Permission denied as root in docker containers

问题

In the last couple of days I'm having some issues at building or running docker containers.

It seems that root doesn't have permission of having access to the filesystem.

Eg. I've created this very simple Dockerfile

FROM centos

RUN id && ls -l /usr/bin/yum /usr/bin/dnf-3 && yum install mlocate

and when I try to build the image I get the error

Step 1/2 : FROM centos
 ---> 470671670cac
Step 2/2 : RUN id && ls -l /usr/bin/yum /usr/bin/dnf-3 && yum install mlocate
 ---> Running in f7b32a009a74
uid=0(root) gid=0(root) groups=0(root)
-rwxr-xr-x 1 root root 1954 Dec 19 15:43 /usr/bin/dnf-3
lrwxrwxrwx 1 root root    5 Dec 19 15:43 /usr/bin/yum -> dnf-3
/usr/libexec/platform-python: can't open file '/usr/bin/yum': [Errno 13] Permission denied
The command '/bin/sh -c id && ls -l /usr/bin/yum /usr/bin/dnf-3 && yum install mlocate' returned a non-zero code: 2

The issue seems to be more generic as even with ubuntu or alpine I get similar errors, so I suspect is related to Ubuntu.

Consider that before I could perform any task without problems.

I've tried adding capabilities and stopping apparmor but it doesn't have any effect.

Docker info

Client:
 Debug Mode: false

Server:
 Containers: 18
  Running: 0
  Paused: 0
  Stopped: 18
 Images: 20
 Server Version: 19.03.8
 Storage Driver: overlay2
  Backing Filesystem: <unknown>
  Supports d_type: true
  Native Overlay Diff: true
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 7ad184331fa3e55e52b890ea95e65ba581ae3429
 runc version: 
 init version: fec3683
 Security Options:
  apparmor
  seccomp
   Profile: default
 Kernel Version: 5.4.0-31-generic
 Operating System: Ubuntu Core 16
 OSType: linux
 Architecture: x86_64
 CPUs: 8
 Total Memory: 7.475GiB
 Name: gurdulu-xps
 ID: E5JA:3WKI:JWFQ:M5J2:CAZ7:VVKI:2ADB:3W7W:F3F4:VYXZ:7JLP:R7C4
 Docker Root Dir: /var/snap/docker/common/var-lib-docker
 Debug Mode: false
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false

WARNING: No swap limit support

回答1:

It was apparmor in combination with snap. The profile coming with the snap installation had in some way become invalid in the last couple of days.

To be honest I didn't investigate and tried removing the snap and installing with apt.

Now it works fine.

来源：https://stackoverflow.com/questions/61982114/permission-denied-as-root-in-docker-containers

标签

Docker

ubuntu-20.04