Reusing docker image in docker-compose

Question

I've seen the following in https://www.distributedpython.com/2018/11/15/celery-docker/

Which reuses the built image I believe

services: 
  worker:
    build: .
    image: &img worker 
 
  beat:
    build: .
    image: *img

Since I'm using Dockerfile, I can do something like this, I see it's rebuilding the image (pip install in Dockerfile runs twice for each service)

 services:
   worker:
     build:
       context: ../../
       dockerfile: ./retention/docker/celery/Dockerfile
     image: &img worker
     container_name: celery
     # command: [celery, worker, --app=app1, --loglevel=INFO]


   beat:
     build:
       context: ../../
       dockerfile: ./retention/docker/celery/Dockerfile
     image: *img
     # command: [celery, beat, --app=app1, --loglevel=INFO]

How can I build just one image and reuse it?

I find it actually rebuild,,

eugene
– eugene

2019-11-25 14:15:50 +00:00
Commented Nov 25, 2019 at 14:15 — eugene
– eugene, Commented Nov 25, 2019 at 14:15

Adiii · Accepted Answer · 2019-11-25 17:22:49Z

4

You can re-use the same image in the same docker-compose but the order will mater, what if the image is not built yet and service B starting with that image that not exist yet which is supposed to be built in service A stage?

So add depends_on will help this race case also remove the build context from the beat service.

version: '3.7'
services:
  worker:
    image: worker_beat
    build:
      context: ../../
      dockerfile: ./retention/docker/celery/Dockerfile
    container_name: celery
    command: [celery, beat, --app=app1, --loglevel=INFO
  beat:
    image: worker_beat
    depends_on:
      - worker 
    command: [celery, beat, --app=app1, --loglevel=INFO]

to run your stack you will just need docker-compose up --build

edited Nov 25, 2019 at 17:22

answered Nov 25, 2019 at 14:53

Adiii

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1 Comment

tnwei Over a year ago

This right here should be accepted answer ^

LinPy · Accepted Answer · 2019-11-25 14:39:48Z

2

you need to use the same :

image: myimage:mytag

for the both services

then docker-compose build will use cache

answered Nov 25, 2019 at 14:39

LinPy

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