| cloud.google.com/go/pubsub | Package pubsub provides an easy way to publish and receive Google Cloud Pub/Sub messages, hiding the details of the underlying server RPCs. |
| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| flag | Package flag implements command-line flag parsing. |
| github.com/golang/glog | Package glog implements logging analogous to the Google-internal C++ INFO/ERROR/V setup. |
| github.com/golang/protobuf/proto | Package proto provides functionality for handling protocol buffer messages. |
| github.com/google/trillian/skylog/storage/gcp/gcppb | |
| golang.org/x/time/rate | Package rate provides a rate limiter. |