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Aaron Lehmann a0ccd0d42f Split advertised address from listen address

There are currently problems with "swarm init" and "swarm join" when an
explicit --listen-addr flag is not provided. swarmkit defaults to
finding the IP address associated with the default route, and in cloud
setups this is often the wrong choice.

Introduce a notion of "advertised address", with the client flag
--advertise-addr, and the daemon flag --swarm-default-advertise-addr to
provide a default. The default listening address is now 0.0.0.0, but a
valid advertised address must be detected or specified.

If no explicit advertised address is specified, error out if there is
more than one usable candidate IP address on the system. This requires a
user to explicitly choose instead of letting swarmkit make the wrong
choice. For the purposes of this autodetection, we ignore certain
interfaces that are unlikely to be relevant (currently docker*).

The user is also required to choose a listen address on swarm init if
they specify an explicit advertise address that is a hostname or an IP
address that's not local to the system. This is a requirement for
overlay networking.

Also support specifying interface names to --listen-addr,
--advertise-addr, and the daemon flag --swarm-default-advertise-addr.
This will fail if the interface has multiple IP addresses (unless it has
a single IPv4 address and a single IPv6 address - then we resolve the
tie in favor of IPv4).

This change also exposes the node's externally-reachable address in
docker info, as requested by #24017.

Make corresponding API and CLI docs changes.

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>

2016-07-24 09:23:07 -07:00

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Create a swarm

After you complete the tutorial setup steps, you're ready to create a swarm. Make sure the Docker Engine daemon is started on the host machines.

Open a terminal and ssh into the machine where you want to run your manager node. For example, the tutorial uses a machine named manager1.

Run the following command to create a new swarm:

docker swarm init --advertise-addr <MANAGER-IP>

In the tutorial, the following command creates a swarm on the manager1 machine:

$ docker swarm init --advertise-addr 192.168.99.100
Swarm initialized: current node (dxn1zf6l61qsb1josjja83ngz) is now a manager.

To add a worker to this swarm, run the following command:
    docker swarm join \
    --token SWMTKN-1-49nj1cmql0jkz5s954yi3oex3nedyz0fb0xx14ie39trti4wxv-8vxv8rssmk743ojnwacrr2e7c \
    192.168.99.100:2377

To add a manager to this swarm, run the following command:
    docker swarm join \
    --token SWMTKN-1-61ztec5kyafptydic6jfc1i33t37flcl4nuipzcusor96k7kby-5vy9t8u35tuqm7vh67lrz9xp6 \
    192.168.99.100:2377

The --advertise-addr flag configures the manager node to publish its address as 192.168.99.100. The other nodes in the swarm must be able to access the manager at the IP address.

The output incudes the commands to join new nodes to the swarm. Nodes will join as managers or workers depending on the value for the --swarm-token flag.

Run docker info to view the current state of the swarm:

$ docker info

Containers: 2
Running: 0
Paused: 0
Stopped: 2
  ...snip...
Swarm: active
  NodeID: dxn1zf6l61qsb1josjja83ngz
  Is Manager: true
  Managers: 1
  Nodes: 1
  ...snip...

Run the docker node ls command to view information about nodes:
```
$ docker node ls

ID                           HOSTNAME  STATUS  AVAILABILITY  MANAGER STATUS
dxn1zf6l61qsb1josjja83ngz *  manager1  Ready   Active        Leader
```
The * next to the node id indicates that you're currently connected on this node.

Docker Engine swarm mode automatically names the node for the machine host name. The tutorial covers other columns in later steps.

What's next?

In the next section of the tutorial, we'll add two more nodes to the cluster.

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Create a swarm

What's next?

2.6 KiB

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