This PR uses the new syntax for commands introduced in Docker 1.13, making it a bit easier to understand just what a particular command is trying to do.
This also pushes the long-form syntax for docker command flags, which are also easier to understand at a glance.
This change allows operators to specify a DOCKER_BIN environment variable. This will specify a binary to run when executing docker, which is useful in cases where the 'docker' command being run must be modified in a way that would otherwise be invasive to Dokku, but minimalistic if done within a wrapper.
A DOKKU_SCALE file will always be used for managing the scale count for an app if it exists in a repository. As such, ps:scale usage should be disabled in those cases. This commit makes that more apparent.
Also document how to build a specific core plugin for testing purposes.
Closes#3544
While I do not agree with _every_ style change, this will force Dokku to have consistent formatting across all shell scripts, which is arguably a Good Thing™.
The command used to reprocess everything is:
```shell
shfmt -l -bn -ci -i 2 -w .
```
Often-times, we will want to have the container inspect output for debugging purposes, but this process is:
- error prone, as the user needs to know what their containers are
- potentially insecure, as the output must be sanitized of sensitive data
Instead of making users wade through this process, we provide a helper `ps:inspect` command, that can be used to diagnose problems associated with containers that may or may not exist for an application.
This will allow us to _actually_ introspect on the running state of an application. In certain cases, the detected state can be "mixed", meaning that we may need to take action, depending on what we want to do in mixed mode.
This allows users to quickly show the state of any configured application, as well as the state of their server. In doing so, we make it easy for them to provide information necessary for debugging in a single command.
