Docker: Copy files from another image

COPY --from is used for mulit-stage builds and it is used to copy from another image, either by referencing a local image name or a tag available on a Docker registry.

COPY --from=nginx:latest /etc/nginx/nginx.conf /nginx.conf

It can also be used for copying from stages created earlier in the Dockerfile:

# stage 1
FROM alpine as git
RUN apk add git

# stage 2
FROM git as fetch
RUN git clone .

# stage 3
FROM nginx as site
COPY --from=fetch /repo/docs/ /usr/share/nginx/html