Using the Dockerfile¶
New in version 0.3.1.
Note
Please review the getting started guide for more detailed information about setting up a cluster.
Setup¶
Before you begin, it is recommended that you run the security-setup script to configure authentication and authorization for the various components.
Next, you will need to setup a Terraform template (*.tf file) in the root directory for the cloud provider of your choices. See the following links for more information:
Finally, you need to create a custom ansible playbook for your cluster. You can copy sample.yml to mantl.yml in your root directory to get started.
Building a Docker Image¶
Now you’ll be able to build a docker image from the Dockerfile:
docker build -t mi .
In this example, we are tagging the image with the name mi which we will be using later in this guide.
Running a Container¶
Now we can run a container from our image to provision a new cluster. Before we do that, there are a couple of things to understand.
By default, our Terraform templates are configured with the assumption that you have an SSH public key called id_rsa.pub in the .ssh folder of your home directory (along with a corresponding private key). Terraform uses this to authorize your key on the cluster nodes that it creates. This provides you with SSH access to the nodes which is required for the subsequent Ansible provisioning. The simplest way to handle this when running from a Docker container is to mount your ~/.ssh folder in the container. You will see an example of this later in the document.
Another important thing to understand is how Terraform manages state. Terraform uses a JSON formatted file to store the state of your managed infrastructure. This state file is important as it will allow you to use Terraform to plan, inspect, modify and destroy resources in your infrastructure. By default, Terraform writes state to a file called terraform.tfstate in the same directory where you launched Terraform. Our Dockerfile is configured to store the state in a Docker volume called /state. This will allow you to mount that volume so that you can easily access the terraform.tfstate file to use for future Terraform runs.
Now we can use this information to run our container:
docker run -it -v ~/.ssh/:/ssh/ -v $PWD:/state mi
As discussed above we are launching a container from the mi image we created earlier, while mounting our local ~/.ssh/ to /ssh in the container, and our current directory to the container’s /state. Therefore, the terraform.tfstate files will be accessible from our local host directory after the run. Note that we are also allocating a TTY for the container process (using -it) so that we can enter our SSH key passphrase if necessary.
The container should launch and provision the cluster using the security.yml, Terraform template, and custom playbook that you configured in the Setup above.
Note
If you have customized your Terraform template to use a different SSH public key than the default ~/.ssh/id_rsa.pub, you can specify the corresponding private key as an environment variable (SSH_KEY) when running the container. For example:
docker run -it -e SSH_KEY=/root/.ssh/otherpvtkey -v ~/.ssh/:/ssh/ -v $PWD:/state mi
