/dev/mem no such file or directory in Ubuntu Linux 14.04 container

General
6

I know this is several months old, but I had the same issue myself and was able to solve it without using “–privileged”. Might help someone else.

TL;DR: add the /dev/mem device and add the sys_rawio capability.

Long version (focused on security):

#dockerfile
FROM alpine@sha256:3d44fa76c2c83ed9296e4508b436ff583397cac0f4bad85c2b4ecc193ddb5106

    RUN apk --no-cache add \
            dmidecode 

# ...other configuration

#docker-compose
dmidecode:
 build: 
   #...build context, etc
 network_mode: "none"         # optional, more secure
 devices:                     # required
   - "/dev/mem:/dev/mem"
 cap_drop:                    # optional, more secure
   - ALL
 cap_add:                     # required
   - sys_rawio
 read_only: true              # optional, more secure

Because I can really only see dmidecode being used to spit out system information, I removed network access entirely.

I don’t know that much about dmidecode, but it’s possible you might need to mount other devices depending on what you’re doing. Maybe even capabilities. But I think it’s clear that with some trial and error, you can avoid using --privileged.

1 Like