Elimine la estrella de COPY, con este Dockerfile:
FROM ubuntu
COPY files/ /files/
RUN ls -la /files/*
La estructura está ahí:
$ docker build .
Sending build context to Docker daemon 5.632 kB
Sending build context to Docker daemon
Step 0 : FROM ubuntu
---> d0955f21bf24
Step 1 : COPY files/ /files/
---> 5cc4ae8708a6
Removing intermediate container c6f7f7ec8ccf
Step 2 : RUN ls -la /files/*
---> Running in 08ab9a1e042f
/files/folder1:
total 8
drwxr-xr-x 2 root root 4096 May 13 16:04 .
drwxr-xr-x 4 root root 4096 May 13 16:05 ..
-rw-r--r-- 1 root root 0 May 13 16:04 file1
-rw-r--r-- 1 root root 0 May 13 16:04 file2
/files/folder2:
total 8
drwxr-xr-x 2 root root 4096 May 13 16:04 .
drwxr-xr-x 4 root root 4096 May 13 16:05 ..
-rw-r--r-- 1 root root 0 May 13 16:04 file1
-rw-r--r-- 1 root root 0 May 13 16:04 file2
---> 03ff0a5d0e4b
Removing intermediate container 08ab9a1e042f
Successfully built 03ff0a5d0e4b