I am having the same issue and spend a long time tracing it down what seems to be AppArmor.
Different images I tried:
Ubuntu
$ docker run -it ubuntu /bin/bash
bash: /root/.bashrc: Permission denied
root@60bb6a5cca3f:/#
Journal:
May 21 19:44:37 Yoga-C940 audit[7988]: AVC apparmor="DENIED" operation="open" profile="snap.docker.dockerd" name="/root/.bashrc" pid=7988 comm="bash" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
May 21 19:44:37 Yoga-C940 kernel: audit: type=1400 audit(1590083077.908:171): apparmor="DENIED" operation="open" profile="snap.docker.dockerd" name="/root/.bashrc" pid=7988 comm="bash" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
nginx
$ docker run -it nginx
2020/05/21 17:42:36 [emerg] 1#1: open() "/etc/nginx/nginx.conf" failed (13: Permission denied)
nginx: [emerg] open() "/etc/nginx/nginx.conf" failed (13: Permission denied)
Journal:
May 21 19:43:20 Yoga-C940 audit[7860]: AVC apparmor="DENIED" operation="open" profile="snap.docker.dockerd" name="/etc/nginx/nginx.conf" pid=7860 comm="nginx" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
May 21 19:43:20 Yoga-C940 kernel: audit: type=1400 audit(1590083000.646:170): apparmor="DENIED" operation="open" profile="snap.docker.dockerd" name="/etc/nginx/nginx.conf" pid=7860 comm="nginx" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
Apache / httpd
docker run -it httpd
/bin/sh: 0: Can't open /usr/local/bin/httpd-foreground
Journal:
May 21 19:46:09 Yoga-C940 audit[8143]: AVC apparmor="DENIED" operation="open" profile="snap.docker.dockerd" name="/usr/local/bin/httpd-foreground" pid=8143 comm="httpd-foregroun" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
May 21 19:46:09 Yoga-C940 kernel: audit: type=1400 audit(1590083169.799:172): apparmor="DENIED" operation="open" profile="snap.docker.dockerd" name="/usr/local/bin/httpd-foreground" pid=8143 comm="httpd-foregroun" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
Using --cap-add=SYS_PTRACE and --security-opt=apparmor:unconfined as mentioned here, doesn’t seem to fix anything.
Snap version:
snap 2.44.3+20.04
snapd 2.44.3+20.04
series 16
ubuntu 20.04
kernel 5.4.0-31-generic
Docker version:
Client:
Version: 18.09.9
API version: 1.39
Go version: go1.13.4
Git commit: 1752eb3
Built: Sat Nov 16 01:05:26 2019
OS/Arch: linux/amd64
Experimental: false
Server:
Engine:
Version: 18.09.9
API version: 1.39 (minimum version 1.12)
Go version: go1.13.4
Git commit: 9552f2b
Built: Sat Nov 16 01:07:48 2019
OS/Arch: linux/amd64
Experimental: false
Can confirm that booting up in kernel 5.4.0-29-generic does not cause the above issue.