Docker swarm mode and dockerswarm Mode

Docker swarm mode and dockerswarm Mode

Docker 1.12 and later versions integrate swarmkit and other orchestration services. The current docker version is 1.12-rc2. This article will try to use this mode to create a native docker Cluster

This article includes the following points:

Initialize a docker engine cluster in swarm Mode

Add node to swarm

Publish an application service to swarm

Perform swarm management after running

Set

The following requirements are required to try this example:

Three interconnected hosts:

Install docker 1.12 or later

IP address of the Management Node

Enable ports between hosts

TCP port 2377 Cluster Management Port

Communication Port Between TCP and UDP port 7946 nodes

TCP and UDP port 4789 overlay Network Communication Port

Iptables-a input-p tcp -- dport 2377-j ACCEPT

Iptables-a input-p tcp -- dport 7946-j ACCEPT

Iptables-a input-p udp -- dport 7946-j ACCEPT

Iptables-a input-p tcp -- dport 4789-j ACCEPT

Iptables-a input-p udp -- dport 4789-j ACCEPT

Create a swarm Cluster

Create a management Node

Docker swarm init -- listen-addr: 1

As follows:

[Root @ centos01 container] # docker swarm init -- listen-addr 172.18.18.201: 2377

Swarm initialized: current node (4am2qb52uw8r2ubxlkq3bxzyl) is now a manager.

[Root @ centos01 container] # docker info

Containers: 11

Running: 7

Paused: 0

Stopped: 4

Images: 5

Server Version: 1.12.0-rc1

Storage Driver: devicemapper

Pool Name: docker-253: 0-2098542-pool

Pool Blocksize: 65.54 kB

Base Device Size: 10.74 GB

Backing Filesystem: xfs

Data file:/dev/loop0

Metadata file:/dev/loop1

Data Space Used: 1.251 GB

Data Space Total: 107.4 GB

Data Space Available: 36.45 GB

Metadata Space Used: 2.642 MB

Metadata Space Total: 2.147 GB

Metadata Space Available: 2.145 GB

Thin Pool Minimum Free Space: 10.74 GB

Udev Sync Supported: true

Deferred Removal Enabled: false

Deferred Deletion Enabled: false

Deferred Deleted Device Count: 0

Data loop file:/var/lib/docker/devicemapper/data

WARNING: Usage of loopback devices is stronugly discouraged for production use. either use '-- storage-opt dm. thinpooldev 'or use' -- storage-opt dm. no_warn_on_loop_devices = true 'to suppress this warning.

Metadata loop file:/var/lib/docker/devicemapper/metadata

Library Version: 1.02.107-RHEL7 (2015-12-01)

Logging Driver: json-file

Cgroup Driver: cgroupfs

Plugins:

Volume: local

Network: null bridge host overlay

Swarm: active

NodeID: 4am2qb52uw8r2ubxlkq3bxzyl

IsManager: Yes

Managers: 1

Nodes: 1

CACertHash: sha256: ipv6ba735e22975ecba482e122e881fc1cac28ed43443e0bf1a4127f354f2cb3

Runtimes: default

Default Runtime: default

Kernel Version: 4.6.2-1. el7.elrepo. x86_64

Operating System: CentOS Linux 7 (Core)

OSType: linux

Architecture: x86_64

CPUs: 2

Total Memory: 992 MiB

Name: centos01

ID: 5OPS: GL5A: IKVO: 74U5: 3T3T: EBSW: 5REH: USD3: AM3S: DRU4: ZLOW: EEKK

Docker Root Dir:/var/lib/docker

Debug Mode (client): false

Debug Mode (server): false

Registry: https://index.docker.io/v1/

WARNING: bridge-nf-call-ip6tables is disabled

Insecure Registries:

127.0.0.0/8

[Root @ centos01 container] # docker node ls

ID NAME MEMBERSHIP STATUS AVAILABILITY MANAGER STATUS LEADER

4am2qb52uw8r2ubxlkq3bxzyl * centos01 Accepted Ready Active Reachable Yes

Add a node to a cluster

Run the following command on the node Machine

Docker swarm join: 1

For example:

Docker swarm join 172.18.18.201: 2377

This node joined a Swarm as a worker.

View nodes on the manager node

[Vagrant @ centos01 ~] $ Docker node ls

ID NAME MEMBERSHIP STATUS AVAILABILITY MANAGER STATUS LEADER

8i07v3mx5ogdz1z68iide3yrn centos03 Accepted Ready Active

Cioe124z1315ucs5rwd8n2dv * centos01 Accepted Ready Active Reachable Yes

Dfsp35af3tvt1ztf6ffcehtko centos02 Accepted Ready Active

Publish Service

Run the following command on the manager:

[Vagrant @ centos01 ~] $ Docker service create -- replicas 1 -- name helloworld alpine ping docker.com

6gxhvlwx8uqbio7fn2yxnw1yg

Docker service create command to create a service.

-- Name: the service is named helloworld.

-- Replicas label to declare one running entity in detail.

