为什么我的 docker 容器不尊重我的权限？

Question

Dockerfile:

FROM ubuntu:latest

RUN apt install -y bash

CMD []

build and run:

docker build -t test .
docker run -it test bash

minimal reproduction:

root@8807902e27b4:/# mkdir parent
root@8807902e27b4:/# cd parent
root@8807902e27b4:/parent# mkdir example
root@8807902e27b4:/parent# chmod 000 example
root@8807902e27b4:/parent# ls -la
total 12
drwxr-xr-x 3 root root 4096 Apr 28 19:33 .
drwxr-xr-x 1 root root 4096 Apr 28 19:32 ..
d--------- 2 root root 4096 Apr 28 19:33 example
root@8807902e27b4:/parent# cd example
root@8807902e27b4:/parent/example# echo "test" > test.txt
root@8807902e27b4:/parent/example# chmod 100 test.txt
root@8807902e27b4:/parent/example# cat test.txt
test
root@8807902e27b4:/parent/example# ls -la
total 12
d--------- 2 root root 4096 Apr 28 19:33 .
drwxr-xr-x 3 root root 4096 Apr 28 19:33 ..
---x------ 1 root root    5 Apr 28 19:33 test.txt

In the above example, the cd example command should fail, and even if it doesn't, running cat test.txt should fail. Anyone know what's up?

Here are the same (working) commands run in osx:

beaushinkle@Beaus-MBP ~/p/example-docker> mkdir parent
beaushinkle@Beaus-MBP ~/p/example-docker> cd parent
beaushinkle@Beaus-MBP ~/p/e/parent> mkdir example
beaushinkle@Beaus-MBP ~/p/e/parent> chmod 000 example
beaushinkle@Beaus-MBP ~/p/e/parent> cd example
cd: Permission denied: 'example'
beaushinkle@Beaus-MBP ~/p/e/parent [1]> chmod 777 example
beaushinkle@Beaus-MBP ~/p/e/parent> cd example
beaushinkle@Beaus-MBP ~/p/e/p/example> echo "test" > test.txt
beaushinkle@Beaus-MBP ~/p/e/p/example> chmod 100 test.txt
beaushinkle@Beaus-MBP ~/p/e/p/example> cat test.txt
cat: test.txt: Permission denied

Answer 1

If the prompt is anything to go by, we are logged in as root in the minimal reproduction. Thus, we have root privileges and can read and write all files (external link) .