问题

I've been trying to deploy my docker consisted of Django, Postgresql and Nginx. It works fine when I do

sudo docker-compose up

However when deploy it on AWS EB, it gives me

could not translate host name "db" to address: Name or service not known

What I've done is I pushed my docker to docker hub using

sudo docker build -t myname/dockername -f Dockerfile .

and I simply do

eb deploy

File Structure

myproject
    myproject
        settings.py
        urls.py
        ...
    Dockerfile
    Dockerrun.aws.json
    manage.py
    requirements.txt
    ...

Dockerfile

FROM python:3
ENV PYTHONUNBUFFERED 1
RUN mkdir /code
WORKDIR /code
COPY requirements.txt /code/
RUN pip install -r requirements.txt
COPY . /code/
EXPOSE 8000
CMD ["sh", "on-container-start.sh"]

Dockerrun.aws.json

{
 "AWSEBDockerrunVersion": "1",
 "Image": {
   "Name": "myname/dockername:latest",
   "Update": "true"
 },
 "Ports": [
   {
     "ContainerPort": "8000"
   }
 ]
}

docker-compose.yml

version: '3'

services:
  db:
    image: postgres
    hostname: db
    networks:
     - some_network
  web:
    restart: always
    build: .
    volumes:
      - .:/code
    hostname: web
    expose:
      - "8000"
    depends_on:
      - db
    links:
      - db:db
    networks:
      - some_network
  nginx:
    image: nginx
    hostname: nginx
    ports:
      - "8000:8000"
    volumes:
      - ./config/nginx:/etc/nginx/conf.d
    depends_on:
      - web
    networks:
      - some_network
networks:
  some_network:

One thing I realize is that when I use docker-compose up on my machine, I get 3 different containers running. However on EB, I see only one container running.

I think it's because I'm fetching the image from docker hub that I built with those files and that somehow caused these 3 containers to be one and it's messing up with recognizing host names? I am quite not sure still. Help will be greatly appreciated. Thanks!

回答1:

`Dockerrun.aws.json` should correlate with `docker-compose.yml`

The reason of issue that host name ”db“ could not be translated to address is that the docker-compose.yml and Dockerrun.aws.json files describe a different architecture:

There are 3 containers in docker-compose.yml
There is only 1 container in Dockerrun.aws.json

Therefore, the application tries to resolve the db hostname and cannot find it, because db not declared in Dockerrun.aws.json

Fix `Dockerrun.aws.json`

So, update your Dockerrun.aws.json. You can do it either manually or using convenient tool micahhausler/container-transform:

a) update it manually

You can use samples, such as:

k2works/aws-eb-docker-multi-container-sample**

b) update it using `micahhausler/container-transform`

You can try micahhausler/container-transform:

Transforms docker-compose, ECS, and Marathon configurations Transforms docker-compose, ECS, and Marathon configurations

Here is what it outputs for your case:

$ container-transform docker-compose.yml > Dockerrun.aws.json

Dockerrun.aws.json

{
    "containerDefinitions": [
        {
            "essential": true,
            "image": "postgres",
            "name": "db"
        },
        {
            "essential": true,
            "image": "nginx",
            "mountPoints": [
                {
                    "containerPath": "/etc/nginx/conf.d",
                    "sourceVolume": "_ConfigNginx"
                }
            ],
            "name": "nginx",
            "portMappings": [
                {
                    "containerPort": 8000,
                    "hostPort": 8000
                }
            ]
        },
        {
            "essential": true,
            "links": [
                "db:db"
            ],
            "mountPoints": [
                {
                    "containerPath": "/code",
                    "sourceVolume": "_"
                }
            ],
            "name": "web"
        }
    ],
    "family": "",
    "volumes": [
        {
            "host": {
                "sourcePath": "."
            },
            "name": "_"
        },
        {
            "host": {
                "sourcePath": "./config/nginx"
            },
            "name": "_ConfigNginx"
        }
    ]
}

Note:: Of course, you should fix missing settings such as memory for db and nginx containers.

You can omit `networks` at all

According to Networking in Compose | Docker Documentation:

For example, suppose your app is in a directory called myapp, and your docker-compose.yml looks like this:

docker-compose.yml

version: "3"
services:
  web:
    build: .
    ports:
      - "8000:8000"
  db:
    image: postgres
    ports:
      - "8001:5432"

When you run docker-compose up, the following happens:

A network called myapp_default is created.

A container is created using web’s configuration. It joins the network myapp_default under the name web.

A container is created using db’s configuration. It joins the network myapp_default under the name db.

So, since all your containers linked to the same some_network, you can omit it.

docker-compose.yml

version: '3'

services:
  db:
    image: postgres
    hostname: db
  web:
    restart: always
    build: .
    volumes:
      - .:/code
    hostname: web
    expose:
      - "8000"
    depends_on:
      - db
    links:
      - db:db
  nginx:
    image: nginx
    hostname: nginx
    ports:
      - "8000:8000"
    volumes:
      - ./config/nginx:/etc/nginx/conf.d
    depends_on:
      - web

And $ container-transform docker-compose.yml > Dockerrun.aws.json will produce:

Dockerrun.aws.json

{
    "containerDefinitions": [
        {
            "essential": true,
            "image": "postgres",
            "name": "db"
        },
        {
            "essential": true,
            "image": "nginx",
            "mountPoints": [
                {
                    "containerPath": "/etc/nginx/conf.d",
                    "sourceVolume": "_ConfigNginx"
                }
            ],
            "name": "nginx",
            "portMappings": [
                {
                    "containerPort": 8000,
                    "hostPort": 8000
                }
            ]
        },
        {
            "essential": true,
            "links": [
                "db:db"
            ],
            "mountPoints": [
                {
                    "containerPath": "/code",
                    "sourceVolume": "_"
                }
            ],
            "name": "web"
        }
    ],
    "family": "",
    "volumes": [
        {
            "host": {
                "sourcePath": "."
            },
            "name": "_"
        },
        {
            "host": {
                "sourcePath": "./config/nginx"
            },
            "name": "_ConfigNginx"
        }
    ]
}

来源：https://stackoverflow.com/questions/57684920/aws-elastic-beanstalk-gives-could-not-translate-host-name-db-to-address-erro

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django