title: Permission denied as root in docker containers
body: <p>In the last couple of days I'm having some issues at building or running docker containers.</p>
  
  <p>It seems that root doesn't have permission of having access to the filesystem.</p>
  
  <p>Eg. I've created this very simple Dockerfile</p>
  
  <pre><code>FROM centos
  
  RUN id &amp;&amp; ls -l /usr/bin/yum /usr/bin/dnf-3 &amp;&amp; yum install mlocate
  </code></pre>
  
  <p>and when I try to build the image I get the error</p>
  
  <pre><code>Step 1/2 : FROM centos
   ---&gt; 470671670cac
  Step 2/2 : RUN id &amp;&amp; ls -l /usr/bin/yum /usr/bin/dnf-3 &amp;&amp; yum install mlocate
   ---&gt; 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 -&gt; dnf-3
  /usr/libexec/platform-python: can't open file '/usr/bin/yum': [Errno 13] Permission denied
  The command '/bin/sh -c id &amp;&amp; ls -l /usr/bin/yum /usr/bin/dnf-3 &amp;&amp; yum install mlocate' returned a non-zero code: 2
  </code></pre>
  
  <p>The issue seems to be more generic as even with ubuntu or alpine I get similar errors, so I suspect is related to Ubuntu.</p>
  
  <p>Consider that before I could perform any task without problems.</p>
  
  <p>I've tried adding capabilities and stopping apparmor but it doesn't have any effect. </p>
  
  <p><strong>Docker info</strong></p>
  
  <pre><code>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: &lt;unknown&gt;
    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
  </code></pre>