[ubuntu 20.04] update문제 해결

apt update오류 

오류 문구

Err:5 https://packages.cloud.google.com/apt kubernetes-xenial InRelease                                                 
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY B53DC80D13EDEF05
Hit:12 http://ppa.launchpad.net/team-xbmc/ppa/ubuntu focal InRelease                                                    
Fetched 222 kB in 2s (92.9 kB/s)                                                       
Reading package lists... Done
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://packages.cloud.google.com/apt kubernetes-xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY B53DC80D13EDEF05
W: Failed to fetch https://apt.kubernetes.io/dists/kubernetes-xenial/InRelease  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY B53DC80D13EDEF05
W: Some index files failed to download. They have been ignored, or old ones used instead.

현상

kubernetes 관련 업데이트 족에서 오류가 발생함.

아래 처럼 key를 등록해도 안됨.. 

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv B53DC80D13EDEF05

해결

#sudo curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | gpg --dearmor | sudo dd status=none of=/usr/share/keyrings/kubernetes-archive-keyring.gpg

#sudo echo "deb [signed-by=/usr/share/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list

#sudo apt update

출처 

https://github.com/kubernetes/release/issues/1982

Expired key - "Google Cloud Packages Automatic Signing Key" · Issue #1982 · kubernetes/release