docker-compose: multiple images per service

Question

I am trying to create two dockers: one nginx and the other nodejs. However, I find two sets of images are being created. I have deleted all existing images and rebooted the system, yet it shows as below. The relevant files are below.

The following is the docker-compose.yml

services:

  nginx:
    build: ./nginx
    restart: always
    ports:
      - "80:80"
    links:
      - node:node

  node:
    build: ./node
    restart: always
    ports:
      - "8080:8080"
    volumes:
      - ./node:/usr/src/app
      - /usr/src/app/node_modules

The nginx Dockerfile is as follows:

FROM nginx
COPY nginx.conf /etc/nginx/conf.d/default.conf

And the NodeJS Dockerfile as follows:

FROM node:9.3.0-alpine
WORKDIR /usr/src/app
COPY package.json /usr/src/app/

RUN npm install
COPY . /usr/src/app

EXPOSE 8080
CMD [ "npm", "start" ]

The docker images command shows:

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
hudddle_nginx       latest              f784ac4611f5        5 minutes ago       108MB
hudddle_node        latest              5e083ec259e7        5 minutes ago       70.4MB
node                9.3.0-alpine        466bcf8bf36e        3 days ago          67.6MB
nginx               latest              f895b3fb9e30        5 days ago          108MB

Why is it so? The Server (AWS) was created today. Thanks

Answer 1

Thats the correct behaviour

As you using FROM nginx and FROM node in dockerfile, while building docker gets nginz and node images from dockerhub.

So when you want to build docker again , this time it will not download from dockerhub instead it uses local cached image.

Maybe you using below commands to build

docker build -t hudddle_nginx .
docker build -t hudddle_node .

Because of that its base images first nginx and node and then your custom images hudddle_nginx,hudddle_node