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Signed-off-by: Charles Smith <charles.smith@docker.com>
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Charles Smith 2016-09-08 12:10:04 -07:00
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111
docs/reference/commandline/service_create.md
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@ -48,8 +48,8 @@ Options:
-w, --workdir string Working directory inside the container -w, --workdir string Working directory inside the container
``` ```
Creates a service as described by the specified parameters. This command has to Creates a service as described by the specified parameters. You must run this
be run targeting a manager node. command on a manager node.
## Examples ## Examples
@ -64,10 +64,10 @@ ID NAME REPLICAS IMAGE COMMAND
dmu1ept4cxcf redis 1/1 redis:3.0.6 dmu1ept4cxcf redis 1/1 redis:3.0.6
``` ```
### Create a service with 5 tasks ### Create a service with 5 replica tasks (--replicas)
You can set the number of tasks for a service using the `--replicas` option. The Use the `--replicas` flag to set the number of replica tasks for a replicated
following command creates a `redis` service with `5` tasks: service. The following command creates a `redis` service with `5` replica tasks:
```bash ```bash
$ docker service create --name redis --replicas=5 redis:3.0.6 $ docker service create --name redis --replicas=5 redis:3.0.6
@ -75,12 +75,12 @@ $ docker service create --name redis --replicas=5 redis:3.0.6
``` ```
The above command sets the *desired* number of tasks for the service. Even The above command sets the *desired* number of tasks for the service. Even
though the command returns directly, actual scaling of the service may take though the command returns immediately, actual scaling of the service may take
some time. The `REPLICAS` column shows both the *actual* and *desired* number some time. The `REPLICAS` column shows both the *actual* and *desired* number
of tasks for the service. of replica tasks for the service.
In the following example, the desired number of tasks is set to `5`, but the In the following example the desired state is `5` replicas, but the current
*actual* number is `3` number of `RUNNING` tasks is `3`:
```bash ```bash
$ docker service ls $ docker service ls
@ -88,8 +88,8 @@ ID NAME REPLICAS IMAGE COMMAND
4cdgfyky7ozw redis 3/5 redis:3.0.7 4cdgfyky7ozw redis 3/5 redis:3.0.7
``` ```
Once all the tasks are created, the actual number of tasks is equal to the Once all the tasks are created and `RUNNING`, the actual number of tasks is
desired number: equal to the desired number:
```bash ```bash
$ docker service ls $ docker service ls
@ -97,10 +97,8 @@ ID NAME REPLICAS IMAGE COMMAND
4cdgfyky7ozw redis 5/5 redis:3.0.7 4cdgfyky7ozw redis 5/5 redis:3.0.7
``` ```
### Create a service with a rolling update policy ### Create a service with a rolling update policy
```bash ```bash
$ docker service create \ $ docker service create \
--replicas 10 \ --replicas 10 \
@ -110,10 +108,12 @@ $ docker service create \
redis:3.0.6 redis:3.0.6
``` ```
When this service is [updated](service_update.md), a rolling update will update When you run a [service update](service_update.md), the scheduler updates a
tasks in batches of `2`, with `10s` between batches. maximum of 2 tasks at a time, with `10s` between updates. For more information,
refer to the [rolling updates
tutorial](../../swarm/swarm-tutorial/rolling-update.md).
### Setting environment variables (-e --env) ### Set environment variables (-e, --env)
This sets environmental variables for all tasks in a service. For example: This sets environmental variables for all tasks in a service. For example:
@ -121,7 +121,7 @@ This sets environmental variables for all tasks in a service. For example:
$ docker service create --name redis_2 --replicas 5 --env MYVAR=foo redis:3.0.6 $ docker service create --name redis_2 --replicas 5 --env MYVAR=foo redis:3.0.6
``` ```
### Set metadata on a service (-l --label) ### Set metadata on a service (-l, --label)
A label is a `key=value` pair that applies metadata to a service. To label a A label is a `key=value` pair that applies metadata to a service. To label a
service with two labels: service with two labels:
@ -137,19 +137,22 @@ $ docker service create \
For more information about labels, refer to [apply custom For more information about labels, refer to [apply custom
metadata](../../userguide/labels-custom-metadata.md). metadata](../../userguide/labels-custom-metadata.md).
