Build docker image that depends on a local "Dockerfile"

Question

I have the following folder structure:

my_package
|- docker_compose.yml
|- a
   |- Dockerfile
|- b
   |- Dockerfile

Here, my docker-compose.yml is:

version: '2'
services:
  a:
    build: 
      context: a
      dockerfile: Dockerfile
  b:
    build: 
      context: b 
      dockerfile: Dockerfile

When I run docker-compose build I expect two output images, one for a and one for b.

Here's a/Dockerfile

FROM ubuntu
RUN touch AAA

Here's b/Dockerfile

FROM <a> # NOT SURE WHAT TO PUT HERE
RUN touch BBB

I would like the b image to contain two files in the rootdir, AAA and BBB, which requires one Dockerfile to depend on another.

Is this possible? Is there any workaround to make two Docker images (with a dependency between them) build in one docker-compose build command?

I'm stuck with Docker version 1.12.6, build 78d1802 (which is compatible with version 2 syntax only).

score 9 · Accepted Answer · edited Feb 19 '18 at 22:58

9

You can use depends_on in your docker-compose.yml, I know it is available in docker-compose YAML version 3, to express that service B depends on A and docker-compose will follow the dependency chain you express and build A first. See an explanation of depends_on here.

Since B is FROM A as your Dockerfile for B expresses both files AAA and BBB will be available in service B as long as the permissions for file AAA and file BBB are the same and in the this case you are running as root in both service A and service B when you execute the touch command.

version: '3'
services:
  a:
    build: 
      context: a
      image: a
      dockerfile: Dockerfile
  b:
    build: 
      context: b 
      image: b
      dockerfile: Dockerfile
    depends_on: 
    - a

Edit (by OP):

You can use depends_on in v2 too, but using an array.
Make sure to add the image in the docker-compose.yml to specify the generated image, so that b can be generated FROM a

edited Feb 19 '18 at 22:58

Jedi

3,088
2
28
47

answered Feb 19 '18 at 22:01

Brian Ogden

18,439
10
97
176

Thanks. Unfortunately, I cannot install a newer Docker engine. I'm stuck at `1.12.6` and hence `v2` docker-compose. Also, I'm not sure how to add the dependency in `b`'s Dockerfile – Jedi Feb 19 '18 at 22:22
@Jedi, depends_on might be available for version 2 I do not know for sure. Also being stuck a a version is often times a sign of larger architectural system design issues, that need to be addressed – Brian Ogden Feb 19 '18 at 22:25
No argument there (about deeper issues). It's someone else's borrowed environment. Anyways, `depends_on` does exist for v2, with some syntactic differences (needs an array); however, I'm not sure how to make one Dockerfile depend on another (what does the FROM in `b/Dockerfile` need to be) – Jedi Feb 19 '18 at 22:32
@Jedi the FROM in b/Dockerfile would be the image name of a service. you can set the image name in your docker-compose.yml for both A and B services – Brian Ogden Feb 19 '18 at 22:39

Build docker image that depends on a local "Dockerfile"

1 Answers1