CentOS 6.7のvagrantイメージで出るエラー

Downloading Packages:
warning: rpmts_HdrFromFdno: Header V4 RSA/SHA1 Signature, key ID ef8d349f: NOKEY
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-puppetlabs-PC1

The GPG keys listed for the "Puppet Labs PC1 Repository el 6 - x86_64" repository are already installed but they are not correct for this package.
Check that the correct key URLs are configured for this repository.

PuppetのGPG KEYのライセンス切れらしい

というわけで、下記の場所からひとまず新しいGPG KEYを取得して使用できるようにする

wget http://yum.puppetlabs.com/RPM-GPG-KEY-puppetlabs
wget https://yum.puppetlabs.com/RPM-GPG-KEY-puppet
rpm --import RPM-GPG-KEY-puppet
rpm --import RPM-GPG-KEY-puppetlabs

おそらくこれで使えるようになるはず。