使用容器名称从主机访问Docker容器 [英] Access docker container from host using containers name

问题描述

我正在开发服务，并在那里使用docker compose来旋转诸如postgres，redis，elasticsearch之类的服务。我有一个基于RubyOnRails的Web应用程序，并从所有这些服务中读写。

I am developing a service and using there docker compose to spin services like postgres, redis, elasticsearch. I have a web application that is based on RubyOnRails and writes and reads from all those services.

这是我的 docker-compose.yml

version: '2'

services:
  redis:
    image: redis:2.8
    networks:
      - frontapp

  elasticsearch:
    image: elasticsearch:2.2
    networks:
      - frontapp

  postgres:  
    image: postgres:9.5
    environment:
      POSTGRES_USER: elephant
      POSTGRES_PASSWORD: smarty_pants
      POSTGRES_DB: elephant
    volumes:
      - /var/lib/postgresql/data
    networks:
      - frontapp

networks:
  frontapp:
    driver: bridge

我可以在该网络中ping容器

And i can ping containers within this network

$ docker-compose run redis /bin/bash
root@777501e06c03:/data# ping postgres
PING postgres (172.20.0.2): 56 data bytes
64 bytes from 172.20.0.2: icmp_seq=0 ttl=64 time=0.346 ms
64 bytes from 172.20.0.2: icmp_seq=1 ttl=64 time=0.047 ms
...

到目前为止很好。现在，我想在主机上的Rails应用程序上运行ruby，但是能够使用 postgresql：// username：password @ postgres / database 这样的URL访问postgres实例，即

So far so good. Now I want to run ruby on rails application on my host machine but be able to access postgres instance with url like postgresql://username:password@postgres/database currently that is not possible

$ ping postgres
ping: unknown host postgres

我可以在docker中看到我的网络

I can see my network in docker

$ docker network ls
NETWORK ID          NAME                DRIVER
ac394b85ce09        bridge              bridge              
0189d7e86b33        elephant_default    bridge              
7e00c70bde3b        elephant_frontapp   bridge              
a648554a72fa        host                host                
4ad9f0f41b36        none                null 

我可以看到它的界面

$ ifconfig 
br-0189d7e86b33 Link encap:Ethernet  HWaddr 02:42:76:72:bb:c2  
          inet addr:172.18.0.1  Bcast:0.0.0.0  Mask:255.255.0.0
          inet6 addr: fe80::42:76ff:fe72:bbc2/64 Scope:Link
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:36 errors:0 dropped:0 overruns:0 frame:0
          TX packets:60 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:2000 (2.0 KB)  TX bytes:8792 (8.7 KB)

br-7e00c70bde3b Link encap:Ethernet  HWaddr 02:42:e7:d1:fe:29  
          inet addr:172.20.0.1  Bcast:0.0.0.0  Mask:255.255.0.0
          inet6 addr: fe80::42:e7ff:fed1:fe29/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1584 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1597 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:407137 (407.1 KB)  TX bytes:292299 (292.2 KB)
...

但是我不知道下一步该怎么做。我尝试使用 /etc/resolv.conf 玩游戏，主要是使用 nameserver 指令，但是没有效果。

But i am not sure what should I do next. I tried to play a bit with /etc/resolv.conf, mainly with nameserver directive, but that had no effect.

对于建议如何正确配置此设置的建议，我将不胜感激。

I would appreciate any help of suggestions how to configure this setup correctly.

UPDATE

浏览Internet资源后，我设法为框分配了静态IP地址。就目前而言，继续开发就足够了。这是我当前的 docker-compose.yml

After browsing through Internet resources I managed to assign static IP addresses to boxes. For now it is enough for me to continue development. Here is my current docker-compose.yml

version: '2'

services:
  redis:
    image: redis:2.8
    networks:
      frontapp:
        ipv4_address: 172.25.0.11

  elasticsearch:
    image: elasticsearch:2.2
    networks:
      frontapp:
        ipv4_address: 172.25.0.12

  postgres:  
    image: postgres:9.5
    environment:
      POSTGRES_USER: elephant
      POSTGRES_PASSWORD: smarty_pants
      POSTGRES_DB: elephant
    volumes:
      - /var/lib/postgresql/data
    networks:
      frontapp:
        ipv4_address: 172.25.0.10

networks:
  frontapp:
    driver: bridge
    ipam:
      driver: default
      config:
        - subnet: 172.25.0.0/16
          gateway: 172.25.0.1

推荐答案

有一个开源应用程序可以解决此问题问题，它称为 DNS代理服务器，此处是一些示例来自官方存储库

There is a opensource application that solves this issue, it's called DNS Proxy Server, here some examples from official repository

这是一个DNS解决容器主机名的服务器，如果找不到匹配的主机名，也可以从互联网上解决它。

It's a DNS server that solves containers hostnames, if could not found a hostname that matches then solve it from internet as well

$ docker run --hostname dns.mageddo --restart=unless-stopped -p 5380:5380 \
-v /var/run/docker.sock:/var/run/docker.sock \
-v /etc/resolv.conf:/etc/resolv.conf \
defreitas/dns-proxy-server

它将自动设置为默认DNS（并在停止时恢复为原始DNS）

It will be set automatically as your default DNS (and recover to the original when it stops)

检查docker-compose文件

checking docker-compose file

$ cat docker-compose.yml
version: '3'
services:
  nginx-1:
    image: nginx
    hostname: nginx-1.docker
    network_mode: bridge 
  linux-1:
    image: alpine
    hostname: linux-1.docker
    command: sh -c 'apk add --update bind-tools && tail -f /dev/null'
    network_mode: bridge # that way he can solve others containers names even inside, solve nginx-2, for example

启动容器

$ docker-compose up

解决容器

来自主机

nslookup nginx-1.docker
Server:     13.0.0.5
Address:    13.0.0.5#53
Non-authoritative answer:
Name:   nginx-1.docker
Address: 13.0.0.6

来自另一个容器

$ docker-compose exec linux-1 ping nginx-1.docker
PING nginx-1.docker (13.0.0.6): 56 data bytes
64 bytes from 13.0.0.6: seq=0 ttl=64 time=0.034 ms

它还可以解决Internet主机名

$ nslookup google.com
Server:     13.0.0.5
Address:    13.0.0.5#53

Non-authoritative answer:
Name:   google.com
Address: 216.58.202.78

这篇关于使用容器名称从主机访问Docker容器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！