EnvoyCon North America 2022

Monitoring and debugging modern cloud-based applications is challenging due to their highly distributed nature. End-to-end distributed tracing (tracing individual calls through a request's lifecycle) has emerged to be essential in a developer's toolbox as they're critical to describing a request's flow through a microservice. Unfortunately, to enable distributed tracing, each service along the request tree needs to propagate a global request ID to help link the related requests (i.e., link incoming requests with spawned backend requests). Enabling such header propagation can be non-trivial for large microservices with 100+ independent services or for legacy apps where instrumentation is hard. This talk explores whether distributed tracing can be made more accessible by eliminating the need for application instrumentation. We describe a method that combines observations external to the app (using an envoy-based service mesh) with timing analysis of the requests to construct end-to-end traces. In an evaluation with a simple microservice, this preliminary method boosts trace reconstruction accuracy to 96% (compared to 77% for a baseline), and can help answer useful developer queries.