Deploying Prototypes using Docker

Table of contents

• Motivation
• Why Docker
• Writing a Dockerfile
• Deploying to AWS
  • Provisioning a machine
  • Deploying the service
• A simple deploy script

Motivation

Why would you want to go through the hassle of deploying your prototypes in the first place? I think there are a couple of things that makes it worth your effort.

First off, I personally get way more motivated when I know that the thing I’m working on is actually live somewhere on the web, even if it’s behind an obscure IP address. It’s much more fun to add a feature or fix a bug when you know you can push it live easily.

Secondly, in the best case scenario your prototype will grow into a proper product at some point and you’ll have to deploy it anyway. By deploying early, even if all it does is print ‘‘Hello World’’, you’ll catch issues along the way which will allow you to incrementally improve your product in a way that’s still deployable in the end.

Finally I hope to show you that if you’re willing to compromise on some of the aspects of deploying your service (such as availability, auto scaling etc.) then it really isn’t a lot of work. In fact I’ll show you a single shell script you can run that gets the job done.

It was a fun experience helping my brother deploy his service as the requirements were so different from what I usually have to deal with when automating our deployments at Famly. I worry about the availability of the service, configuring auto-scaling, ensuring the logs are persisted and queryable, and things like that. However, in this case we didn’t really care about any of these things – Instead our main focus was simplicity and ease of automation.

Simplicity in this case meant having as few moving parts as possible and keeping the number of new concepts my brother had to learn to a minimum, while ensuring that the ones he did have to learn would be useful to him in other contexts as well. I decided that the simplest solution would be to use docker and docker-machine.

Why Docker

From the perspective of using tools that might be useful to know in other contexts I believe that Docker is an obvious choice; if you know how to containerize your application then you’ll be able to run it almost anywhere (contrast that to learning how to set up your application using Elastic Beanstalk for example). Given that you can containerize almost anything this means that if you’re familiar with Docker you’ll be able to run almost anything almost anywhere 😉

The ability to iterate quickly on the Dockerfile and run it locally before trying to deploy it was also a key factor; once it runs locally it you should be able to deploy it easily as well.

Writing a Dockerfile

The first step is to write a Dockerfile for your application. In the case of python you can base it off a Linux distribution you know or simply go for one of the official python images.

I won’t go into the details of writing a Dockerfile in this post – The official documentation and best-practices guide contains all the information you need to get started.

If you don’t want to write a Dockerfile for one of your own projects but still want to try deploying something to AWS then feel free to use the small example I’ve created.

Deploying to AWS

At this point I assume you have a Docker image that you’ve been able to run locally, so now it’s time to deploy it. 🚀

Provisioning a machine

docker-machine is a tool that makes it possible to run docker commands on your machine as you’re used to, but in reality they will be running on a remote machine.

Before you can deploy anything you need to have somewhere to deploy it to; you need to rent a server. Normally with AWS you’d have to launch an EC2 instance, give it the right roles etc. This is where docker-machine comes in handy. The following command will provision a machine and open port 80 so it can accept HTTP traffic.

docker-machine create \
    --amazonec2-open-port 80 \
    --amazonec2-region eu-central-1 \
    --amazonec2-instance-type t2.micro \
    --driver amazonec2 \
    <YOUR_MACHINE_NAME>

The instance type is set to t2.micro which is one of the cheapest server you can buy (See the full list of instance types here for the various regions).

You can read the documentation for each of the command line arguments here.

export PATH="/usr/local/Cellar/docker-machine/0.12.2/bin:$PATH"

Deploying the service

Now that we have a machine we can deploy our service to it. To run your docker commands on the remote Docker machine you first have to tell docker to execute commands in that context. You do that by using the following command.

eval $(docker-machine env <YOUR_MACHINE_NAME>)

Future docker commands in your shell session will be executed on the remote docker machine. If you close your terminal you’ll have to run the command above again in case you want to speak with the remote docker machine.

Before you can run the image on the machine you first have to build the image on it. This will basically transfer all of the files in your current folder unto the machine and then build the image there. If you’re using my small example then you can build the image with the following command

docker build --tag deploying-prototypes:local .

Finally start a Docker container based on the image.

docker run \
    --detach \
    --publish 80:80 \
    deploying-prototypes:local

See that it works 🎉

echo http://$(docker-machine ip <YOUR_MACHINE_NAME>)

Once you’re done experimenting you might want to stop the machine so you won’t be billed if you’re not using it.

docker-machine stop <YOUR_MACHINE_NAME>

A simple deploy script

In the section above you deployed the service manually by writing a set of commands in the shell. Once you’ve done that a couple of times you’ll get tired of it, so here’s a deploy script that I wrote that automates it for you. It assumes that your Docker image listens for HTTP traffic on port 80 and that port 80 is exposed on the machine (which it is if you used the docker-machine command above to create it).

Download the script and make it executable.

curl https://gist.githubusercontent.com/mads-hartmann/415cba506a538f35a992598c9221432d/raw/98260522a6358feb6c4b70ad503c2e6bbe9b5ce8/prototype-deploy.sh > prototype-deploy.sh
chmod +x prototype-deploy.sh

Now you can deploy any Docker service to any Docker machine like this (assuming your current folder contains the script and a Dockerfile)

./prototype-deploy.sh <YOUR_MACHINE_NAME> <IMAGE_NAME> <CONTAINER_NAME>

Where the <IMAGE_NAME> and <CONTAINER_NAME> is completely up to you.

Have fun deploying your next prototype, and let me know in the comments below if you found it useful or have any questions 🙌