add constraint to service create ref
Signed-off-by: Charles Smith <charles.smith@docker.com>
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@ -94,7 +94,7 @@ ID NAME REPLICAS IMAGE COMMAND
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```
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### Create a service with a rolling update constraints
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### Create a service with a rolling update policy
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```bash
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@ -133,7 +133,7 @@ $ docker service create \
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For more information about labels, refer to [apply custom
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metadata](../../userguide/labels-custom-metadata.md)
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### Service mode
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### Set service mode
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Is this a replicated service or a global service. A replicated service runs as
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many tasks as specified, while a global service runs on each active node in the
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@ -145,6 +145,33 @@ The following command creates a "global" service:
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$ docker service create --name redis_2 --mode global redis:3.0.6
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```
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### Specify service constraints
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You can limit the set of nodes where a task can be scheduled by defining
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constraint expressions. Multiple constraints find nodes that satisfy every
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expression (AND match). Constraints can match node or Docker Engine labels as
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follows:
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| node attribute | matches | example |
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|:------------- |:-------------| :---------------------------------------------|
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| node.id | node ID | `node.id == 2ivku8v2gvtg4` |
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| node.hostname | node hostname | `node.hostname != node-2` |
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| node.role | node role: manager | `node.role == manager` |
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| node.labels | user defined node labels | `node.labels.security == high` |
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| engine.labels | Docker Engine's labels | `engine.labels.operatingsystem == ubuntu 14.04`|
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`engine.labels` apply to Docker Engine labels like operating system,
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drivers, etc. Swarm administrators add `node.labels` for operational purposes by
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using the `docker node update` command.
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For example, the following limits tasks for the redis service to nodes where the
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node type label equals queue:
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```bash
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$ docker service create \
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--name redis_2 \
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--constraint node.labels.type == queue
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```
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## Related information
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