Every Continuous Integration process starts with a code that is checked out from a repository. We'll use the GitHub repository vfarcic/go-demo (https://github.com/vfarcic/go-demo) throughout the book. It contains the code of the service we'll use throughout the book. The service is written in Go (https://golang.org/). Fear not! Even though I consider it one of the best currently available languages, you will not be required to learn Go. We'll use the go-demo service only as a demonstration of the processes explained throughout the book. Even though I strongly recommend learning Go, the book does not assume any knowledge of the language. All the examples will be programming language agnostic.

Let's get going and check out the go-demo code:

git clone https://github.com/vfarcic/go-demo.git

cd go-demo

Some of the files will be shared between the host file system and Docker Machines we'll start creating soon. Docker Machine makes the whole directory that belongs to the current user available inside the VM. Therefore, please make sure that the code is checked out inside one of the user's sub-folders.

Now that we have the code checked out from the repository, we need a server that we'll use to build and run tests. For now, we'll use Docker Machine, since it provides an easy way to create a "Docker ready" VMs on our laptops.

The Docker Machine (https://docs.docker.com/machine/overview/) is a tool that lets you install Docker Engine on virtual hosts, and manage the hosts with the docker-machine commands. You can use Machine to create Docker hosts on your local Mac or Windows box, on your company network, in your data center, or on cloud providers like AWS or DigitalOcean.

Using docker-machine commands, you can start, inspect, stop, and restart a managed host, upgrade the Docker client and daemon, and configure a Docker client to talk to your host.

Machine was the only way to run Docker on Mac or Windows previous to Docker v1.12. Starting with the beta program and Docker v1.12, Docker for Mac and Docker for Windows are available as native apps and the better choice for this use case on newer desktops and laptops. I encourage you to try out these new apps. The installers for Docker for Mac and Docker for Windows include Docker Machine, along with Docker Compose.

Let's create our first server called go-demo use the following command:

docker-machine create -d virtualbox go-demo

The command should be self-explanatory. We specified virtualbox as the driver (or Hyper-V if you're running Docker for Windows) and named the machine go-demo:

Now that the machine is running, we should instruct our local Docker Engine to use it, use the following command:

docker-machine env go-demo

The docker-machine env go-demo command outputs environment variables required for the local engine to find the server we'd like to use. In this case, the remote engine is inside the VM we created with the docker-machine create command.

The output is as follows:

export DOCKER_TLS_VERIFY="1"
export DOCKER_HOST="tcp://192.168.99.100:2376"
export DOCKER_CERT_PATH="/Users/vfarcic/.docker/machine/machines/go-demo"
export DOCKER_MACHINE_NAME="go-demo"

We can envelop the env command into an eval that will evaluate the output and, in this case, create the environment variables using the following command:

eval $(docker-machine env go-demo)

From now on, all the Docker commands we execute locally will be channeled to the engine running inside the go-demo machine.

Now we are ready to run the first two steps in the CI flow. We'll execute unit tests and build the service binary.