with microservices in the cloud.

In the second part of this series, we'll look at a more advanced approach using a cluster of machines and Docker Swarm mode. Stay tuned!