8天入門docker系列 —— 第七天 讓你的container實現跨主機訪問

       

         當你有若干個容器以後，你可能就但願實現容器的跨機部署訪問了，好比aspnetcore在一臺host上，mysql在另一個host上，若是要實現這樣的功能，須要你

藉助docker自帶的overlay網絡模型了。

 

一： overlay網絡模型

        要想快速的搭建overlay網絡，你能夠經過docker默認的swarm集羣給你默認生成的名ingress的overlay網絡，這樣會默認開放一些端口供底層機器內的訪問,好比：

UDP 4789 是用於overlay network 流量傳輸的，做爲開發角度，你只須要知道這是一個基於底層物理網絡構建出的一個上層虛擬網絡，而你的程序都是跑在這個虛擬網

絡上，若是要畫圖，大概就是這樣吧！

 

二：經過docker swarm構建overlay網絡

      爲了構建overlay網絡，須要備有兩臺機器（使用虛擬機便可）：

192.168.23.146  manager
192.168.23.147  worker

 

     使用起來很簡單，在 146機器上執行 docker swarm init 初始化一個集羣，同時默認了該機做爲 cluster 的manager節點。

[root@manager ~]# docker swarm init
Swarm initialized: current node (g0o8vkgzruv63hsx4pkjs0yfk) is now a manager.

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

    docker swarm join --token SWMTKN-1-0oxo6qrxwvl8xlneq0jqz2zd87nkj7c0vyf1h9m8kcj3qbzd4v-3eu9zb5athq0s2n79rncbejb1 192.168.23.146:2377

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

[root@manager ~]# docker node ls
ID                            HOSTNAME            STATUS              AVAILABILITY        MANAGER STATUS      ENGINE VERSION
g0o8vkgzruv63hsx4pkjs0yfk *   manager             Ready               Active              Leader              18.09.6
[root@manager ~]# 

   

       當執行完init以後，經過node ls 能夠看到，當前cluster集羣中只有一個node節點，並且仍是Leader，同時docker還告訴咱們怎麼將其餘node加入到集羣中做爲

worker節點，驗證方式是token，好了，那我能夠將這段output copy到 147 的 shell上。

[root@worker ~]#  docker swarm join --token SWMTKN-1-0oxo6qrxwvl8xlneq0jqz2zd87nkj7c0vyf1h9m8kcj3qbzd4v-3eu9zb5athq0s2n79rncbejb1 192.168.23.146:2377
This node joined a swarm as a worker.

 

      最後經過在 146 上執行 docker node ls 看一下集羣信息，能夠看到146，147都在一個集羣了。

[root@manager ~]# docker node ls
ID                            HOSTNAME            STATUS              AVAILABILITY        MANAGER STATUS      ENGINE VERSION
g0o8vkgzruv63hsx4pkjs0yfk *   manager             Ready               Active              Leader              18.09.6
ojjngean30orjzswh72o25rsr     worker              Ready               Active                                  18.09.6

     

     接下來再看一下，4789端口是否開放了，同時看一下ingress的overlay是否開啓了，以下：

[root@manager ~]# docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
f5fbe8d71b5a        bridge              bridge              local
91cfc77a3c7f        docker_gwbridge     bridge              local
ac4a48a43517        host                host                local
5eux1lz4yom7 ingress overlay swarm
02f9bfe179ca        none                null                local
[root@manager ~]# netstat -tlnpu
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      4854/sshd           
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      5523/master         
tcp6       0      0 :::2377                 :::*                    LISTEN      6349/dockerd        
tcp6       0      0 :::7946                 :::*                    LISTEN      6349/dockerd        
tcp6       0      0 :::22                   :::*                    LISTEN      4854/sshd           
tcp6       0      0 ::1:25                  :::*                    LISTEN      5523/master         
udp        0      0 0.0.0.0:47160           0.0.0.0:*                           4549/avahi-daemon:  
udp        0      0 0.0.0.0:68              0.0.0.0:*                           4649/dhclient       
udp        0      0 0.0.0.0:123             0.0.0.0:*                           4555/chronyd        
udp        0      0 127.0.0.1:323           0.0.0.0:*                           4555/chronyd        
udp 0      0 0.0.0.0:4789            0.0.0.0:*                           -                   
udp        0      0 0.0.0.0:5353            0.0.0.0:*                           4549/avahi-daemon:  
udp        0      0 0.0.0.0:26134           0.0.0.0:*                           4649/dhclient       
udp6       0      0 :::123                  :::*                                4555/chronyd        
udp6       0      0 ::1:323                 :::*                                4555/chronyd        
udp6       0      0 :::47743                :::*                                4649/dhclient       
udp6       0      0 :::7946                 :::*                                6349/dockerd  

