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<!--[metadata]>
+++
title = "Apply rolling updates"
description = "Apply rolling updates to a service on the Swarm"
keywords = ["tutorial, cluster management, swarm, service, rolling-update"]
[menu.main]
identifier="swarm-tutorial-rolling-update"
parent="swarm-tutorial"
weight=20
advisory = "rc"
+++
<![end-metadata]-->
# Apply rolling updates to a service
In a previous step of the tutorial, you [scaled](scale-service.md) the number of
instances of a service. In this part of the tutorial, you deploy a new Redis
service and upgrade the service using rolling updates.
1. If you haven't already, open a terminal and ssh into the machine where you
run your manager node. For example, the tutorial uses a machine named
`manager1`.
2. Deploy Redis 3.0.6 to all nodes in the Swarm and configure
the swarm to update one node every 10 seconds:
```bash
$ docker service create --scale 3 --name redis --update-delay 10s --update-parallelism 1 redis:3.0.6
8m228injfrhdym2zvzhl9k3l0
```
You configure the rolling update policy at service deployment time.
The `--update-parallelism` flag configures the number of service tasks
to update simultaneously.
The `--update-delay` flag configures the time delay between updates to
a service task or sets of tasks. You can describe the time `T` in the number
of seconds `Ts`, minutes `Tm`, or hours `Th`. So `10m` indicates a 10 minute
delay.
3. Inspect the `redis` service:
```
$ docker service inspect redis --pretty
ID: 75kcmhuf8mif4a07738wttmgl
Name: redis
Mode: REPLICATED
Scale: 3
Placement:
Strategy: SPREAD
UpateConfig:
Parallelism: 1
Delay: 10s
ContainerSpec:
Image: redis:3.0.6
```
4. Now you can update the container image for `redis`. Swarm applies the update
to nodes according to the `UpdateConfig` policy:
```bash
$ docker service update --image redis:3.0.7 redis
redis
```
5. Run `docker service inspect --pretty redis` to see the new image in the
desired state:
```
docker service inspect --pretty redis
ID: 1yrcci9v8zj6cokua2eishlob
Name: redis
Mode: REPLICATED
Scale: 3
Placement:
Strategy: SPREAD
UpdateConfig:
Parallelism: 1
Delay: 10s
ContainerSpec:
Image: redis:3.0.7
```
6. Run `docker service tasks TASK-ID` to watch the rolling update:
```
$ docker service tasks redis
ID NAME SERVICE IMAGE DESIRED STATE LAST STATE NODE
5409nu4crb0smamziqwuug67u redis.1 redis redis:3.0.7 RUNNING RUNNING 21 seconds worker2
b8ezq58zugcg1trk8k7jrq9ym redis.2 redis redis:3.0.7 RUNNING RUNNING 1 seconds worker1
cgdcbipxnzx0y841vysiafb64 redis.3 redis redis:3.0.7 RUNNING RUNNING 11 seconds worker1
```
Before Swarm updates all of the tasks, you can see that some are running
`redis:3.0.6` while others are running `redis:3.0.7`. The output above shows
the state once the rolling updates are done. You can see that each instances
entered the `RUNNING` state in 10 second increments.
Next, learn about how to [drain a node](drain-node.md) in the Swarm.
<p style="margin-bottom:300px"> </p>
|
