Repository is not signed in docker build

Question

I have the following Dockerfile that uses the latest Ubuntu image pulled from dockerhub:

FROM ubuntu:latest  
RUN apt-get update  && apt-get install -y           


        

Answer 1

I had this problem on one of my two machines. Doing a ls -ld /tmp I got

drwxrwxrwt 3 root root 4096 May 15 20:46 /tmp

for the working one and

drwxr-xr-t 1 root root 4096 May 26 05:44 /tmp

for the failing one. After I did chmod 1777 /tmp, it worked!!

EDIT:

So, I dived a little deeper into this problem and realized there was something fundamentally wrong. I put my problems in another question and later found the answer that solved this myself: https://stackoverflow.com/a/62088961/7387935

The key point here is that on the machine that was working correctly I had aufs as storage driver and on the faulty one it was overlay2. After I changed that, all peissions were correct.