systemd: add support for reloading daemon configuration through systemd

This adds support for reloading the docker daemon
(SIGHIUP) so that changes in '/etc/docker/daemon.json'
can be loaded at runtime by reloading the service
through systemd ('systemctl reload docker')

Before this change, systemd would output an error
that "reloading" is not supported for the docker
service;

  systemctl reload docker
  Failed to reload docker.service: Job type reload is not applicable for unit docker.service.

After this change, the docker daemon can be reloaded
through 'systemctl reload docker', which reloads
the configuration;

  journalctl -f -u docker.service

  May 02 03:49:20 testing systemd[1]: Reloading Docker Application Container Engine.
  May 02 03:49:20 testing docker[28496]: time="2016-05-02T03:49:20.143964103-04:00" level=info msg="Got signal to reload configuration, reloading from: /etc/docker/daemon.json"
  May 02 03:49:20 testing systemd[1]: Reloaded Docker Application Container Engine.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 3e1b508e5f70b35869d9c8417d3b65a141820af9)
Signed-off-by: Eli Uriegas <eli.uriegas@docker.com>
Upstream-commit: 127426fc693a882b670339391da5d12f08c1438d
Component: packaging
This commit is contained in:
Sebastiaan van Stijn
2018-09-04 14:56:45 +00:00
committed by Eli Uriegas
parent 350162b4b0
commit 2e215339a1
@@ -13,6 +13,7 @@ ExecStartPre=/usr/libexec/containerd-offline-installer /var/lib/containerd-offli
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
ExecStart=/usr/bin/dockerd
ExecReload=/bin/kill -s HUP $MAINPID
ExecStopPost=/usr/bin/dockerd post-stop
TimeoutSec=0
RestartSec=2