[SOLVED] Dockerfile cannot run apt-get (exit code: 100)

Dockerfile cannot run apt-get (exit code: 100)

I'm working with yocto and I'm trying to build my custom image using this a base: yocto-ubuntu-20.04.

I have this simple docker file:

FROM reliableembeddedsystems/yocto:ubuntu-20.04-base
RUN apt-get update

But I'm getting permissions error when building:

user@user$ sudo docker build .
[...]
------                                                                                                               
 > [2/2] RUN apt-get update:
0.214 Reading package lists...
0.753 E: Could not open lock file /var/lib/apt/lists/lock - open (13: Permission denied)
0.753 E: Unable to lock directory /var/lib/apt/lists/
------
Dockerfile:2
--------------------
   1 |     FROM reliableembeddedsystems/yocto:ubuntu-20.04-base
   2 | >>> RUN apt-get update
   3 |     
--------------------
ERROR: failed to solve: process "/bin/sh -c apt-get update" did not complete successfully: exit code: 100

If I add sudo to RUN apt-get update line I get a different error asking for password:

 > [2/2] RUN sudo apt-get update:                                                                                    
0.207 sudo: a terminal is required to read the password; either use the -S option to read from standard input or configure an askpass helper
------
Dockerfile:2
--------------------
   1 |     FROM reliableembeddedsystems/yocto:ubuntu-20.04-base
   2 | >>> RUN sudo apt-get update
   3 |     
--------------------
ERROR: failed to solve: process "/bin/sh -c sudo apt-get update" did not complete successfully: exit code: 1

Which is the correct way to work with it?

Another question: if run a container using the base image, I notice that I can use sudo. But, how am I supposed to know the password? Is it okay to use sudo in here?

Solution

It seems that the base image sets a user other than root. This can be fixed using:

FROM reliableembeddedsystems/yocto:ubuntu-20.04-base
USER root
RUN apt-get update