2016-07-19 00:40:07 -04:00
|
|
|
<!--[metadata]>
|
|
|
|
|
+++
|
|
|
|
|
title = "Keep containers alive during daemon downtime"
|
|
|
|
|
description = "How to keep containers running when the daemon isn't available."
|
|
|
|
|
keywords = ["docker, upgrade, daemon, dockerd, live-restore, daemonless container"]
|
|
|
|
|
[menu.main]
|
|
|
|
|
parent = "engine_admin"
|
|
|
|
|
weight="6"
|
|
|
|
|
+++
|
|
|
|
|
<![end-metadata]-->
|
|
|
|
|
|
|
|
|
|
# Keep containers alive during daemon downtime
|
|
|
|
|
|
|
|
|
|
By default, when the Docker daemon terminates, it shuts down running containers.
|
|
|
|
|
Starting with Docker Engine 1.12, you can configure the daemon so that containers remain
|
|
|
|
|
running if the daemon becomes unavailable. The live restore option helps reduce
|
|
|
|
|
container downtime due to daemon crashes, planned outages, or upgrades.
|
|
|
|
|
|
|
|
|
|
## Enable the live restore option
|
|
|
|
|
|
|
|
|
|
There are two ways to enable the live restore setting to keep containers alive
|
|
|
|
|
when the daemon becomes unavailable:
|
|
|
|
|
|
|
|
|
|
* If the daemon is already running and you don't want to stop it, you can add
|
|
|
|
|
the configuration to the daemon configuration file. For example, on a linux
|
|
|
|
|
system the default configuration file is `/etc/docker/daemon.json`.
|
|
|
|
|
|
|
|
|
|
Use your favorite editor to enable the `live-restore` option in the
|
|
|
|
|
`daemon.json`.
|
|
|
|
|
|
|
|
|
|
```bash
|
|
|
|
|
{
|
|
|
|
|
"live-restore": true
|
|
|
|
|
}
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
You have to send a `SIGHUP` signal to the daemon process for it to reload the
|
|
|
|
|
configuration. For more information on how to configure the Docker daemon using
|
2016-08-03 12:51:09 -04:00
|
|
|
config.json, see [daemon configuration file](../reference/commandline/dockerd.md#daemon-configuration-file).
|
2016-07-19 00:40:07 -04:00
|
|
|
|
|
|
|
|
* When you start the Docker daemon, pass the `--live-restore` flag:
|
|
|
|
|
|
|
|
|
|
```bash
|
|
|
|
|
$ sudo dockerd --live-restore
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
## Live restore during upgrades
|
|
|
|
|
|
|
|
|
|
The live restore feature supports restoring containers to the daemon for
|
|
|
|
|
upgrades from one minor release to the next. For example from Docker Engine
|
|
|
|
|
1.12.1 to 1.13.2.
|
|
|
|
|
|
|
|
|
|
If you skip releases during an upgrade, the daemon may not restore connection
|
|
|
|
|
the containers. If the daemon is unable restore connection, it ignores the
|
|
|
|
|
running containers and you must manage them manually. The daemon won't shut down
|
|
|
|
|
the disconnected containers.
|
|
|
|
|
|
|
|
|
|
## Live restore upon restart
|
|
|
|
|
|
|
|
|
|
The live restore option only works to restore the same set of daemon options
|
|
|
|
|
as the daemon had before it stopped. For example, live restore may not work if
|
|
|
|
|
the daemon restarts with a different bridge IP or a different graphdriver.
|
|
|
|
|
|
|
|
|
|
## Impact of live restore on running containers
|
|
|
|
|
|
|
|
|
|
A lengthy absence of the daemon can impact running containers. The containers
|
|
|
|
|
process writes to FIFO logs for daemon consumption. If the daemon is unavailable
|
|
|
|
|
to consume the output, the buffer will fill up and block further writes to the
|
|
|
|
|
log. A full log blocks the process until further space is available. The default
|
|
|
|
|
buffer size is typically 64K.
|
|
|
|
|
|
|
|
|
|
You must restart Docker to flush the buffers.
|
|
|
|
|
|
|
|
|
|
You can modify the kernel's buffer size by changing `/proc/sys/fs/pipe-max-size`.
|
|
|
|
|
|
|
|
|
|
## Live restore and swarm mode
|
|
|
|
|
|
|
|
|
|
The live restore option is not compatible with Docker Engine swarm mode. When
|
|
|
|
|
the Docker Engine runs in swarm mode, the orchestration feature manages tasks
|
|
|
|
|
and keeps containers running according to a service specification.
|
