Every dependency a service relies on is another way for it to fail, so reliability engineering means questioning which dependencies are truly necessary and designing graceful degradation for the rest. Edge systems like load balancers and API gateways tend to be dependency-light because they carry outsized responsibility for platform availability. Envoy Proxy is offered as an example: it fetches xDS configuration periodically and caches it in memory, so request processing continues even if the xDS service goes down. Observability (logging, tracing) should be treated as best-effort rather than a hard dependency, using async logging and buffering so customer traffic isn't blocked by observability outages.
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Why Dependencies MatterWhy Edge Systems Tend to Be Dependency-LightEliminating Dependencies Isn’t Always NecessaryGet Benjamin Cane ’s stories in your inboxA Real-World ExampleDon’t Make Observability a Hard DependencyFinal ThoughtsQuestions this post answers
How does Envoy Proxy stay available if the xDS control plane goes down?
Envoy continues routing traffic using its last known configuration. It fetches configuration from the xDS service periodically and stores it in memory, so request processing relies on that cached local state rather than calling xDS for every request. This means an xDS outage does not stop traffic from being routed, even though Envoy still depends on xDS for updates. Anyone designing resilient proxy or gateway systems can track patterns like this on daily.dev.
Should logging and tracing be treated as hard dependencies in a production service?
No, observability should be best effort rather than a hard requirement for serving traffic. If a logging or tracing backend becomes unavailable, customer traffic should keep flowing rather than stopping. This is achieved through asynchronous logging, buffering, and truncation policies so operational visibility issues never block customer-facing availability. Engineers weighing observability tradeoffs against uptime can follow this reasoning on daily.dev.