เริ่มจาก sudo apt update
จะพบว่า key มัน expire นะ
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://cf-cli-debian-repo.s3.amazonaws.com stable InRelease: The following signatures were invalid: EXPKEYSIG 172B5989FCD21EF8 CF CLI Team cf-cli-eng@pivotal.io
W: Failed to fetch https://packages.cloudfoundry.org/debian/dists/stable/InRelease The following signatures were invalid: EXPKEYSIG 172B5989FCD21EF8 CF CLI Team cf-cli-eng@pivotal.io
W: Some index files failed to download. They have been ignored, or old ones used instead.
พอลอง google ก็จะมีกระทู้ https://github.com/cloudfoundry/cli/issues/2046
นั้นคือให้ add key ใหม่ด้วยคำสั่ง
wget -q -O - https://packages.cloudfoundry.org/debian/cli.cloudfoundry.org.key | sudo apt-key add -