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

fixed by

docker image prune -f

looks like docker has a limit on maximum apt cache size on the host system

Answer 2

As @Danila and @Andriy pointed out this issue can easily be fixed running:

docker image prune -f
docker container prune -f

but posting this answer, as running just one of them didn't work for me (on MacOS X) - running both however does.

Answer 3

If you're using Docker Desktop, take care of the maximum disk image size you've specified in the settings. It can cause the issue if it gets full during the build.

Answer 4

I deleted lots of images then it fixed my problem.

Answer 5

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.

Answer 6

Apparently my root partition was full (maybe I've tried too many times to download packages through apt), and running sudo apt clean solved the issue