Tomo

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Tomo is a friendly command-line tool for deploying Rails apps. It is a new alternative to Capistrano, Mina, and Shipit that aims for simplicity and developer happiness.

๐Ÿ’ป Rich command-line interface with built-in bash completions
โ˜๏ธ Multi-environment and role-based multi-host support
๐Ÿ’Ž Everything you need to deploy a basic Rails app out of the box
๐Ÿ”Œ Easily extensible for polyglot projects (not just Rails!)
๐Ÿ’ก Concise, helpful error messages
๐Ÿ“š Quality documentation
๐Ÿ”ฌ Minimal dependencies

See how tomo compares to other Ruby deployment tools.


Quick start

Tomo is distributed as a ruby gem. To install:

$ gem install tomo

For instructions on setting up bash completions, run:

$ tomo completion-script

Configuring a project

Tomo is configured via a .tomo/config.rb file in your project. To get started, you can use tomo init to generate a configuration that works for a basic Rails app.

$ tomo init

An abbreviated version looks like this:

# .tomo/config.rb

plugin "git"
plugin "bundler"
plugin "rails"
# ...

host "user@hostname.or.ip.address"

set application: "my-rails-app"
set deploy_to: "/var/www/%{application}"
set git_url: "git@github.com:my-username/my-rails-app.git"
set git_branch: "master"
# ...

setup do
  run "git:clone"
  run "git:create_release"
  run "bundler:install"
  run "rails:db_schema_load"
  # ...
end

deploy do
  run "git:create_release"
  run "core:symlink_shared"
  run "core:write_release_json"
  run "bundler:install"
  run "rails:assets_precompile"
  run "rails:db_migrate"
  run "core:symlink_current"
  # ...
end

Check out the configuration docs for a complete reference.

Usage

Tomo gives you easy-to-use commands for three common use cases:

  1. tomo setup prepares a remote host for its first deploy
  2. tomo deploy performs a deployment
  3. tomo run lets you invoke one-off tasks

Setup

tomo setup prepares the remote host for its first deploy by sequentially running the setup list of tasks specified in .tomo/config.rb. These tasks typically create directories, initialize data stores, install prerequisite tools, and perform other one-time actions that are necessary before a deploy can take place.

Out of the box, tomo will:

  • Configure necessary environment variables, like RAILS_ENV and SECRET_KEY_BASE
  • Install Ruby, Bundler, Node, Yarn, and dependencies
  • Create all necessary deployment directories
  • Create the Rails database, load the schema, and insert seed data

Deploy

Whereas tomo setup is typically run once, you can use tomo deploy every time you want to deploy a new version of your app. The deploy command will sequentially run the deploy list of tasks specified in .tomo/config.rb. You can customize this list to meet the needs of your app. By default, tomo runs these tasks:

  1. Create a release (using the git:create_release task)
  2. Build the project (e.g. bundler:install, rails:assets_precompile)
  3. Migrate data to the meet the requirements of the new release (e.g. rails:db_migrate)
  4. Make the new release the “current” one (core:symlink_current)
  5. Restart the app to use the new current release (e.g. puma:restart)
  6. Perform any cleanup (e.g. bundler:clean)

Run

Tomo can also run individual remote tasks on demand. You can use the tasks command to see the list of tasks tomo knows about.

$ tomo tasks

One of the built-in Rails tasks is rails:console, which brings up a fully-interactive Rails console over SSH.

$ tomo run rails:console

Extending tomo

Tomo has many plugins built-in, but you can easily add your own to extend tomo with custom tasks. By convention, custom plugins are stored in .tomo/plugins/. These plugins can define tasks as plain ruby methods. For example:

# .tomo/plugins/my-plugin.rb

def hello
  remote.run "echo", "hello", settings[:application]
end

Use remote.run to execute shell scripts on the remote host, similar to how you would use Ruby’s system. Project settings are accessible via settings, which is a plain Ruby hash.

Load your plugin in config.rb like this:

# .tomo/config.rb

plugin "./plugins/my-plugin.rb"

And run it!

$ tomo run my-plugin:hello

Read the Writing Custom Tasks tutorial for an in-depth guide to extending tomo.

Tutorials

Reference documentation

FAQ

What does the unsupported option "accept-new" error mean?

By default, tomo uses the “accept-new” value for the StrictHostKeyChecking option, which is supported by OpenSSH 7.6 and newer. If you are using an older version, this will cause an error. As a workaround, you can override tomo’s default behavior like this:

# Replace "accept-new" with something compatible with older versions of SSH
set ssh_strict_host_key_checking: true # or false

Can I deploy multiple apps to a single host?

Tomo relies on the host user’s bash profile for various things, like setting environment variables and initializing rbenv and nodenv. This makes it impractical to deploy multiple apps to a single host using the same deploy user.

The solution is to create multiple users on the remote host, and then configure a different user for deploying each app. That way each user can have its own distinct environment variables and you can easily configure each app differently without risking conflicts. Refer to the tomo Rails tutorial for instructions on creating a deploy user.

E.g. app1 would be configured to deploy as:

host "app1@example.com"

And app2 would be configured to deploy as:

host "app2@example.com"

Next run tomo setup for both apps; this will set everything up for both users on the remote host (environment variables, rbenv, etc.). You can now deploy both apps to the same host, with the confidence that their configurations will be kept cleanly separated.

Support

This project is a labor of love and I can only spend a few hours a week maintaining it, at most. If you’d like to help by submitting a pull request, or if you’ve discovered a bug that needs my attention, please let me know. Check out CONTRIBUTING.md to get started. Happy hacking! โ€”Matt

License

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

Code of conduct

Everyone interacting in the Tomo projectโ€™s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.

Contribution guide

Interested in filing a bug report, feature request, or opening a PR? Excellent! Please read the short CONTRIBUTING.md guidelines before you dive in.