Copy multiple directories with one command

Question

Is there any way to copy multiple directories in one command, to reduce the number of layers? E.g., instead of:

COPY dirone ./dirone
COPY dirtwo ./dirtwo
COPY dirthree ./dirthree

I want to do:

COPY dirone/ dirtwo/ dirthree/ ./

However, this copies the contents of the directories... but I want to copy the directories themselves.

Answer 1

As BMitch answered, that is expected COPY behaviour.

An alternative would be to ADD the contents of a tarball.

Create the initial tarball

tar -cvf dirs.tar dirone/ dirtwo/ dirthree/

Add it to the build

FROM busybox
ADD dirs.tar /
CMD find /dirone /dirtwo /dirthree

The tarball is automatically extracted

? ?docker run c28f96eadd58
/dirone
/dirone/one
/dirtwo
/dirtwo/two
/dirthree
/dirthree/three

Note that every time you update the tar file you are invalidating the Docker build cache for that step. If you are dealing with a lot of files you might want to be smart about when you do the tar -c. You could also use tar -u if you can deal with files not being automatically deleted from the tarball.

[ -f dirs.tar ] && tar -uf dirs.tar something || tar -cf dirs.tar something

Answer 2

1. You can copy entire parent directory and exclude all other folders/files in .dockerignore file

Dockerfile

COPY . ./

.dockerignore

/dirfour
/dirfive
/file.txt

2. Or you can ignore entire parent folder in .dockerignore and include only folders you want to copy

Dockerfile

COPY . ./

.dockerignore

/**
!/dirone
!/dirtwo
!/dirthree

Answer 3

Along the lines of the previous answers, but with the (relatively modern) multiple FROM support:

FROM alpine AS src
RUN mkdir -p /src /dst/a /dst/b /dst/rest
WORKDIR /src
COPY . .
RUN true \
    && mv a aa aaa /dst/a/ \
    && mv b bb bbb /dst/b/ \
    && mv * /dst/rest/


FROM realbaseimage

COPY --stage=src /dst/a .
RUN do stuff that needs only a

COPY --stage=src /dst/b .
RUN do stuff that needs only b

COPY --stage=src /dst/rest .
RUN do stuff that needs the rest

This will layer and cache properly: the layers created in the src stage won't be pushed, so the copy/run layers in the final image will be sized and cached according to the contents of parts rather than having duplication and cache invalidation of the whole when changing one thing.

You can change the src stage's base image to whatever, but it needs to have the mv binary, obviously.