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How to Set Up a Basic Ubuntu 15.10 Server with SSH Access

This tutorial is an example of Literate Shell Scripting, which is a way of documenting shell scripts that was introduced in a blog post on labs.consol.de.

The example tutorial shows some basic steps for setting up a new Ubuntu 15.10 server with SSH access:

The remainder of this page shows how to automatically execute the code snippets from this tutorial using Packer.

Configuring the Automated Build

The example code in this tutorial can be executed using Packer. Packer is a tool for creating machine images for multiple platforms, like Amazon Web Services, Virtual Box, Digital Ocean, VMWare, Docker, etc. A Packer build is configured via a JSON file called template. The template for this tutorial is basic-ubuntu-server-setup.json.

In order to run the code snippets from this tutorial, we first need to download the tutorial from GitHub:

git clone https://github.com/ConSol/basic-ubuntu-server-setup

The template file uses environment variables to learn the name and the ssh public key of the user to be created. We need to export these variables before running the build (replace fabian with the user name and ssh-rsa XXX... with the ssh public key for the user):

export USER_NAME="fabian"
export SSH_KEY="ssh-rsa APUBLICSSHKEYISaLoNGStriNG..."

Last but not least, we need to install Packer. Packer is a single executable, so installing Packer boils down to putting the executable somewhere in the path. See Packer's installation instructions for more information. Alternatively, on machines with the Go programming language compiler installed, we can install Packer from source:

go get -u github.com/mitchellh/packer

How to Run the Build on Docker

We can use Packer to create a Docker container from the code snippets in the tutorial. The following command will create a file basic-ubuntu-server-setup.tar containing the Docker container.

packer build -only docker basic-ubuntu-server-setup.json

We can now import the container file and create a new Docker image from it:

docker import - consol/basic-ubuntu-server-setup:latest < basic-ubuntu-server-setup.tar

Now we can the image. Docker images don't start services automatically, so in order to test the ssh service, we need to explicitly pass service ssh start as the command when starting the container. Moreover, if we use docker-machine or boot2docker, we cannot access the Docker container directly, but we must forward the port through the Docker host. As the ssh port 22 on the Docker host is already in use, we map the port to 2222:

docker run -p 2222:22 -t -i consol/basic-ubuntu-server-setup /bin/bash -c 'service ssh start && exec /bin/bash'

Assuming the Docker host's address is 192.168.99.100 (on Linux it would be localhost instead), we should now be able to start a new shell window and connect to the Docker container:

ssh -p 2222 -l $USER_NAME 192.168.99.100

How to Run the Build on Digital Ocean

As an alternative to running this tutorial locally with Docker, we can run it on Digital Ocean, which is a simple, developer-friendly and reasonably-priced cloud service.

In order to use Digital Ocean from the command line, we need an API token. The API token can be retrieved from Digital Ocean's Web interface. After logging into the Web interface and navigating to the 'API' tab, there is a button labeled 'Generate New Token'.

Packer reads the API token from the DIGITALOCEAN_API_TOKEN environment variable, so we need to export that variable (replace the value 2d611... with your API token):

export DIGITALOCEAN_API_TOKEN=2d61116d42a12d860802fa9dfc06ed8aae3ff8187c923d7ac66b6e8823b2d456

To test if this works, we run an example API call using curl. The following command should retrieve a list of available images from Digital Ocean:

curl -X GET \
     -H "Content-Type: application/json" \
     -H "Authorization: Bearer ${DIGITALOCEAN_API_TOKEN}" \
     "https://api.digitalocean.com/v2/images?page=1&per_page=100"

If everything goes fine, we can run the code snippets from this tutorial on Digital Ocean using Packer:

packer build -only digitalocean basic-ubuntu-server-setup.json

After the successful run, a new image with the result will be available on Digital Ocean's web interface on the 'Images' tab. Clicking 'More' -> 'Create Droplet' will run that image.

How to Run the Build on Other Platforms

The builders configuration in basic-ubuntu-server-setup.json contain Docker as an example of a local build, and Digital Ocean as an example of a cloud service. However, it is perfectly possible to run the example an any other platform supported by Packer.

Packer's builders documentation shows how to configure the builders section for any supported platform.

Just as a side note: The Virtual Box configuration turns out to be quite complex, because we need to automate the graphical installation process after booting Ubuntu's ISO image. It is a good idea to get a working configuration from https://github.com/boxcutter/ubuntu and start from there.

TL;DR

This tutorial is an example of Literate Shell Scripting with Markdown and Packer, which is introduced here: labs.consol.de