We are seeing this in our CI builds with Kitchen and EC2
$ sudo apt-get -q install percona-server-client-5.6=5.6.44-86.0-1.xenial
Reading package lists…
Building dependency tree…
Reading state information…
The following additional packages will be installed:
libdbi-perl libperconaserverclient18.1 percona-server-common-5.6
Suggested packages:
libclone-perl libmldbm-perl libnet-daemon-perl libsql-statement-perl
The following NEW packages will be installed:
libdbi-perl libperconaserverclient18.1 percona-server-client-5.6 percona-server-common-5.6
0 upgraded, 4 newly installed, 0 to remove and 22 not upgraded.
Need to get 2,691 kB of archives.
After this operation, 43.9 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
WARNING: The following packages cannot be authenticated!
percona-server-common-5.6 libperconaserverclient18.1 percona-server-client-5.6
because…
$ sudo apt-get update
Hit:1 [url]http://us-west-2.ec2.archive.ubuntu.com/ubuntu[/url] xenial InRelease
Hit:2 [url]http://us-west-2.ec2.archive.ubuntu.com/ubuntu[/url] xenial-updates InRelease
Hit:3 [url]http://us-west-2.ec2.archive.ubuntu.com/ubuntu[/url] xenial-backports InRelease
Get:4 [url]http://repo.percona.com/apt[/url] xenial InRelease [15.9 kB]
Hit:5 [url]http://security.ubuntu.com/ubuntu[/url] xenial-security InRelease
Ign:4 [url]http://repo.percona.com/apt[/url] xenial InRelease
Fetched 15.9 kB in 0s (41.0 kB/s)
Reading package lists… Done
W: GPG error: [url]http://repo.percona.com/apt[/url] xenial InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 9334A25F8507EFA5
W: The repository ‘Percona Repo xenial InRelease’ is not signed.
N: Data from such a repository can’t be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
The key seems to have been installed as usual and nothing changed in our pipeline config.