  

     默認名爲ingress 的overlay driver是默認是不支持standalone容器加入的，因此我須要從新new一個overlay，並設置一下容許standalone容器加入此網絡，好了，

說幹就幹，new了一個 test-net的overlay網絡，經過--attachable 開啓附加功能。

[root@manager ~]# docker network create --driver=overlay --attachable test-net
dajh2glpfattdnq2ahqchlhur
[root@manager ~]# docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
f5fbe8d71b5a        bridge              bridge              local
91cfc77a3c7f        docker_gwbridge     bridge              local
ac4a48a43517        host                host                local
5eux1lz4yom7        ingress             overlay             swarm
02f9bfe179ca        none                null                local
dajh2glpfatt test-net            overlay             swarm

 

三：python 跨機鏈接 redis

     我準備把redis放在147機器上， python application 放在 146上，python 經過 對方的容器名（some-redis） 進行鏈接，以下圖所示：

 

 

1. 在147上執行docker run時附加 network 爲指定的 test-net 網絡

[root@worker ~]# docker run --network test-net --name some-redis -d redis
eca08e67e35160661e090ca42a61dacaee5dd8ca99f8e9c25e59ae6927d66328

 

2. python應用程序

主要有三個部分，app.py, Dockerfile, requirements.txt。

《1》 app.py

      下面要注意的是，在redis的構造函數中指定了host= some-redis ，也就是 147啓動容器名。

from flask import Flask
from redis import Redis, RedisError
import os
import socket

# Connect to Redis
redis = Redis(host="some-redis", db=0, socket_connect_timeout=2, socket_timeout=2)

app = Flask(__name__)

@app.route("/")
def hello():
    try:
        visits = redis.incr("counter")
    except RedisError:
        visits = "<i>cannot connect to Redis, counter disabled</i>"

    html = "<b>Hostname:</b> {hostname}<br/>" \
           "<b>Visits:</b> {visits}"
    return html.format(hostname=socket.gethostname(), visits=visits)

if __name__ == "__main__":
    app.run(host='0.0.0.0', port=80)

 

《2》 Flask 和 Redis 依賴包 （requirements.txt）

Flask
Redis

 

《3》 最後就是dockerfile

FROM python:2.7-slim

WORKDIR /app

COPY . .

EXPOSE 80

RUN pip install --trusted-host pypi.python.org -r requirements.txt

VOLUME [ "/app" ]

CMD [ "python", "app.py" ]

 

