github.com/brahmaroutu/docker@v1.2.1-0.20160809185609-eb28dde01f16/docs/swarm/swarm-mode.md

github.com/brahmaroutu/docker@v1.2.1-0.20160809185609-eb28dde01f16/docs/swarm/swarm-mode.md (about)

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12
13 # Run Docker Engine in swarm mode
14
15 When you first install and start working with Docker Engine, swarm mode is
16 disabled by default. When you enable swarm mode, you work with the concept of
17 services managed through the `docker service` command.
18
19 There are two ways to run the Engine in swarm mode:
20
21 * Create a new swarm, covered in this article.
22 * [Join an existing swarm](join-nodes.md).
23
24 When you run the Engine in swarm mode on your local machine, you can create and
25 test services based upon images you've created or other available images. In
26 your production environment, swarm mode provides a fault-tolerant platform with
27 cluster management features to keep your services running and available.
28
29 These instructions assume you have installed the Docker Engine 1.12 or later on
30 a machine to serve as a manager node in your swarm.
31
32 If you haven't already, read through the [swarm mode key concepts](key-concepts.md)
33 and try the [swarm mode tutorial](swarm-tutorial/index.md).
34
35 ## Create a swarm
36
37 When you run the command to create a swarm, the Docker Engine starts running in swarm mode.
38
39 Run [`docker swarm init`](../reference/commandline/swarm_init.md)
40 to create a single-node swarm on the current node. The Engine sets up the swarm
41 as follows:
42
43 * switches the current node into swarm mode.
44 * creates a swarm named `default`.
45 * designates the current node as a leader manager node for the swarm.
46 * names the node with the machine hostname.
47 * configures the manager to listen on an active network interface on port 2377.
48 * sets the current node to `Active` availability, meanining it can receive tasks
49 from the scheduler.
50 * starts an internal distributed data store for Engines participating in the
51 swarm to maintain a consistent view of the swarm and all services running on it.
52 * by default, generates a self-signed root CA for the swarm.
53 * by default, generates tokens for worker and manager nodes to join the
54 swarm.
55 * creates an overlay network named `ingress` for publishing service ports
56 external to the swarm.
57
58 The output for `docker swarm init` provides the connection command to use when
59 you join new worker nodes to the swarm:
60
61 ```bash
62 $ docker swarm init
63 Swarm initialized: current node (dxn1zf6l61qsb1josjja83ngz) is now a manager.
64
65 To add a worker to this swarm, run the following command:
66
67 docker swarm join \
68 --token SWMTKN-1-49nj1cmql0jkz5s954yi3oex3nedyz0fb0xx14ie39trti4wxv-8vxv8rssmk743ojnwacrr2e7c \
69 192.168.99.100:2377
70
71 To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
72 ```
73
74 ### Configure the advertise address
75
76 Manager nodes use an advertise address to allow other nodes in the swarm access
77 to the Swarmkit API and overlay networking. The other nodes on the swarm must be
78 able to access the manager node on its advertise address IP address.
79
80 If you don't specify an advertise address, Docker checks if the system has a
81 single IP address. If so, Docker uses the IP address with with the listening
82 port `2377` by default. If the system has multiple IP addresses, you must
83 specify the correct `--advertise-addr` to enable inter-manager communication
84 and overlay networking:
85
86 ```bash
87 $ docker swarm init --advertise-addr <MANAGER-IP>
88 ```
89
90 You must also specify the `--advertise-addr` if the address where other nodes
91 reach the first manager node is not the same address the manager sees as its
92 own. For instance, in a cloud setup that spans different regions, hosts have
93 both internal addresses for access within the region and external addresses that
94 you use for access from outside that region. In this case, specify the external
95 address with `--advertise-addr` so that the node can propogate that information
96 to other nodes that subsequently connect to it.
97
98 Refer to the `docker swarm init` [CLI reference](../reference/commandline/swarm_init.md)
99 for more detail on the advertise address.
100
101 ### View the join command or update a swarm join token
102
103 Nodes require a secret token to join the swarm. The token for worker nodes is
104 different from the token for manager nodes. Nodes only use the join-token at the
105 moment they join the swarm. Rotating the join token after a node has already
106 joined a swarm does not affect the node's swarm membership. Token rotation
107 ensures an old token cannot be used by any new nodes attempting to join the
108 swarm.
109
110 To retrieve the join command including the join token for worker nodes, run:
111
112 ```bash
113 $ docker swarm join-token worker
114
115 To add a worker to this swarm, run the following command:
116
117 docker swarm join \
118 --token SWMTKN-1-49nj1cmql0jkz5s954yi3oex3nedyz0fb0xx14ie39trti4wxv-8vxv8rssmk743ojnwacrr2e7c \
119 192.168.99.100:2377
120
121 This node joined a swarm as a worker.
122 ```
123
124 To view the join command and token for manager nodes, run:
125
126 ```bash
127 $ docker swarm join-token manager
128
129 To add a worker to this swarm, run the following command:
130
131 docker swarm join \
132 --token SWMTKN-1-49nj1cmql0jkz5s954yi3oex3nedyz0fb0xx14ie39trti4wxv-8vxv8rssmk743ojnwacrr2e7c \
133 192.168.99.100:2377
134 ```
135
136 Pass the `--quiet` flag to print only the token:
137
138 ```bash
139 $ docker swarm join-token --quiet worker
140
141 SWMTKN-1-49nj1cmql0jkz5s954yi3oex3nedyz0fb0xx14ie39trti4wxv-8vxv8rssmk743ojnwacrr2e7c
142 ```
143
144 Be careful with the join tokens because they are the secrets necessary to join
145 the swarm. In particular, checking a secret into version control is a bad
146 practice because it would allow anyone with access to the the application source
147 code to add new nodes to the swarm. Manager tokens are especially sensitive
148 because they allow a new manager node to join and gain control over the whole
149 swarm.
150
151 We recommend that you rotate the join tokens in the following circumstances:
152
153 * If a token was checked-in by accident into a version control system, group
154 chat or accidentally printed to your logs.
155 * If you suspect a node has been compromised.
156 * If you wish to guarantee that no new nodes can join the swarm.
157
158 Additionally, it is a best practice to implement a regular rotation schedule for
159 any secret including swarm join tokens. We recommend that you rotate your tokens
160 at least every 6 months.
161
162 Run `swarm join-token --rotate` to invalidate the old token and generate a new
163 token. Specify whether you want to rotate the token for `worker` or `manager`
164 nodes:
165
166 ```bash
167 $docker swarm join-token --rotate worker
168
169 To add a worker to this swarm, run the following command:
170
171 docker swarm join \
172 --token SWMTKN-1-2kscvs0zuymrsc9t0ocyy1rdns9dhaodvpl639j2bqx55uptag-ebmn5u927reawo27s3azntd44 \
173 172.17.0.2:2377
174 ```
175
176 ## Learn More
177
178 * [Join nodes to a swarm](join-nodes.md)
179 * `swarm init`[command line reference](../reference/commandline/swarm_init.md)
180 * [Swarm mode tutorial](swarm-tutorial/index.md)