阿葛廷

人一定要靠自己!

2 minute read

Tags:

  • section3-33, 34

Udemy

Assignment Requirements

  • Know how to use -it to get shell in container
  • Understand basics of what a Linux distribution is like Ubuntu and CentOS
  • know how to run a container
  • Understand basics of DNS records

Assiginment: DNS Round Robin Test

  • Round-robin DNS

  • Ever since Docker Engine 1.11, we can have multiple containers on a created network respond to the same DNS address

  • Create a new virtual network (default bridge driver)

  • Create two containers from elasticsearch:2 image

  • Research and use --network-alias search when createing them to give them an additional DNS name to repond to

  • Run alpine nslookup search with --net to see the two containers list for the same DNS name

  • Run centos curl -s search:9200 wiht --net multiple times until you see both “name” fields show

解

靠! 自己寫都錯 XDD

  • 額外 remove all stop containers

    • docker rm $(docker ps -a -q)

--net-alias and --network-alias both work

  • docker network create dude

  • docker container run -d --net dude --net-alias search elasticesearch:2

  • 看自己的筆記

    • 寫到 Docker defaults the hostname to the container’s name, but you can also set aliases。喔~~~ 更清楚了~ 所以這作業，把兩個 elasticesearch 的 DNS 都叫做 search --net-alias search。
PS E:\> docker network create dude
a666a0d65d142da0ab965b5f47dbbaa6e0373d40c1b72c20a581d3eae6fc5ef1
PS E:\> docker container run -d --net dude --net-alias search elasticsearch:2
740ee010200edac465cde92f59631ce01e8ba3a23c7788e6105dd98f3970bcc3
PS E:\> docker container run -d --net dude --net-alias search elasticsearch:2
b7fee62524a6d14f819c74b41478203cb61a9cf7d7fef839c2979624c3c7d0bc
  • 看看現在 container 的狀態
PS E:\> docker container ls
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                NAMES
b7fee62524a6        elasticsearch:2     "/docker-entrypoint.…"   24 minutes ago      Up 24 minutes       9200/tcp, 9300/tcp   blissful_boyd
740ee010200e        elasticsearch:2     "/docker-entrypoint.…"   24 minutes ago      Up 24 minutes       9200/tcp, 9300/tcp   beautiful_lovelace

開一個 alpine nslookup <dns-name>

        [在docker env 裡面先接到和兩個 elasticsearch containers同一個network]
                                     |
PS E:\> docker container run --rm --net dude alpine nslookup search
nslookup: can't resolve '(null)': Name does not resolve

Name:      search
Address 1: 172.21.0.3 search.dude
Address 2: 172.21.0.2 search.dude

開 Centos curl 抓抓 -s <dns-name>:port 完美實作 RR TEST

  • docker container run --rm --net dude centos curl -s search:9200
PS E:\> docker container run --rm --net dude  centos curl -s search:9200
{
  "name" : "Arranger",
  "cluster_name" : "elasticsearch",
  "cluster_uuid" : "Q6ahATWOTFOgipKV0Js8-g",
  "version" : {
    "number" : "2.4.6",
    "build_hash" : "5376dca9f70f3abef96a77f4bb22720ace8240fd",
    "build_timestamp" : "2017-07-18T12:17:44Z",
    "build_snapshot" : false,
    "lucene_version" : "5.5.4"
  },
  "tagline" : "You Know, for Search"
}
PS E:\> docker container run --rm --net dude  centos curl -s search:9200
{
  "name" : "Sun Girl",
  "cluster_name" : "elasticsearch",
  "cluster_uuid" : "znEKY48aRwKucupK3OiHDw",
  "version" : {
    "number" : "2.4.6",
    "build_hash" : "5376dca9f70f3abef96a77f4bb22720ace8240fd",
    "build_timestamp" : "2017-07-18T12:17:44Z",
    "build_snapshot" : false,
    "lucene_version" : "5.5.4"
  },
  "tagline" : "You Know, for Search"
}

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