有了這三個，接下來就能夠構建image了。

[root@manager app]# docker build -t pyweb:v1 .
Sending build context to Docker daemon  4.608kB
Step 1/7 : FROM python:2.7-slim
2.7-slim: Pulling from library/python
fc7181108d40: Already exists 
8c60b810a35a: Pull complete 
d207b275197c: Pull complete 
63184f224d60: Pull complete 
Digest: sha256:1405fa2f8e9a232e2f60cafbb2b06ca2f1e0f577f4b4c397c361d6dba59fd24e
Status: Downloaded newer image for python:2.7-slim
 ---> ca96bab3e2aa
Step 2/7 : WORKDIR /app
 ---> Running in 6b8324c10dc0
Removing intermediate container 6b8324c10dc0
 ---> a85fb403c57b
Step 3/7 : COPY . .
 ---> f13015df5bf7
Step 4/7 : EXPOSE 80
 ---> Running in 408a718df2b4
Removing intermediate container 408a718df2b4
 ---> 39d30c3a092d
Step 5/7 : RUN pip install --trusted-host pypi.python.org -r requirements.txt
 ---> Running in 0ee0982739d5
DEPRECATION: Python 2.7 will reach the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 won't be maintained after that date. A future version of pip will drop support for Python 2.7.
Collecting Flask (from -r requirements.txt (line 1))
  Downloading https://files.pythonhosted.org/packages/c3/31/6904ac846fc65a7fa6cac8b4ddc392ce96ca08ee67b0f97854e9575bbb26/Flask-1.1.0-py2.py3-none-any.whl (94kB)
Collecting Redis (from -r requirements.txt (line 2))
  Downloading https://files.pythonhosted.org/packages/ac/a7/cff10cc5f1180834a3ed564d148fb4329c989cbb1f2e196fc9a10fa07072/redis-3.2.1-py2.py3-none-any.whl (65kB)
Collecting Jinja2>=2.10.1 (from Flask->-r requirements.txt (line 1))
  Downloading https://files.pythonhosted.org/packages/1d/e7/fd8b501e7a6dfe492a433deb7b9d833d39ca74916fa8bc63dd1a4947a671/Jinja2-2.10.1-py2.py3-none-any.whl (124kB)
Collecting click>=5.1 (from Flask->-r requirements.txt (line 1))
  Downloading https://files.pythonhosted.org/packages/fa/37/45185cb5abbc30d7257104c434fe0b07e5a195a6847506c074527aa599ec/Click-7.0-py2.py3-none-any.whl (81kB)
Collecting Werkzeug>=0.15 (from Flask->-r requirements.txt (line 1))
  Downloading https://files.pythonhosted.org/packages/9f/57/92a497e38161ce40606c27a86759c6b92dd34fcdb33f64171ec559257c02/Werkzeug-0.15.4-py2.py3-none-any.whl (327kB)
Collecting itsdangerous>=0.24 (from Flask->-r requirements.txt (line 1))
  Downloading https://files.pythonhosted.org/packages/76/ae/44b03b253d6fade317f32c24d100b3b35c2239807046a4c953c7b89fa49e/itsdangerous-1.1.0-py2.py3-none-any.whl
Collecting MarkupSafe>=0.23 (from Jinja2>=2.10.1->Flask->-r requirements.txt (line 1))
  Downloading https://files.pythonhosted.org/packages/fb/40/f3adb7cf24a8012813c5edb20329eb22d5d8e2a0ecf73d21d6b85865da11/MarkupSafe-1.1.1-cp27-cp27mu-manylinux1_x86_64.whl
Installing collected packages: MarkupSafe, Jinja2, click, Werkzeug, itsdangerous, Flask, Redis
Successfully installed Flask-1.1.0 Jinja2-2.10.1 MarkupSafe-1.1.1 Redis-3.2.1 Werkzeug-0.15.4 click-7.0 itsdangerous-1.1.0
Removing intermediate container 0ee0982739d5
 ---> 704e7d655494
Step 6/7 : VOLUME [ "/app" ]
 ---> Running in 0c4ad68db249
Removing intermediate container 0c4ad68db249
 ---> 5b0ce6eef187
Step 7/7 : CMD [ "python", "app.py" ]
 ---> Running in 388d972cbd6d
Removing intermediate container 388d972cbd6d
 ---> fd7a0ffca7fc
Successfully built fd7a0ffca7fc
Successfully tagged pyweb:v1
[root@manager app]# docker run -d --network test-net -p 80:80 -v /app:/app --name pyapp pyweb:v1
9d419507b00adddd003f8e45580ec1ee48d4a0347091b65da1bc183a8bbe1dc2
[root@manager app]# docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS                NAMES
9d419507b00a        pyweb:v1            "python app.py"     4 seconds ago       Up 2 seconds        0.0.0.0:80->80/tcp   pyapp
[root@manager app]# 

 

     而後訪問一下  http://192.168.23.146，每刷新一下page，都會執行一次redis.incr操做。，這樣就實現了多容器之間的跨機器訪問，你們也能夠把這些放到

docker-compose文件中哦。

 

 

 好了，本篇就說到這裏，但願對你有幫助。