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fix swarm service constraint examples 

1. Be more specific about what happens when constraints aren't satified.
    2. There is no `--global`.  Also addressed in network/overlay.md.
    3. Label constraints do not match node labels without `node.label` prefix.

AFAIK neither 2 nor 3 have ever been correct

testedon: 17.06.2-ee-16
This commit is contained in:
Trapier Marshall 2018-09-06 12:36:40 -04:00
parent f20d5af2c7
commit 64279e87a6
2 changed files with 15 additions and 15 deletions
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24
engine/swarm/services.md
View File

@ -621,20 +621,20 @@ labels to ensure that your service is deployed to the appropriate swarm nodes.
Use placement constraints to control the nodes a service can be assigned to. In
the following example, the service only runs on nodes with the
[label](engine/swarm/manage-nodes.md#add-or-remove-label-metadata)
`region` set to `east`. If no appropriately-labelled nodes are available,
deployment fails. The `--constraint` flag uses an equality operator
(`==` or `!=`). For replicated services, it is possible that all services
run on the same node, or each node only runs one replica, or that some nodes
don't run any replicas. For global services, the service runs on every node
that meets the placement constraint and any
[resource requirements](#reserve-cpu-or-memory-for-a-service).
[label](engine/swarm/manage-nodes.md#add-or-remove-label-metadata) `region` set
to `east`. If no appropriately-labelled nodes are available, tasks will wait in
`Pending` until they become available. The `--constraint` flag uses an equality
operator (`==` or `!=`). For replicated services, it is possible that all
services run on the same node, or each node only runs one replica, or that some
nodes don't run any replicas. For global services, the service runs on every
node that meets the placement constraint and any [resource
requirements](#reserve-cpu-or-memory-for-a-service).
```bash
$ docker service create \
--name my-nginx \
--replicas 5 \
--constraint region==east \
--constraint node.labels.region==east \
nginx
```
@ -648,9 +648,9 @@ all nodes where `region` is set to `east` and `type` is not set to `devel`:
```bash
$ docker service create \
--name my-nginx \
--global \
--constraint region==east \
--constraint type!=devel \
--mode global \
--constraint node.labels.region==east \
--constraint node.labels.type!=devel \
nginx
```

6
network/overlay.md
View File

@ -241,9 +241,9 @@ When you connect to a published port on any swarm node (whether it is running a
given service or not), you are redirected to a worker which is running that
service, transparently. Effectively, Docker acts as a load balancer for your
swarm services. Services using the routing mesh are running in _virtual IP (VIP)
mode_. Even a service running on each node (by means of the `--global` flag)
uses the routing mesh. When using the routing mesh, there is no guarantee about
which Docker node services client requests.
mode_. Even a service running on each node (by means of the `--mode global`
flag) uses the routing mesh. When using the routing mesh, there is no guarantee
about which Docker node services client requests.
To bypass the routing mesh, you can start a service using _DNS Round Robin
(DNSRR) mode_, by setting the `--endpoint-mode` flag to `dnsrr`. You must run