Currently our puppet compilers compiler02.puppet3-diffs.eqiad.wmflabs and compiler03.puppet3-diffs.eqiad.wmflabs are Jessie hosts. Until somewhat recently upgrading was blocked by dependency on an etcd package for Stretch. Now that this is available let's plan to upgrade them.
This also is a good time to update the cloud/labs project name (probably by creating a new project) to something like "puppet-diffs" since the current name "puppet3-diffs" has become outdated.