无法链接到由 docker-compose 启动的正在运行的容器

我正在使用 docker 容器设置我的本地开发环境

version: '2'


services:
db:
image: mongo:3
mq:
image: rabbitmq:3
api:
build: .
image: my_app/api
ports:
- "3000:3000"
links:
- db
- mq
environment:
- NODE_ENV=development

一开始就没有错误。 码头工人列出了3个运行中的集装箱

docker-compose up -d
docker ps


e90e5a8b5d33        my_app/api    "/usr/local/bin/node "   0.0.0.0:3000->3000/tcp               my_app_api_1
42bfcd971b16        mongo:3       "/entrypoint.sh mongo"   27017/tcp                            my_app_db_1
a0685a816c47        rabbitmq:3    "/docker-entrypoint.s"   4369/tcp, 5671-5672/tcp, 25672/tcp   my_app_mq_1

但是，当我尝试从另一个容器链接到那些正在运行的容器时

docker run --link my_app_mq_1:mq --link my_app_db_1:db -it worker

我出错了

 docker: Error response from daemon: Cannot link to /my_app_mq_1, as it does not belong to the default network.

我也试过

 docker run --link my_app_mq_1:mq --link my_app_db_1:db -it --net default worker

同样的错误。

那么，我如何链接到一个运行的容器启动的 docker-compose？

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最佳答案

Ok, found the answer to it. In case anyone else comes across the same problem, just do 

docker network ls

This command lists all the docker networks. docker-compose will create a new network when you run docker-compose up. In my case, the network is named as myapp_default.

Note: Your app’s network is given a name based on the “project name”, which is based on the name of the directory it lives in. You can override the project name with either the --project-name flag or the COMPOSE_PROJECT_NAME environment variable. Networking in Compose

So the correct way to link to those containers is

docker run --link my_app_mq_1:mq --link my_app_db_1:db -it --net myapp_default worker
小开

When you use service definition version 2 and more, docker-compose creates user-defined network. Name resolution in a user-defined network works via Docker embedded DNS server. Here's related quote from documentation:

The Docker embedded DNS server enables name resolution for containers connected to a given [user-defined] network. This means that any connected container can ping another container on the same network by its container name.

Containers are also available by network aliases that docker-compose creates. It can be verified by command like:

docker inspect \
-f '\{\{json .NetworkSettings.Networks.myapp_default.Aliases}}' my_app_db_1

It prints ["db","$CONTAINER_ID"].

Providing links with --link will not have any effect in case of existing user-defined network. You can make sure and look at /etc/hosts, which will not have the corresponding lines.

Thus the following command is sufficient:

docker run -it --net myapp_default worker
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my command to run links

docker run --network=YOUR_NETWORK --link SERVICE -t -i app command

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