in 04-packer.md, error while installing mongodb

[sumitchinchansure]

@Artemmkin I am new to IaaC and I am following your tutorial,
Getting this error while installing mongodb :

==> googlecompute: W: GPG error: http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.2 Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY D68FA50FEA312927
==> googlecompute: W: The repository 'http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.2 Release' is not signed.

Could you please guide me please ?

[bpeter340]

https://askubuntu.com/questions/842592/apt-get-fails-on-16-04-or-18-04-installing-mongodb