Question 301786 in Docker Question posted in
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Two Dockerfiles share resources built by common build container

I have a Dockerfile that builds some webpack stuff:

FROM node:21 as assets
COPY ...
RUN npm install
RUN npm run build

That produces a dist directory with roughly the following content:

webpack-stats.json
bundle.js
bundle.css

Now i have two Containers that need the result:

FROM python:latest
COPY --from=assets /app/dist/webpack-stats.json .
CMD python ...

FROM nginx:latest
COPY --from=assets /app/dist/ .
CMD nginx ...

However, those can’t be put in the same Dockerfile, since one Dockerfile only builds one image / container.
I also want to avoid running the build container twice to avoid inconsistency and long build times.

Is there a way to built only once, but use it in two containers?

Tags:

2

Answers


  1. 0

    Is there a way to built only once, but use it in two containers?

    So tag it.

    /assets/Dockefile
    FROM node:21 as assets
    COPY ...
    RUN npm install
    RUN npm run build
/app1/Dockerfile
    FROM assets AS assets
    FROM python:latest
    COPY --from=assets /app/dist/webpack-stats.json .
    CMD python ...

    And then build with

    cd assets
docker build -t assets .
cd ..
cd app1
docker build .

    "Professionally" you would publish assets from a separate CI/CD into a private docker repository, like for example to gitlab project container registry, and use the full name in depende dockerfile.

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  2. 0

    This is why people have Docker Hub accounts. I didn’t try this, just rolled off the fingers.

    In one directory you have Dockerfile containing

    FROM node:21 as assets
COPY ...
RUN npm install
RUN npm run build

    Now

    docker login
docker build --pull -t <yourdockerusername>/mybasebuild .
docker push <yourdockerusername>/mybasebuild

    Now in a different directory you have a Dockerfile containing this

    FROM mybasebuild as Builder
FROM python:latest
COPY --from=Builder /app/dist/webpack-stats.json .
CMD python ...

    in case you logged out

    docker login
docker build --pull -t <yourdockerusername>/mylittlepython .
docker push <yourdockerusername>/mylittlepython

    In a third directory you have a Dockerfile containing this

    FROM mybasebuild as Builder
FROM nginx:latest
COPY --from=assets /app/dist/ .
CMD nginx ...

    If you logged out of docker log back in and

    docker build --pull -t <yourdockerusername>/mylittleinx .
docker push <yourdockerusername>/mylittleinx
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