docker安裝之【異常】NO_PUBKEY

W: GPG error: https://apt.dockerproject.org ubuntu-trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY F76221572C52609D

問題:執行 apt-get update 時錯誤

W: GPG 錯誤：https://apt.dockerproject.org ubuntu-trusty InRelease: 因爲沒有公鑰，沒法驗證下列簽名： NO_PUBKEY F76221572C52609D

解決：

# apt-key adv --keyserver keyserver.ubuntu.com --recv-keys F76221572C52609D

Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --homedir /tmp/tmp.O9IakFlDl6 --no-auto-check-trustdb --trust-model always --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --keyring /etc/apt/trusted.gpg.d/apt.postgresql.org.gpg --keyserver keyserver.ubuntu.com --recv-keys 16126D3A3E5C1192
gpg: 下載密鑰‘3E5C1192’，從 hkp 服務器 keyserver.ubuntu.com
gpg: 密鑰 3E5C1192：公鑰「Ubuntu Extras Archive Automatic Signing Key <ftpmaster@ubuntu.com>」已導入
gpg: 合計被處理的數量：1
gpg: 已導入：1

#apt-get clean

#apt-get update