Introduction

Yesterday (!) I asked in the Gophers slack for recommendations for deployment of static Go binaries, as I was in the process of deploying a demo for another blog post I’m working on. I was told to check out Scaleway among other things, and found it to be an excellent option for simple and cheap hosting. It currently provides data centres in Paris and Amsterdam, which is perfect for me. I then found I could automatically build and deploy docker images via Docker Cloud, directly from GitHub. It was all so easy that I thought I’d put together a quick walkthrough of the steps I followed to get everything up and running.

Spin up the server

Register with Scaleway, add your SSH public key and start a VC1S server. We could get fancy here and use an ARM backed server, but I don’t see the need so I opted for the x86 machine. 2 threads, 2GB memory, 50GB SSD and it costs us €2.99 per month at most, or as little as €0.006 per hour. The fee also includes a public IPv4 address. What a bargain!

Go for the Docker image listed under the ImageHub section, as we’ll need docker installed on the machine for later.

While the machine is spinning up it’s time to set up our Docker Cloud account.

Docker Cloud

Register or login if you already have a Docker hub account, and navigate to Cloud Settings. You’ll need to link your GitHub (or Bitbucket) account here to enable auto-build and auto-redeployment of images. The Docker side of this is entirely free of charge, you don’t even have to enter a credit card into your account, for that ultimate peace of mind that there won’t be any nasty surprises down the line.

Register the Scaleway node to Docker Cloud

Once registered, we need to add our Scaleway node as a Docker node. First things first, Docker Cloud requires us to open a couple of inbound ports, namely 2375/tcp, 6783/tcp and 6783/udp. While we’re here, you probably want to add an inbound rule for 443/tcp (you do plan to serve your app over HTTPS, right?).

Once the security group has been configured, go back to Docker Cloud and lick the + button in the top right and select Bring Your Own Node. It’ll give you a command that we need to run on our Scaleway node, so now it’s time to ssh onto the Scaleway node.

ssh root@your-scaleway-node-ip

Once you’ve accepted the host key, proceed to run the snippet from the Docker Cloud page. If everything works, your Docker Cloud page should tell you that the node was successfully registered!

Sidenote: Multi-stage Docker Builds

At this point I want to mention that this works particularly well if you utilize multi-stage docker builds. They’re a new feature in Docker 17.05, so ensure you’ve selected 17.05 as the docker version in your Docker Cloud settings. See this Dockerfile for an example:

# Build
FROM golang AS build
ADD . /go/src/github.com/myrepo/myapp
ENV CGO_ENABLED=0
RUN cd /go/src/github.com/myrepo/myapp && go build -o /app

# Production
FROM scratch
COPY --from=build /app /app
EXPOSE 443
ENTRYPOINT ["/app"]

We use the official golang image to build the application, then we just take the static binary and stuff it into a minimal container environment. Amazingly simple and you end up with a container not much larger than the size of the binary itself. Truly we are living in the future.

Setting up the Docker Cloud repository

We’ve added Docker Cloud to our GitHub already, so now we can go ahead and create a repository from GitHub. I’m assuming you’ve already got your source repo on github so it should just be a matter of clicking Create and selecting the repository to link it to in the settings. It’ll automatically detect if there is a Dockerfile in the root of your repository. Otherwise, just select the path to the Dockerfile. Your new Docker Cloud repository will automatically be configured to build on new merges to master.

Deploying the app

Go to the repository page we just created. See that alluring Launch Service button in the top right? It’s time to launch our service! Click it and on the next page you’ll get a new interface allowing you to customize the forwarded ports, volumes, commands and many other things. Most significantly, make sure to turn on AUTOREDEPLOY. This will automatically redeploy your service when a new one has been successfully built from your source.

Once you’ve tweaked the dials and dotted the i’s, go ahead and click Create & Deploy. It’ll spin up your new container on the Scaleway node we registered earlier. Magic!

🍾

Congratulations! You’ve now got your demo app running in a Docker container on your Scaleway node, with automatic redeployment triggered straight from your GitHub pushes. Lean back in your chair and crack open a cold one, you deserve it!

If you liked this article, or you have anything you’d like to add or correct, don’t hesitate to reach out to me on twitter @johanbrandhorst or on Gophers Slack under jbrandhorst. Thanks for reading!