How to Restart Docker

In this article, you will learn how to restart the Docker daemon and Docker containers using the CLI.
For this guide, we'll use a BlueVPS NVMe-bKVM server with 4 GB of RAM.
We assume that you run all commands as the root user.

Should you restart the Docker daemon or a Docker container?

Restart the Docker daemon when you have updated the Docker Engine or system kernel; the Docker CLI isn't responding (frozen), you changed /etc/docker/daemon.json settings (e. g., storage drivers, log drivers or custom registries).

Restart a Docker container when an app inside the container has frozen/lagged/crashed; you changed an app config file or mounted volume files for the container.

Restart the Docker Daemon

To restart Docker, simply run the following command:

Please note that systemctl restart docker will restart all your running containers by default. You can verify it using this command:

But if the output shows Live Restore Enabled: true which is not a default setting, your containers will stay alive.
Use this command to enable live restore (containers will stay alive if the daemon restarts):

tee /etc/docker/daemon.json <<EOF
{
 "live-restore": true
}
EOF
systemctl reload docker

tee /etc/docker/daemon.json <<EOF
{
 "live-restore": false
}
EOF
systemctl reload docker

Restart a Docker container

Before restarting a container you should identify its name or ID. Run the following command to list your containers:

Here we can see 3 of our containers, we can restart them by using CONTAINER ID or NAMES.
For example, let's restart httpd by its name and then by its container ID:

From the status we can see that the container was restarted and has been running for one second now

Restart a container automatically

Docker has restart policies for containers on exit or when Docker restarts so you avoid using process managers to start containers.
There are four restart policies:

no - Don't restart the container.
on-failure[:max-retries] - Restart the container on failure, you can limit the number of restart attempts.
always - Always restart the container when it stops.
unless-stopped- Always restart the container if it stops, unless you stopped it manually.

Here are command examples for all four restart policies:

docker run -d --restart=no httpd
docker run -d --restart=on-failure:3 httpd
docker run -d --restart=always httpd
docker run -d --restart=unless-stopped httpd

Conclusion

Knowing when and how to restart Docker containers can save time and prevent unnecessary downtime:

• Use systemctl restart docker for core updates and configuration changes.
• Use docker restart <name/ID> to quickly recover a specific unresponsive application.
• Set appropriate restart policies (--restart) during deployment to automate container recovery.

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