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consist

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THIS IS BETA SOFTWARE UNDER ACTIVE DEVELOPMENT. APIs AND FEATURES WILL CHANGE.

consist - (noun): a set of railroad vehicles forming a complete train.

consist is the one person framework server scaffolder. It is stone age tech.

You can use it to quickly baseline a raw server using a given recipe provided by Consist. I use it to baseline new Droplets to be ready to run Kamal in single server setup for a Rails monolith. While Kamal will setup Docker for you, it does not do anything else related to configuring the underlying server, such as firewalls, general hardening, enabling swapfile etc.

Project Principles

  • Minimal tool specific language / knowledge required to use Consist
  • Procedural declaration execution - no converging, orchestration or event driven operation
  • If you can shell script it, you can consist it directly
  • Encouraging sharing of portable Consistfiles across the community

Quick start

Make sure the consist gem is installed:

gem install consist

You must be already authenticated with the server you want to scaffold. consist will use your account's SSH id to perform actions.

The main way of using consist is to go with a Consistfile in your project root that describes the recipe and steps. Then you can say:

consist up <ip_address> [--consistfile=/path/to/consistfile] [--consistdir=/path/to/.consistdir]

And consist will do it's thing with that given IP address.

To create a blank Consistfile in your project, execute:

consist init

Commands

Other commands available:

  • consist init [account/repo] - initialize your project with a new Consist file. Optionally, you can specify a Github account/repo path and that location will be used to clone down a Consistfile, and any associated artifacts needed by the Consistfile.
  • consist ping <ip_address> - checks you can connect and authenticate with the given IP

Features

  • Simple Ruby based DSL
  • ERB interpolation of config on shell commands and file contents
  • Small API surface area - quick to learn

Rationale

I wanted a super-simple tool, that was baked in Ruby, for setting up random servers to specific configurations. This is the result.

On a scale of 1 to 10, with 10 being Terraform, this tool is basically as low-rent you can get to hand running scripts yourself, so about a 3 on the scale.

If you know how to shell script what you want, you can stick it in a step, and add it to a recipe.

The more I work in this industry, the less I see using other people's code and tools as a benefit, and more of a liability. I appreciate the paradox I'm creating here for you 😅

Why not use Terraform / Ansible / Salt etc?

I think they are bad tools for my needs. I wanted something simple I could hack on, grow only when needed, and will work specifically without ambiguity. For example, Ansible has a lot of nonsense with case sensitivity, Terraform does weird unexpected things.

I didn't want to keep maintaining specific knowledge of these infrastructure as code tools in my brain anymore, along with all of their peculiarities and oddities.

If you prefer those tools, go ahead and use them.

Ain't nobody stopping you.

Key Concepts

Consist leans on three primary ideas: recipes, steps and files. Recipes contain one or more steps. Steps tend to be atomic and idempotent.

Recipes

Example of a recipe:

name "Kamal Single Server"
description "Sets up a single server to run Kamal"
user :root

steps do
  step :update_apt_packages
  step :install_apt_packages
end

Steps

Example of a step:

name "Install APT packages"
required_user :root

shell "Installing essential packages" do
  <<~EOS
    apt-get -y remove systemd-timesyncd
    timedatectl set-ntp no
    apt-get -y install build-essential curl fail2ban git ntp vim
    apt-get autoremove
    apt-get autoclean
  EOS
end

shell "Start NTP and Fail2Ban" do
  <<~EOS
    service ntp restart
    service fail2ban restart
  EOS
end

Files

Example of a file:

file :hostname do
  <<~EOS
  <%= hostname %>
  EOS
end

Consistfile

A Consistfile is a portable giant file of a recipe and all its steps. Something like (this is a full example, in practice you would reference some of Consists' built in steps):

# This is a shortened non-complete example.
consist do
  config :hostname, "testexample.com"
  config :site_fqdn, "textexample.com"
  config :admin_email, "[email protected]"
  config :swap_size, "2G"
  config :swap_swappiness, "60"
  config :timezone, "UTC"

  file :apt_auto_upgrade do
    <<~EOS
      APT::Periodic::AutocleanInterval "7";
      APT::Periodic::Update-Package-Lists "1";
      APT::Periodic::Unattended-Upgrade "1";
    EOS
  end

  file :hostname do
    <<~EOS
      <%= hostname %>
    EOS
  end

  file :timezone do
    <<~EOS
      <%= timezone %>
    EOS
  end

  recipe :kamal_single_server do
    name "Kamal Single Server Scaffold"

    steps do
      step :set_hostname do
        upload_file message: "Setting hostname",
          local_file: :hostname,
          remote_path: "/etc/hostname"

        shell do
          <<~EOS
            hostname <%= Consist.config[:hostname] %>
          EOS
        end

        mutate_file mode: :replace, target_file: "/etc/hosts", match: "^127.0.0.1 localhost$",
          target_string: "127.0.0.1 localhost <%= hostname %>"
      end

      step :setup_timezone do
        shell do
          <<~EOS
            rm /etc/localtime
          EOS
        end

        upload_file message: "Setting Timezone",
          local_file: :timezone,
          remote_path: "/etc/timezone"

        shell do
          <<~EOS
            chmod 0644 /etc/timezone
            ln -s /usr/share/zoneinfo/<%= timezone %> /etc/localtime
            chmod 0644 /etc/localtime
            DEBIAN_FRONTEND=noninteractive dpkg-reconfigure -f noninteractive tzdata
          EOS
        end
      end
    end
  end
end

# vim: filetype=ruby

Given a Consistfile you could then say consist up <ip_address> and it would just work.

Artifacts

Artifacts allow you to split out your Consistfile into separate files.

You can create blocks in the Consistfile as shown above, but you can also only specify an id, and that id will be used to try and attempt to load a file of that name in the .consist/<type>/<id> directory. For example, referencing a file:

file :apt_auto_upgrade

Will attempt to load a file in .consist/files/apt_auto_upgrade. The same is possible for any of the main types: files, steps, and recipes

.consist directory

The .consist directory is assumed to be in the root of your project, and should contain three subdirectories for each of the types: files, steps, recipes.

You can specify an alternate directory location by passing the --consistdir switch to the up command.

Community Consistfiles

If you create a Github repo, and all it contains is a Consistfile and any associated artifacts under a .consist directory, other people will be able to use it by executing consist init <gh_repo_path> in their project root.

If you create one, please open a PR to include it here:

Name Repo Description
Kamal Single Server Setup consist-sh/kamal-single-server Setup a single server with good defaults ready to run Kamal

Is it good?

I think so. But I don't know, use your own brain or something. Don't listen to me.

Support

If you want to report a bug, or have ideas, feedback or questions about the gem, let me know via GitHub issues and I will do my best to provide a helpful answer.

License

The gem is available as open source under the terms of the LGPLv3 License.

Code of conduct

Everyone interacting in this project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.

Contribution guide

Pull requests are welcome, but I want you to open an Issue first to discuss your ideas. Thanks.

Development

  1. Clone the repo
  2. Run bundle install
  3. Run bin/dev to execute consist locally without having to build and install.

Make sure any PRs have been formatted with standard.