Need a way to see a message as it is routed through the Edge
An IoT Edge message correlation id should be provided so that specific message workflows can be diagnosed via module logging.
Check out the 1.0.10 release of IoT Edge. The runtime now produces metrics that can be used for debugging purposes. For example, queue size lets you track if messages are building up for certain modules. That seems like it is a first step towards your scenario. That said, I think we'll have to deliver the ability to do distributed tracing to completely fulfill your request.
While this is great for debugging/diagnose this is a must have for operations: log messages that are "lost" within IoT Edge - especially if they are deleted like by the IoT Hub Module and the Store And Forward TTL configuration. Refer to idea https://feedback.azure.com/forums/907045-azure-iot-edge/suggestions/37104274-log-a-warning-if-messages-are-deleted-from-the-sto
This is definitely a feature which is on our radar. Additional dev experience improvements we're considering are tools to help you debug modules and unit test modules.