Upcoming changes in CLI

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As part of CEKit 3.0 development we spend some time on reviewing existing 2.x code. Many areas were identified where an of improvements were identified and some of them were already adjusted! We plan series of blog posts about most important changes that will be part of CEKit 3.0. This is the first one.

One of the parts that was under heavy review was the CLI itself. We found that the CLI was bloated and the usage was not clear at all.

The CLI was redesigned from scratch. We switched from argparse to Click which provides much cleaner definition of commands. This one change triggered a fairly massive rewrite of the codebase. Yes, this PR contains a few other things, but nonetheless it’s huge :)

New CLI overview

New CLI besides being a complete rewrite of the old one, introduces many changes. You will find that the usage differs from what you are used to.

Parameters are grouped with commands

This means that you can set only these parameters that are available for the command you execute and not others. In previous version you could set anything anywhere. While it was handy (you did not care about the order) it was very hard to understand what you can set for particular command and which parameters were actually ignored!

With this rewrite when you define a parameter you need to know where it belongs to:

# This is correct
$ cekit -v build --overrides '{"from": "centos:6"}' docker
# This is wrong!
$ cekit -v build docker --overrides '{"from": "centos:6"}'

The second way of defining overrides is wrong, because the --overrides parameter belongs o the build command and not to the docker builder command.

The generate phase was replaced with --dry-run switch

If you used previously the cekit generate command, it will not work anymore. You need to use the --dry-run switch from the build command:

$ cekit build --dry-run docker
2019-03-12 11:11:59,826 cekit        WARNING  You are running unreleased development version of CEKit, use it only at your own risk!
2019-03-12 11:11:59,826 cekit        INFO     You are running on known platform: Fedora 29 (Twenty Nine)
2019-03-12 11:11:59,863 cekit        INFO     Generating files for docker engine
2019-03-12 11:11:59,863 cekit        INFO     Initializing image descriptor...
2019-03-12 11:11:59,869 cekit        INFO     Rendering Dockerfile...
2019-03-12 11:11:59,905 cekit        INFO     The --dry-run parameter was specified, build will not be executed
2019-03-12 11:11:59,905 cekit        INFO     Finished!

Preparation for different test frameworks

Just like we have multiple builders, the test command is now prepared to support different test frameworks. At this moment we support only Behave, but maybe in the future we will add more.

Built-in help

The CLI has now a built-in help, if you are unsure how to execute something, make good use of the --help parameter. This will print you all available options as well as usage instructions, if available.

$ cekit test behave --help
Usage: cekit test behave [OPTIONS]

  DESCRIPTION

      Execute Behave container image tests locally using Docker

      NOTE: Image to test must be available in the Docker daemon. It won't be pulled
      automatically!

  EXAMPLES

      Execute tests for the example/app:1.0 image

          $ cekit test --image example/app:1.0 behave

[SNIP]

Summary

Although the change is big we hope you will get used to the new CLI. If you have any comments about this change, let us know!

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