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 g++ llvm lcov
when I launch the docker build command, the following errors occur:
Err:2 http://archive.ubuntu.com/ubuntu bionic InRelease
At least one invalid signature was encountered.
Err:1 http://security.ubuntu.com/ubuntu bionic-security InRelease
At least one invalid signature was encountered.
Err:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease
At least one invalid signature was encountered.
Err:4 http://archive.ubuntu.com/ubuntu bionic-backports InRelease
At least one invalid signature was encountered.
Reading package lists...
W: GPG error: http://archive.ubuntu.com/ubuntu bionic InRelease: At least one invalid signature was encountered.
E: The repository 'http://archive.ubuntu.com/ubuntu bionic InRelease' is not signed.
W: GPG error: http://security.ubuntu.com/ubuntu bionic-security InRelease: At least one invalid signature was encountered.
E: The repository 'http://security.ubuntu.com/ubuntu bionic-security InRelease' is not signed.
W: GPG error: http://archive.ubuntu.com/ubuntu bionic-updates InRelease: At least one invalid signature was encountered.
E: The repository 'http://archive.ubuntu.com/ubuntu bionic-updates InRelease' is not signed.
W: GPG error: http://archive.ubuntu.com/ubuntu bionic-backports InRelease: At least one invalid signature was encountered.
E: The repository 'http://archive.ubuntu.com/ubuntu bionic-backports InRelease' is not signed.
I read here https://superuser.com/questions/1331936/how-can-i-get-past-a-repository-is-not-signed-message-when-attempting-to-upgr that you can pass this error using --allow-unauthenitcated or --allow-insecure-repositories but both seem to me workarounds that may compromize security of the container.
EDIT
Tried to pull ubuntu:18.04, ubuntu:19:04, ubuntu:19.10 same error with different distro name
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
In addition, the following commands should help clean up space:
docker system df # which can show disk usage and size of 'Build Cache'
docker image prune # add -f or --force to not prompt for confirmation
docker container prune # add -f or --force to not prompt for confirmation