Dockit

Dockit is an alternative composer for docker projects. Its (IMHO) advantage is that it is scriptable, and rather than a single yaml configuration file, each service has it's own configuration file (Dockit.yaml), as well as an optional Dockit.rb which can provide scriptable configuration (as Thor subcommands) for any phase of the build and deploy process.

Dockit is built on the Thor cli and the docker-api libraries.

$ gem install dockit

1. Create a top level deployment directory
2. Create a sub-directory for each service
3. Create a Dockit.yaml for each service (and optionally a Docit.rb.)
4. Optionally, create a top level Dockit.rb subcommand file to orchestrate the build and deployment of the services.
5. Run dockit in the root directory for help.

The sections of the config file map directly to the argument sent by the docker-api to the corresponding api endpoints (see docker api.)

The top level sections are:

• build
• create
• run

At least one of the sections build or create are required. If their is no build section, the create section must specify an Image value. Note that most (all?) of the values specified in the run section can be specified in the create: HostConfig: instead.

build:
  t: my-image

Executing dockit build in the directory containing the file above, will create an image from the Dockerfile in the same directory named my-image.

Then executing dockit start will create and run a container named my-image

create:
  Image: postgres
  name: db

Executing dockit build will do nothing. Executing dockit start will start run a container named db from the local (or docker hub postgresql image.

The yaml file is first processed by the ERB template library. The "bindings" passed to the template processor can be specified on the command line with the --locals (alias -l) option. Also, the command line option --env (alias -e) is passed as -<env> For example, given:

create:
  Image: postgres
  name: db<%= env %>
  Env:
  - MYVAR=<%= myval %>

• dockit start will generate an error (myval not defined)
• dockit start -l myval:foo will start a container named db with the environment variable MVAR set to foo.
• dockt start -l myval:foo -e test will start a container named db-test

The dockit.rb file can be used to add new subcommands to the cli on a project-wide or per-service basis. For per-service subcommands, the defined class name should be the "classified" directory name, for the project-wide, it should be named All. If the class inherits from SubCommand instead of Thor, it will inherit two useful methods:

• invoke_default(service) will run the same-named (or specified) dockit command on the specified service.
• invoke_service(service) will run the same-named (or specifed) subcommand from the Dockit.rb for the specified service.
• invoke_git(service) will run the same-name (or specifed) subcommand from the Dockit.rb for the specified service after checking out the git repository for the service as a gzip archive to repos.tar.tz. By default it used the master branch. Note that the repos key must be set in the services yaml file.

For example:

class All < SubCommand
  desc 'build', 'build all images'
  def build
    invoke_service 'app'
    invoke_default 'db'
  end
end

Would run the build method from the file app/Dockit.rb and then create a second image using the options from db/Dockit.yaml.

If the droplet_kit gem is found at runtime, the do service be implemented. see dockit help do for available commands.

If you don't want to install ruby, etc., the docker image is also available rom docker hub as cybercode/dockit. You can create your own version of the docker image from the source code with docker build -t dockit . (or rake docker). The Dockerfile has dockit as the entrypoint, so you can pass dockit arguments on the command-line. e.g.:

docker run --rm -v /var/run/docker.sock:/var/run/docker.sock -v $PWD:/app dockit help

After checking out the repo, run bin/setup to install dependencies. Then, run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release to create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

1. Fork it ( https://github.com/cybercode/dockit/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am [comment])
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request