### Set service mode ### Set service mode (--mode)
You can set the service mode to "replicated" (default) or to "global". A You can set the service mode to "replicated" (default) or to "global". A
replicated service runs as many tasks as specified, while a global service replicated service runs the number of replica tasks you specify. A global
runs on each active node in the swarm. service runs on each active node in the swarm.
The following command creates a "global" service: The following command creates a "global" service:
```bash ```bash
$ docker service create --name redis_2 --mode global redis:3.0.6 $ docker service create \
--name redis_2 \
--mode global \
redis:3.0.6
``` ```
### Specify service constraints ### Specify service constraints (--constraint)
You can limit the set of nodes where a task can be scheduled by defining You can limit the set of nodes where a task can be scheduled by defining
constraint expressions. Multiple constraints find nodes that satisfy every constraint expressions. Multiple constraints find nodes that satisfy every
@ -178,45 +181,57 @@ $ docker service create \
redis:3.0.6 redis:3.0.6
``` ```
### Container networking ### Attach a service to an existing network (--network)
The containers provisioned in docker swarm mode can be accessed in service discovery either via a Virtual IP (VIP) and routed through the docker swarm ingress overlay network. Or via a DNS round robbin (DNSRR). This configuration is set using the `--endpoint-mode [vip|dnsrr]` setting. Note that dnsrr is incompatible with `--published` ports.
### Service discovery You can use overlay networks to connect one or more services within the swarm.
Discovering other service from within a container can be ac hived via DNS lookup, but you will get different results depending on whether you want the actual service IPs, or the VIP's. First, create an overlay network on a manager node the docker network create
command:
```bash
$ docker network create --driver overlay my-network
etjpu59cykrptrgw0z0hk5snf
``` ```
~> nslookup service
Address: 10.255.0.7 # this is the VIP on the ingress network After you create an overlay network in swarm mode, all manager nodes have
access to the network.
~> nslookup tasks.service When you create a service and pass the --network flag to attach the service to
the overlay network:
Non-authoritative answer: $ docker service create \
Name: tasks.service --replicas 3 \
Address: 10.255.0.26 # this is the real IP of a service on the ingress network --network my-network \
Name: tasks.service --name my-web \
Address: 10.255.0.27 nginx
Name: tasks.service
Address: 10.255.0.24
~> nslookup tasks.service.your_net 716thylsndqma81j6kkkb5aus
The swarm extends my-network to each node running the service.
Name: tasks.service.your_net Containers on the same network can access each other using
Address: 10.0.0.29 # service 1 IP on your net [service discovery](../../swarm/networking.md#use-swarm-mode-service-discovery).
Name: tasks.service.your_net
Address: 10.0.0.26 # service 2 IP on your net
Name: tasks.service.your_net
Address: 10.0.0.28 # service 3 IP on your net
### Publish service ports externally to the swarm (-p, --publish)
~> nslookup service.your_net You can publish service ports to make them available externally to the swarm
using the `--publish` flag:
Non-authoritative answer: ```bash
Name: service.your_net docker service create --publish <TARGET-PORT>:<SERVICE-PORT> nginx
Address: 10.0.0.25 # VIP on your net
``` ```
For example:
```bash
docker service create --name my_web --replicas 3 --publish 8080:80 nginx
```
When you publish a service port, the swarm routing mesh makes the service
accessible at the target port on every node regardless if there is a task for
the service running on the node. For more information refer to
[Use swarm mode routing mesh](../../swarm/ingress.md).
## Related information ## Related information
* [service inspect](service_inspect.md) * [service inspect](service_inspect.md)