The parameter alpine ping docker.com defines the execution of pingg docker.com as the service of the alpine container.

Use docker service ls to view services

[Vagrant @ centos01 ~] $ Docker service ls

ID NAME SCALE IMAGE COMMAND

6gxhvlwx8uqb helloworld 1 alpine ping docker.com

Use docker service inspect Review service

[Vagrant @ centos01 ~] $ Docker service inspect -- pretty helloworld

ID: 6gxhvlwx8uqbio7fn2yxnw1yg

Name: helloworld

Mode: REPLICATED

Replicas: 1

Placement:

Strategy: SPREAD

UpateConfig:

Parallelism: 1

ContainerSpec:

Image: alpine

Args: ping docker.com

Use docker service tasks to view the node on which the service runs

[Vagrant @ centos01 ~] $ Docker service tasks helloworld

ID NAME SERVICE IMAGE LAST STATE DESIRED STATE NODE

30nkhczhr8g1ot6jh9couixed helloworld.1 helloworld alpine Running 10 minutes Running centos01

[Vagrant @ centos01 ~] $ Docker ps

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES

8b1e88baadfd alpine: latest "ping docker.com" 10 minutes ago Up 10 minutes helloworld.1.30nkhczhr8g1ot6jh9couixed

Scale service

Docker service scale = 1

For example:

[Vagrant @ centos01 ~] $ Docker service scale helloworld = 5

Helloworld scaled to 5

[Vagrant @ centos01 ~] $ Docker service tasks helloworld

ID NAME SERVICE IMAGE LAST STATE DESIRED STATE NODE

30nkhczhr8g1ot6jh9couixed helloworld.1 helloworld alpine Running 13 minutes Running centos01

20172ini5ovypy24umr85grcm6g helloworld.2 helloworld alpine Preparing 19 seconds Running centos03

4trr53ebdpzxo7wnjfet7gpl6 helloworld.3 helloworld alpine Preparing 19 seconds Running centos02

38t0tzje48uk63ros32olrfou helloworld.4 helloworld alpine Preparing 19 seconds Running centos02

Exe4vkbsboy2l2lwylbi9g8o helloworld.5 helloworld alpine Running 19 seconds Running centos01

Delete service

[Vagrant @ centos01 ~] $ Docker service rm helloworld

Helloworld

[Vagrant @ centos01 ~] $ Docker service inspect helloworld

[]

Error: no such service: helloworld

Rolling upgrade

$ Docker service create -- replicas 3 -- name redis -- update-delay 10 s -- update-parallelism 1 redis: 3.0.6

0u6a4s31ybk7yw2wyvtikmu50

[Root @ centos01 docker] # docker service ls

ID NAME SCALE IMAGE COMMAND

3h9kbnrw5lgg redis 3 redis: 3.0.6

[Root @ centos01 docker] # docker service tasks redis

ID NAME SERVICE IMAGE LAST STATE DESIRED STATE NODE

Bstvlwynaw6shfv9rgiinyuvp redis.1 redis: 3.0.6 Running 16 minutes Running centos03

7xnp1n5ii9667xbvr1eaefyqu redis.2 redis: 3.0.6 Running 16 minutes Running centos02

8w3pnr57j0sb8jpieu9wkuudf redis.3 redis: 3.0.6 Running 16 minutes Running centos01

[Vagrant @ centos01 ~] $ Docker service update -- image redis: 3.0.7 redis

Redis

[Root @ centos01 docker] # docker service ls

ID NAME SCALE IMAGE COMMAND

3h9kbnrw5lgg redis 3 redis: 3.0.7

[Root @ centos01 docker] # docker service tasks redis

ID NAME SERVICE IMAGE LAST STATE DESIRED STATE NODE

Bstvlwynaw6shfv9rgiinyuvp redis.1 redis: 3.0.6 Running 17 minutes Running centos03

Bkq2qi6j5uq6tl3jn37nurq0z redis.2 redis: 3.0.7 Preparing 6 seconds Running centos02

8w3pnr57j0sb8jpieu9wkuudf redis.3 redis: 3.0.6 Running 17 minutes Running centos01

[Vagrant @ centos01 ~] $ Docker service inspect -- pretty redis

ID: 3h9kbnrw5lggasae7zl8umw7m

Name: redis

Mode: REPLICATED

Replicas: 3

Placement:

Strategy: SPREAD

UpateConfig:

Parallelism: 1

Delay: 10 s

ContainerSpec:

Image: redis: 3.0.7

-- Update-parallelism label to configure the number of synchronization upgrade tasks in the service.

-- Update-delay label: configure the delay for upgrading a service task or a series of tasks.

Node offline

In some cases, you need to maintain a node. In this case, the node may be disconnected from the network or shut down, making the service available on the node. Use docker node update -- availability drain to deprecate the node. swarm closes the containers on the current node and starts the containers on other nodes. After the maintenance is complete, you need to go online and change the node status to active. The command is as follows: docker node update -- availability active