Time Series Bridge exports a Stackdriver metric oldest_metric_age that can be used to detect configured metrics that no longer get updated.

policy.yaml file in this directory contains a sample Stackdriver alerting policy called "Time Series Bridge Stalled". It will trigger if at least one of the metrics have not had any data imported for 30 minutes.

The policy also has a metric absense condition that will trigger if the oldest_metric_age metric itself has not been updated for 30 minutes. This can be used to detect issues with Time Series Bridge itself.

You can push this sample policy to your Stackdriver project by running:

gcloud alpha monitoring policies create --policy-from-file=policy.yaml

Note, that the policy does not actually have any notifications enabled, so you will need to adjust it manually (or create another YAML file based on policy.yaml) if you'd like to be notified when it triggers.