Signal systemd when we start shutting down to complement the "READY" notify
that was originally implemented in 97088ebef7
From [sd_notify(3)](https://www.freedesktop.org/software/systemd/man/sd_notify.html#STOPPING=1)
> STOPPING=1
> Tells the service manager that the service is beginning its shutdown. This is useful
> to allow the service manager to track the service's internal state, and present it to
> the user.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Files that are suffixed with `_linux.go` or `_windows.go` are
already only built on Linux / Windows, so these build-tags
were redundant.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
This patch introduces a new experimental engine-level plugin management
with a new API and command line. Plugins can be distributed via a Docker
registry, and their lifecycle is managed by the engine.
This makes plugins a first-class construct.
For more background, have a look at issue #20363.
Documentation is in a separate commit. If you want to understand how the
new plugin system works, you can start by reading the documentation.
Note: backwards compatibility with existing plugins is maintained,
albeit they won't benefit from the advantages of the new system.
Signed-off-by: Tibor Vass <tibor@docker.com>
Signed-off-by: Anusha Ragunathan <anusha@docker.com>
