Containers can be attached:
- after they are created, but before they are started
- after a successful deploy, but before the proxy reloads
This allows folks to have flexibility around when they would like a container to be made available to a network.
The IMAGE_TAG is not always available, while the IMAGE_SOURCE_TYPE is. Since the point of these triggers was to unify the argument passed and make it easier to interact with them, this version makes more sense.
Closes#3780
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 will allow background processes to cleanup these files if they were unable to be cleaned up during a run of the dokku binary, as is the case for files copied by the docker binary when running in docker.
This reduces duplication and allows users to rely on global arguments to generate most labels needed.
The 'commit' command cannot have global arguments because the whitespace within the label change breaks string-based interpolation, and shell arrays cannot be exported.
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.
