x add `opts required: [:api_key, [:user, :password]]`
x add opt '--foo', requires: :other
x add opt '--foo', alias: :other
x add opt '--foo', format: /.+/
x add opt '--foo', deprecated: true
x add opt '--foo', alias: :other, deprecated: :other
x add opt '--foo', max: 10, type: :integer
x add opt '--foo', enum: ['one', 'two']
x consider automatically adding `[no-]` to booleans
x make it so that Cl::Cmd parses the args, not Runner. only that way sub cmd specific opts can sit on the sub command
x cleanup and move matchers
x add lookup and interpolation to assert
x revisit using MSGS and CMDS everywhere
x add something like :keep for automatically moving things out of the way before cleanup
x make specs validate that cmds have run in the correct order
x revisit what's up with `needs_key`
x revisit what's up with `git_http_user_agent false`
x revisit the run stages in Provider
x implement folds
x port on-demand installation of sub gems
x make MSGS etc class methods, so they can inherit from base classes (for Heroku)
x move sub cmd opts etc to sub classes for Heroku
x look into using FakeFS, MemFS sucks
x make a list of strategies/tools providers use
x revisit which providers need an ssh key, git, etc.
x should have run in order matcher does not work
x write bin/readme
x test Cl against all Ruby versions >= 2.0
x test Ctx
x go through all providers, remove fakefs, use chdir 'tmp/dpl'
x make sure all provider fs write operations go through ctx
x what is `options[:no_deploy]` for? (it's for testing. added it back as `--stages`)
x make sure dasherized options are accepted and normalized
x add opt internal: true to Cl
x write comments on the most important classes, so we can generate some api docs
x install gems with sudo if Process::UID.eid is 0
x document Provider.env
x add retry to Ctx#script
x try installing all gems at once
x run apt-get update before apt-get install, once
x make sure failed dependency installation fails the command
x fix dependency installation for various providers
x look into making `--app` and `--key_name` attr readers, rather than options
x make it so that options are being overwritten if specified by both base and sub classes
x test that `bin/dpl --stage install` runs as expected for various providers
x on Travis CI add a stage that tests `bin/dpl --stage install` for various providers on various ruby versions
x try using bundler/inline for gem dependencies
x write a proper readme for Cl
x add yard docs to Cl
x autogenerate examples
x update .github/CONTRIBUTING.md
x consider adding `note: 'some comment` to Cl opts (e.g. see Lambda tracing mode)
x bundle/inline seems to pick up an existing Gemfile.lock (which might be incompatible)
x figure out how to deal with python tooling on non-python images etc (just die for now)
x unit test netlfiy
x move ./.dpl to ~/.dpl (clutters the working dir)
x add a DSL for adding paths to PATH, e.g. gcs
x make sure all error messages are actually being displayed
x remove the fold for finishing the deployment, it's confusing. Maybe do not fold the deployment itself? or somehow keep the last fold open if there is an error?
x BitBalloon is now Netlify Drop https://app.netlify.com/drop. time to rename it?
x make `--skip_cleanup` the default
x make sure all main shell scripts use assert: true, echo: true
x make sure all asserts have an err msg (can we test this?), or add a generic error message
x add secure: true, in order to tell Cl to filter log output for a given option
x refactor Provider by splitting out a Cmd class for shell commands
x document Cmd methods
x revisit README and CONTRIBUTING
x Make sure failed deployments always fail the build starting with dpl 2.0
x PR sf-datapipeline
x add a DSL for moving files out of the way, and moving them back later, e.g. gcs /etc/boto.cfg
x start a CHANGELOG.md?

- EY docs do not explain where to obtain the api key

Future improvements

- https://www.freecodecamp.org/news/how-to-deploy-your-cloud-foundry-app-with-almost-zero-fear-using-travis-ci-926697fff8f6/