在docker swarm服务中执行命令 [英] execute a command within docker swarm service

问题描述

1. 初始化群模式：

1. Initialize swarm mode:

root@ip-172-31-44-207:/home/ubuntu# docker swarm init --advertise-addr 172.31.44.207

Swarm initialized: current node (4mj61oxcc8ulbwd7zedxnz6ce) is now a manager.

To add a worker to this swarm, run the following command:

加入第二个节点：

Join the second node:

docker swarm join \
--token SWMTKN-1-4xvddif3wf8tpzcg23tem3zlncth8460srbm7qtyx5qk3ton55-6g05kuek1jhs170d8fub83vs5 \
172.31.44.207:2377

要将管理员添加到该群集，请运行 docker swarm join-token manager并按照说明进行操作。

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

# start 2 services
docker service create continuumio/miniconda3 

docker service create --name redis redis:3.0.6


root@ip-172-31-44-207:/home/ubuntu# docker service ls
ID            NAME        REPLICAS  IMAGE                   COMMAND
2yc1xjmita67  miniconda3  0/1       continuumio/miniconda3
c3ptcf2q9zv2  redis       1/1       redis:3.0.6

如上所示，redis是它的副本，而miniconda却不是被复制。

As shown above, redis has it's replica while miniconda does not seem to be replicated.

我通常会登录到miniconda容器以键入以下命令：

I do usually log-in to miniconda container to type these commands:

/opt/conda/bin/conda install jupyter -y --quiet && mkdir /opt/notebooks && /opt/conda/bin/jupyter notebook --notebook-dir=/opt/notebooks --ip='*' --port=8888 --no-browser

问题是 docker exec -it XXX bash 命令不适用于群体模式。

The problem is that docker exec -it XXX bash command does not work with swarm mode.

推荐答案

有一个衬套可用于访问本地主机服务的相应实例：

There is one liner for accessing corresponding instance of the service for localhost:

docker exec -ti stack_myservice.1.$(docker service ps -f 'name=stack_myservice.1' stack_myservice -q --no-trunc | head -n1) /bin/bash

已在PowerShell上进行了测试，但bash应该相同。 oneliner访问第一个实例，但在两个位置中用要访问的实例编号替换 1以获得另一个实例。

It is tested on PowerShell, but bash should be the same. The oneliner accesses the first instance, but replace '1' with the number of the instance you want to access in two places to get other one.

更复杂的示例是分布式案例：

More complex example is for distributed case:

#! /bin/bash

set -e

exec_task=$1
exec_instance=$2

strindex() { 
  x="${1%%$2*}"
  [[ "$x" = "$1" ]] && echo -1 || echo "${#x}"
}

parse_node() {
  read title
  id_start=0
  name_start=`strindex "$title" NAME`
  image_start=`strindex "$title" IMAGE`
  node_start=`strindex "$title" NODE`
  dstate_start=`strindex "$title" DESIRED`
  id_length=name_start
  name_length=`expr $image_start - $name_start`
  node_length=`expr $dstate_start - $node_start`

  read line
  id=${line:$id_start:$id_length}
  name=${line:$name_start:$name_length}
  name=$(echo $name)
  node=${line:$node_start:$node_length}
  echo $name.$id
  echo $node
}

if true; then 
   read fn 
   docker_fullname=$fn
   read nn
   docker_node=$nn 
fi < <( docker service ps -f name=$exec_task.$exec_instance --no-trunc -f desired-state=running $exec_task | parse_node )

echo "Executing in $docker_node $docker_fullname" 

eval `docker-machine env $docker_node`

docker exec -ti $docker_fullname /bin/bash

此脚本以后可以用作：

swarm_bash stack_task 1

它只是在所需节点上执行bash。

It just execute bash on required node.

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