I setup the Google Compute Engine according the instructions and have the host(s) starting and provisioning correctly. However, none of my jobs get assigned to it.

Upon further investigation, I discovered that none of the labels were attached to the compute engine host. I double checked the labels field in the configuration and verified that the correct things are there, the labels seem to not propagate when the host is created.

I verified this by running the following in the script console on the master

import jenkins.model.Jenkins

Jenkins.instance.slaves.each { agent ->
    println agent.name + ' ' + agent.labelString
}

to which I found the result

gce-cloud-preemptable-bp86gx 
jenkins-slave-instance-group-pgb2 compute-engine docker linux
jenkins-slave-macstadium-207.254.40.72 macstadium ui-tests
jenkins-slave-macstadium-207.254.40.73 macstadium
Result: [com.google.jenkins.plugins.computeengine.ComputeEngineInstance[gce-cloud-preemptable-bp86gx], hudson.slaves.DumbSlave[jenkins-slave-instance-group-pgb2], hudson.slaves.DumbSlave[jenkins-slave-macstadium-207.254.40.72], hudson.slaves.DumbSlave[jenkins-slave-macstadium-207.254.40.73]]

The tag after 

gce-cloud-preemptable-jk54ko 

should be

compute-engine docker linux

but it is completely missing.